We propose the surface of topological superconductors as a platform for realizing two-dimensional flat bands, where electron interactions play a crucial role. The surface flat bands originate from topological features supported by two key mechanisms: (1) a trivial Chern number prevents the zero-energy states from merging into the continuum of the bulk spectrum, thereby ensuring their confinement within the superconducting gap; and (2) weak spin conservation allows the gap function to exhibit phase winding. As a consequence, the surface exhibits a remarkably high density of states at nearly zero energy. Such surface states are likely to be realized in the candidate topological superconductor UTe$_2$. Our results provide important insights into the interpretation of recent Josephson STM experiments on UTe$_2$.

Magneto-optic Kerr effect (MOKE) is a powerful probe of broken time-reversal symmetry ($\mathcal{T}$), typically used to study ferromagnets. While MOKE has been observed in some antiferromagnets (AFMs) with vanishing magnetization, it is often associated with structures whose symmetry is lower than basic collinear, bipartite order. In contrast, theory predicts a mechanism for MOKE intrinsic to all AFMs of A-type, i.e. layered AFMs in which ferromagnetic layers are antiferromagnetically aligned. Here we report the first experimental confirmation of this mechanism. We achieve this by measuring the imaginary component of MOKE as a function of photon energy in MnBi$_2$Te$_4$, an A-type AFM where $\mathcal{T}$ is preserved in combination with a translation. By comparing the experimental results with model calculations, we demonstrate that observable MOKE should be expected in all collinear A-type AFMs with out-of-plane spin order, thus enabling optical detection of AFM domains and expanding the scope of MOKE to few-layer AFMs.

We propose a way to generate a one-dimensional topological superconductor from a monolayer of a transition metal dichalcogenide coupled to a Bernal-stacked bilayer of graphene under a displacement field. With proper gating, this structure may be tuned to form three parallel pads of superconductors creating two planar Josephson junctions in series, in which normal regions separate the superconductors. Two characteristics of the system which are essential for our discussion are spin orbit coupling induced by the transition metal dichalcogenides and the variation of the Fermi velocities along the Fermi surface. We demonstrate that these two characteristics lead to one-dimensional topological superconductivity occupying large parts in the parameter space defined by the two phase differences across the two junctions and the relative angle between the junctions and the lattice. An angle-shaped device in which this angle varies in space, combined with proper phase tuning, can lead to the formation of domain walls between topological and trivial phases, supporting a zero-energy Majorana mode, within the bulk of carefully designed devices. We derive the spectrum of the Andreev bound states and show that Ising spin-orbit coupling leaves the topological superconductor gapless, and the Rashba spin-orbit coupling opens a gap in its spectrum. Our analysis shows that the transition to a gapped topological state is a result of the band inversion of Andreev states.

While moir\'e phenomena have been extensively studied in low-carrier-density systems such as graphene and semiconductors, their implications for metallic systems with large Fermi surfaces remain largely unexplored. Using GPU-accelerated large-scale ab-initio quantum transport simulations, we investigate spin transport in two distinct platforms: twisted bilayer MoTe$_2$ (semiconductor, from lightly to heavily doping) and NbX$_2$ ($X$ = S, Se; metals). In twisted MoTe$_2$, the spin Hall conductivity (SHC) evolves from $4\tfrac{e}{4\pi}$ at $5.09^\circ$ to $10\tfrac{e}{4\pi}$ at $1.89^\circ$, driven by the emergence of multiple isolated Chern bands. Remarkably, in heavily doped metallic regimes--without isolated Chern bands--we observe a universal amplification of the spin Hall effect from Fermi surface reconstruction under long-wavelength potential, with the peak SHC tripling from $6\tfrac{e}{4\pi}$ at $5.09^\circ$ to $17\tfrac{e}{4\pi}$ at $3.89^\circ$. For prototypical moir\'e metals like twisted NbX$_2$, we identify a record SHC of $-17\tfrac{e}{4\pi}$ (-5200 $(\hbar / e)S/cm$ in 3D units), surpassing all known bulk materials. These results establish moir\'e engineering as a powerful strategy for enhancing spin-dependent transport, and advancing ab-initio methodologies to bridge atomic-scale precision with device-scale predictions in transport simulations.

Transition metal penta-tellurides, ZrTe5 and HfTe5 have been recently drawn a lot of attention due to their fascinating physical properties and for being prominent materials showing topological phase transitions. In this study, we investigated mechanical, thermophysical and optoelectronic properties of these materials which remained almost unexplored till now. We also studied electronic properties and compared those with previous studies. We used Density Functional Theory (DFT) based calculations to study all of these properties. This study suggests that the materials are mechanically stable, possess high mechanical and bonding anisotropy and are brittle in nature. Our study also suggests that the compounds are soft in nature and they contain a mixture of covalent and metallic bonding. Investigation of thermophysical properties, namely, Gr\"uneisen parameter and Debye temperature indicates weak bonding strength in these compounds. Analysis of melting temperature, thermal expansion coefficient, heat capacity, radiation factor, acoustic impedance, and minimum thermal conductivity suggests their possible application in acoustic and thermoelectric devices. Examination of their optical characteristics reveals that they have a considerable reflectivity from the infrared to the ultraviolet region. The refractive indices of these materials are high at low energy so they are potential candidates for reflective coating of solar radiation. There have been debates over exact topological natures of these compounds, whether they are semi-metals or insulators. Our study of electronic band structure and density of states reveal that spin-orbit interaction is responsible for enhancing energy gaps and promoting insulating characteristics in these compounds.

We investigate the sine model, a one-dimensional tight-binding Hamiltonian featuring hoppings with a sinusoidal dependence on position, and demonstrate the formation of synthetic horizons where electronic wave packets exhibit exponential slowdown. Interestingly, employing the exact transformation between this model and the Harper equation, which describes the eigenstates of a square lattice tight-binding model subjected to a perpendicular magnetic field, we find that analogous semi-classical horizons can emerge in a quantum Hall setup at half-filling for specific values of the magnetic flux. Furthermore, by applying sudden quenches to the sine model's hopping profile, we observe the emergence of thermal states characterized by an Unruh temperature. Our numerical calculations of this temperature reveal a non-universal behavior, suggesting the involvement of physical mechanisms beyond a simple low-energy description.

High-speed, non-volatile tunability is critical for advancing reconfigurable photonic devices used in neuromorphic information processing, sensing, and communication. Despite significant progress in developing phase change and ferroelectric materials, achieving highly efficient, reversible, rapid switching of optical properties has remained a challenge. Recently, sliding ferroelectricity has been discovered in 2D semiconductors, which also host strong excitonic effects. Here, we demonstrate that these materials enable nanosecond ferroelectric switching in the complex refractive index, largely impacting their linear optical responses. The maximum index modulation reaches about 4, resulting in a relative reflectance change exceeding 85%. Both on and off switching occurs within 2.5 nanoseconds, with switching energy at femtojoule levels. The switching mechanism is driven by tuning the excitonic peak splitting of a rhombohedral molybdenum disulfide bilayer in an engineered Coulomb screening environment. This new switching mechanism establishes a new direction for developing high-speed, non-volatile optical memories and highly efficient, compact reconfigurable photonic devices. Additionally, the demonstrated imaging technique offers a rapid method to characterize domains and domain walls in 2D semiconductors with rhombohedral stacking.

The Su-Schrieffer-Heeger (SSH) model, a prime example of a one-dimensional topologically nontrivial insulator, has been extensively studied in flat space-time. In recent times, many studies have been conducted to understand the properties of the low-dimensional quantum matter in curved spacetime, which can mimic the gravitational event horizon and black hole physics. However, the impact of curved spacetime on the topological properties of such systems remains unexplored. Here, we investigate the curved spacetime (CST) version of the SSH model by introducing a position-dependent hopping parameter. We show, using different topological markers, that the CST-SSH model can undergo a topological phase transition. We find that the topologically non-trivial phase can host zero-energy edge modes, but those edge modes are asymmetric, unlike the usual SSH model. Moreover, we find that at the topological transition point, a critical slowdown takes place for zero-energy wave packets near the boundary, indicating the presence of a horizon, and interestingly, if one moves even a slight distance away from the transition point, wave packets start bouncing back and reverse the direction before reaching the horizon. A semiclassical description of the wave packet trajectories also supports these results.

2D semiconductors offer a promising pathway to replace silicon in next-generation electronics. Among their many advantages, 2D materials possess atomically-sharp surfaces and enable scaling the channel thickness down to the monolayer limit. However, these materials exhibit comparatively lower charge carrier mobility and higher contact resistance than 3D semiconductors, making it challenging to realize high-performance devices at scale. In this work, we search for high-mobility 2D materials by combining a high-throughput screening strategy with state-of-the-art calculations based on the ab initio Boltzmann transport equation. Our analysis singles out a known transition metal dichalcogenide, monolayer WS$_2$, as the most promising 2D semiconductor, with the potential to reach ultra-high room-temperature hole mobilities in excess of 1300 cm$^2$/Vs should Ohmic contacts and low defect densities be achieved. Our work also highlights the importance of performing full-blown ab initio transport calculations to achieve predictive accuracy, including spin-orbital couplings, quasiparticle corrections, dipole and quadrupole long-range electron-phonon interactions, as well as scattering by point defects and extended defects.

We investigate aspects of the relation between the quantum geometry of the normal state (NS) and the superconducting phase, through the lens of non-locality. By relating band theory to quantum estimation theory, we derive a direct momentum-dependent relation between quantum geometry and the quantum fluctuations of the position operator. We then investigate two effects of the NS quantum geometry on superconductivity. On the one hand, we present a physical interpretation of the conventional and geometric contributions to the superfluid weight in terms of two different movements of the normal state charge carriers forming the Cooper pairs. The first contribution stems from their center-of-mass motion while the second stems from their zero-point motion, thereby explaining its persistence in flat-band systems. On the other hand, we phenomenologically derive an emergent Darwin term driven by the NS quantum metric. We show its form in one and two-body problems, derive the effective pairing potential in $s$-wave superconductors, and explicit its form in the case of two-dimensional massive Dirac fermions. We thus show that the NS quantum metric screens the pairing interaction and weakens superconductivity, which could be tested experimentally by doping a superconductor. Our work reveals the ambivalent relationship between non-interacting quantum geometry and superconductivity, and possibly in other correlated phases.

Enhancing spin-to-charge (S$\rightarrow$C) conversion efficiency remains a key challenge in spintronic materials research. In this work we investigate the effect of substrate-induced strains onto the S$\rightarrow$C efficiency. On one hand, we analyze strains-induced magnetic anisotropies in yttrium iron garnet (Y$_3$Fe$_5$O$_{12}$, YIG) by comparing the magnetic and structural properties of YIG films grown on Gd$_3$Ga$_5$O$_{12}$ (GGG) and (CaGd)$_3$(MgZrGa)$_5$O$_{12}$ (SGGG) substrates. Differences in lattice mismatch - YIG//GGG ($\eta = -0.06 \%$) and YIG//SGGG ($\eta = -0.83 \%$) - lead to out-of-plane tensile strains in the first case and unexpected compressive strain in the latter. On the other hand, we study the spin injection efficiency on Pt/YIG bilayers evaluated by the Inverse Spin Hall Effect (ISHE). We find that the resulting perpendicular magnetic anisotropy in YIG//SGGG, while not dominant over shape anisotropy, correlates with enhanced ISHE signals as observed in Spin Pumping Ferromagnetic Resonance (SP-FMR) and Spin Seebeck effect (SSE) experiments. Strain engineering proves effective in enhancing spin-to-charge conversion, providing insight into the design of efficient spintronic devices.

Using functional methods, we investigate in a low-temperature liquid, the sound quanta defined by the quantized hydrodynamic fields, under the effects of high-energy processes on the atomic/molecular scale. To obtain in the molecular level the excitation spectra of liquids, we assume that the quantum fields are coupled to an additive delta-correlated in space and time quantum noise field. The hydrodynamic fields are defined in a fluctuating environment. After defining the generating functional of connected correlation fuctions in the presence of the noise field, we perform a functional integral over all noise field configurations. This is done using a formal object inspired by the distributional zeta-function method, named configurational zeta-function. We obtain a new generating functional written in terms of an analytically tractable functional series. Each term of the series describes in the liquid the emergent non-interacting elementary excitations with the usual gapless phonon-like dispersion relation and additional excitations with dispersion relations with gaps in pseudo-momenta space, i.e., tachyonic-like excitations. Furthermore, the Fourier representation of the two-point correlation functions of the model with the contribution coming from all phononic and tachyonic-like fields is presented. Finally, our analysis reveals that the emergent tachyonic-like and phononic excitations yield a distinctive thermodynamic signature - a quadratic temperature dependence of specific heat ($C_V \propto T^2$) at low temperatures, providing a theoretical foundation for experiments in confined and supercooled liquids.

Nonlinearity provides a powerful mechanism for controlling energy localization in structured dynamical systems. In this study, we investigate the emergence of nonlinearity-induced energy localization at the corners of a kagome lattice model featuring onsite cubic nonlinearity. Employing quench dynamics simulations and nonlinear continuation methods, we analyze the temporal and spectral characteristics of localized states under strong nonlinearity. Our results demonstrate the formation of stable, localized corner states, strikingly, even within the parameter regime corresponding to the topologically trivial phase of the underlying linear system, which normally lacks such boundary modes. Furthermore, we identify distinct families of nonlinearity-induced corner states residing within the semi-infinite spectral gap above the bulk bands in both the trivial and nontrivial phases. Stability analysis and nonlinear continuation reveal they are intrinsic nonlinear solutions, fundamentally distinct from perturbations of linear topological or bulk states. These findings elucidate a robust mechanism for generating localized states via nonlinearity, independent of linear topological protection, and provide answers to fundamental questions about the nature of nonlinear topological phenomena. The ability to create tunable, localized states in various spectral regions offers potential applications in energy harvesting, wave manipulation, and advanced signal processing.

We investigate the entanglement properties of a Kondo system undergoing a transition to a state with a quenched magnetic impurity, using the density matrix renormalization group (DMRG) method. We focus on a two-channel spin-1 Kondo impurity with single-ion anisotropy, where a quantum phase transition occurs between two topologically distinct local Fermi liquids. In the fully screened Kondo phase, realized at lower anisotropies, the entangled region surrounding the magnetic impurity mimics the Kondo screening cloud, although its length does not follow the conventional behavior. In contrast, beyond the transition, the system enters a non-Landau Fermi liquid phase with a markedly different entanglement structure: as the impurity is quenched and disentangled from the rest of the system due to the breakdown of the Kondo effect, the two conduction channels coupled only through the impurity develop a significant degree of entanglement with one another. Our findings demonstrate that a quenched magnetic impurity can passively and efficiently mediate entanglement between spatially separated conduction bands.

Current infrared sensing devices are based on costly materials with relatively few viable alternatives known. To identify promising candidate materials for infrared photodetection, we have developed a high-throughput screening methodology based on high-accuracy r$^2$SCAN and HSE calculations in density functional theory. Using this method, we identify ten already synthesized materials between the inverse perovskite family, barium silver pnictide family, the alkaline pnictide family, and ZnSnAs$_2$ as top candidates. Among these, ZnSnAs$_2$ emerges as the most promising candidate due to its experimentally verified band gap of 0.74 eV at 0 K, and its cost-effective synthesis through Bridgman growth. BaAgP also shows potential with an HSE-calculated band gap of 0.64 eV, although further experimental validation is required. Lastly, we discover an additional material, Ca$_3$BiP, which has not been previously synthesized, but exhibits a promising optical spectra and a band gap of 0.56 eV. The method applied in this work is sufficiently general to screen wider bandgap materials in high-throughput and now extended to narrow-band gap materials.

Electron cryo-tomography (cryo-ET) enables 3D imaging of complex, radiation-sensitive structures with molecular detail. However, image contrast from the interference of scattered electrons is nonlinear with atomic density and multiple scattering further complicates interpretation. These effects degrade resolution, particularly in conventional reconstruction algorithms, which assume linearity. Particle averaging can reduce such issues but is unsuitable for heterogeneous or dynamic samples ubiquitous in biology, chemistry, and materials sciences. Here, we develop a phase retrieval-based cryo-ET method, PhaseT3M. We experimentally demonstrate its application to a ~7 nm Co3O4 nanoparticle on ~30 nm carbon substrate, achieving a maximum resolution of 1.6 {\AA}, surpassing conventional limits using standard cryo-TEM equipment. PhaseT3M uses a multislice model for multiple scattering and Bayesian optimization for alignment and computational aberration correction, with a positivity constraint to recover 'missing wedge' information. Applied directly to biological particles, it enhances resolution and reduces artifacts, establishing a new standard for routine 3D imaging of complex, radiation-sensitive materials.

Layered two-dimensional (2D) materials, with their atomic-scale thickness and tunable electronic, optical, and mechanical properties, open many promising pathways to significantly advance modern electronics. The field effect caused by a strong electric field, typically of MV/cm level, applied perpendicular to the material layers, is a highly effective method for controlling these properties. Field effect allows the regulation of the electron flow in transistor channels, improves the photodetector efficiency and spectral range, and facilitates the exploration of novel exotic quantum phenomena in 2D materials. However, existing approaches to induce the field effect in 2D materials utilize circuit-based electrical gating methods fundamentally limited to microwave response rates. Device-compatible ultrafast, sub-picosecond control needed for modern technology and basic science applications still remains a challenge. In this study, we demonstrate such an ultrafast field effect in atomically thin MoS2, an archetypal 2D semiconductor, embedded in a hybrid 3D-2D terahertz nanoantenna structure. This nanoantenna efficiently converts an incident terahertz electric field into the vertical ultrafast gating field in MoS2 while simultaneously enhancing it to the required MV/cm level. We observe the terahertz field effect optically as coherent terahertz-induced Stark shift of characteristic exciton resonances in MoS2. Our results enable novel developments in technology and the fundamental science of 2D materials, where the terahertz field effect is crucial.

Nowadays, the quest for non-Abelian anyons is attracting tremendous attention. In particular, a Majorana quasiparticle has attracted great interest since the non-Abelian anyon is a key particle for topological quantum computation. Much effort has been paid for the quest of the Majorana state in solids, and some candidate material platforms are reported. Among various materials that can host the Majorana state, chiral p-wave superconductor is one of the suitable materials and the iron-based layered superconductor FeTeSe is one of the promising material platforms because its surface can host effective p-wave superconducting state that is analogous to chiral p-wave superconducting state thanks to its topological surface state. Given that a chiral p-wave superconductor possesses spin polarization, detecting the spin polarization can be evidence for the chiral p-wave trait, which results in the existence of Majorana excitation. Here, we show successful detection of the spin polarization at the surface of FeTe0.6Se0.4 in its superconducting state, where the spin polarization is detected via a potentiometric method. Amplitudes of the spin signal exhibit characteristic dependence for temperature and bias current, suggesting detection of spin polarization of the Bogoliubov quasiparticles. Our achievement opens a new avenue to explore topological superconductivity for fault-tolerant quantum computation.

We introduce a multi-species generalization of the asymmetric simple exclusion process (ASEP) with a ``no-passing" constraint, forbidding overtaking, on a one-dimensional open chain. This no-passing rule fragments the Hilbert space into an exponential number of disjoint sectors labeled by the particle sequence, leading to relaxation dynamics that depend sensitively on the initial ordering. We construct exact matrix-product steady states in every particle sequence sector and derive closed-form expressions for the particle-number distribution and two-point particle correlation functions. In the two-species case, we identify a parameter regime where some sectors relax in finite time while others exhibit metastable relaxation dynamics, revealing the coexistence of fast and slow dynamics and strong particle sequence sector dependence. Our results uncover a novel mechanism for non-equilibrium metastability arising from Hilbert space fragmentation in exclusion processes.

The discovery of superconductivity in the bulk nickelates under high pressure is a major advance in physics. The recent observation of superconductivity at ambient pressure in compressively strained bilayer nickelate thin films has now enabled direct characterization of the superconducting phase through angle resolved photoemission spectroscopy (ARPES). Here we present an in-situ ARPES study of compressively strained La$_2$PrNi$_2$O$_7$ films grown by oxide molecular beam epitaxy, and the ozone treated counterparts with an onset T$_c$ of 40 K, supplemented with results from pulsed laser deposition films with similar T$_c$. We resolve a systematic strain-driven electronic band shift with respect to that of bulk crystals, in qualitative agreement with density functional theory (DFT) calculations. However, the strongly renormalized flat 3$d_{z2}$ band shifts a factor of 5-10 smaller than anticipated by DFT. Furthermore, it stays ~70 meV below the Fermi level, contradicting the expectation that superconductivity results from the high density of states of this band at the Fermi level. We also observed a non-trivial k$_z$ dispersion of the cuprate-like 3$d_{x2-y2}$ band. Combined with results from both X-ray diffraction and DFT, we suggest that the strained films are under ~5 GPa effective pressure, considerably larger than the na\"ive expectation from the DFT relaxed structure. Finally, the ~70 meV energy position is intriguingly close to the collective mode coupling more prominently seen in thin films, in the energy range of both oxygen related phonons and the maximum of the spin excitation spectrum.

We present in this work a molecular dynamics study of a size effect relating to the volume fraction of gamma-prime precipitate of edge dislocation motion in a simple model of Nickel superalloys. We model the superalloy as periodically spaced cubic gamma-prime precipitates inside a uniform gamma matrix. We then analyze the motion of paired edge dislocations in the gamma phase when subject to an external shear stress for various volume fractions of the gamma-prime precipitate for a wide range of temperatures, from 300 K to 700 K. While the variation of dislocation velocity is not significant, the critical resolved shear stress is found to exhibit a power law dependence on the volume fraction of the gamma-prime precipitate with two distinct regimes which have similar exponent but markedly different prefactors; we also observe that this two-regime behavior remains true across a wide range of temperatures. We present a detailed analysis of this behavior and reduce it to a linear dependence of the critical resolved shear stress on the length of the gamma-prime precipitate along the direction of dislocation motion. We further identify the critical length scale underlying the transition between the two observed regimes as the total core width of the paired dislocations in a pure gamma-prime system, which includes in addition to the complex stacking fault separating the partials of the paired dislocations the width of the anti-phase boundary that is formed between the super-dislocations. The results presented in this work provides new details on the strengthening effect of gamma-prime precipitates in nickel superalloys and also has important implications for larger scale dislocation dynamics studies for nickel superalloys.

We report a comprehensive investigation of the physical properties of LuOs3B2, characterized by an ideal Os-based kagome lattice. Resistivity and magnetization measurements confirm the emergence of type-II bulk superconductivity with a critical temperature Tc=4.63 K. The specific heat jump and the calculated electron-phonon coupling parameter support a moderately coupled superconducting state. Electron correlation effects are supported by the enhanced Wilson ratios. First-principles calculations reveal hallmark features of kagome band structure, including Dirac points, van Hove singularities, and quasi-flat bands, primarily derived from the Os d orbitals. The inclusion of spin-orbit coupling opens a gap at the Dirac points, significantly altering the electronic properties. Furthermore, the superconductivity and electronic properties of isomorphic compounds are discussed. This work provides a thorough exploration of the superconducting and normal states of LuOs3B2, deepening the understanding of kagome superconductors.

Using Density functional theory and non-equilibrium Green's function formalism, spin-dependent electron transport in Fe/MoxCr1-xS2/Fe magnetic tunnel junction is studied. Spin-transport for different thicknesses (1, 3, 5, and 7 layers) of the spacer MoS2 and for two different surface orientations of the Fe electrode, the Fe(001) and Fe(111) surface and the effect of substitutional doping of magnetic impurity Cr on the spin-transport of the junctions is investigated. The electronic structure of the heterostructure shows presence of metal induced states in the semiconducting MoS2 at the Fe/MoS2 interface and the effect of the interface is limited to the first two layers of MoS2 from the interface. The I-V characteristics of the junctions for the monolayer and three-layer MoS2 spacer show linear behaviour due to the metallic nature of the junction. The tunneling nature of the junction is observed for the thicker junctions with five-layer and seven-layer spacers. With the introduction of magnetic impurity, we have shown that spin-polarisation in the spacer is improved, thus increasing the spin-polarised current. The Cr-defect states are observed below the conduction band and the Cr-doped devices are stable up to a bias of 0.5V. The close packed Fe(111) surface is better electrode material for tunneling of electrons through the junction compared to the Fe(001) surface due to lower surface energy and reduced transmission.

Small and wide angle x-ray scattering tensor tomography are powerful methods for studying anisotropic nanostructures in a volume-resolved manner, and are becoming increasingly available to users of synchrotron facilities. The analysis of such experiments requires, however, advanced procedures and algorithms, which creates a barrier for the wider adoption of these techniques. Here, in response to this challenge, we introduce the mumott package. It is written in Python with computationally demanding tasks handled via just-in-time compilation using both CPU and GPU resources. The package is being developed with a focus on usability and extensibility, while achieving a high computational efficiency. Following a short introduction to the common workflow, we review key features, outline the underlying object-oriented framework, and demonstrate the computational performance. By developing the mumott package and making it generally available, we hope to lower the threshold for the adoption of tensor tomography and to make these techniques accessible to a larger research community.

X-ray magnetic circular dichroism (XMCD) and X-ray magnetic linear dichroism (XMLD) are powerful spectroscopic techniques for probing magnetic properties in solids. In this study, we revisit the XMCD and XMLD sum rules within a complete magnetic multipole basis that incorporates both spinless and spinful multipoles. We demonstrate that these multipoles can be clearly distinguished and individually detected through the sum-rule formalism. Within this framework, the anisotropic magnetic dipole term is naturally derived in XMCD, offering a microscopic origin for ferromagnetic-like behavior in antiferromagnets. Furthermore, we derive the sum rules for out-of-plane and in-plane XMLD regarding electric quadrupole contributions defined based on the complete multipole basis. Our theoretical approach provides a unified, symmetry-consistent framework for analyzing dichroic signals in various magnetic materials. These findings deepen the understanding of XMCD and XMLD and open pathways to exploring complex magnetic structures and spin-orbit coupling effects in emergent magnetic materials.

The drive for solid-state heating and cooling technologies is fuelled by their potential for enhanced sustainability and environmental impact compared to traditional vapour compression devices. The recent discovery of colossal barocaloric (BC) effects in the plastic crystal (PC) neopentyl glycol (NPG) has highlighted PCs as promising candidates for future solid-state thermal management. However, achieving optimal operational temperatures, low-pressure requirements, and substantial entropy changes in a single material remains challenging. Here, we demonstrate a strategy to address these constraints by forming a ternary solid solution of neopentyl PCs: NPG, pentaglycerine (PG) and pentaerythritol (PE). Notably, by including only a small quantity (2%) of the third component, we observe a seven-fold increase in reversible isothermal entropy change (|{\Delta}Sit,rev| = 13.4 J kg-1 K-1) and twenty-fold increase in operational temperature span ({\Delta}Tspan = 18 K) at pressures of 1 kbar, compared to pure NPG. The origin of these enhancements is revealed by quasielastic neutron scattering and synchrotron powder x-ray diffraction. We find a reduction in the activation energies of the rotational modes associated with the main entropic component of the BC effect, linked to a weakening of the intermolecular hydrogen bond network. This is proposed to improve the phase transition reversibility and operational temperature span by facilitating a broadened first-order phase transition, characterised by a significant phase co-existence region. These findings suggest an effective strategy for practicable molecular BCs, which is to design solid solutions that exploit the large compositional phase space of multi-component molecular systems.

We theoretically investigate the inverse Faraday effect (IFE), a phenomenon where circularly-polarized light induces a magnetic moment, in a multiorbital metallic system. We demonstrate that the total magnetic moment can be decomposed into several contributions in multiorbital tight-binding models. In particular, we reveal that the electric dipole moment of Wannier orbitals also contributes to the orbital magnetic moment, which is not included in the conventional expression for the orbital magnetic moment in lattice systems. To account for all possible contributions, we adopt an $s$-$p$ tight-binding system as a minimal model for the IFE. Using an analytical approach based on the Schrieffer-Wolff transformation, we clarify the physical origins of these contributions. Additionally, we quantitatively evaluate each contribution on an equal footing through a numerical approach based on the Floquet formalism. Our results reveal that the orbital magnetic moment exhibits a significantly larger response compared to the spin magnetic moment, with all contributions to the orbital magnetic moment being comparable in magnitude. These findings highlight the essential role of orbital degrees of freedom in the IFE.

The conversion of $\mathrm{CO_2}$ into useful products such as methanol is a key strategy for abating climate change and our dependence on fossil fuels. Developing new catalysts for this process is costly and time-consuming and can thus benefit from computational exploration of possible active sites. However, this is complicated by the complexity of the materials and reaction networks. Here, we present a workflow for exploring transition states of elementary reaction steps at inverse catalysts, which is based on the training of a neural network-based machine learning interatomic potential. We focus on the crucial formate intermediate and its formation over nanoclusters of indium oxide supported on Cu(111). The speedup compared to an approach purely based on density functional theory allows us to probe a wide variety of active sites found at nanoclusters of different sizes and stoichiometries. Analysis of the obtained set of transition state geometries reveals different structure--activity trends at the edge or interior of the nanoclusters. Furthermore, the identified geometries allow for the breaking of linear scaling relations, which could be a key underlying reason for the excellent catalytic performance of inverse catalysts observed in experiments.

We investigate the non-equilibrium dynamics of active bead-spring critical percolation clusters under the action of monopolar and dipolar forces. Previously, Langevin dynamics simulations of Rouse-type dynamics were performed on a deterministic fractal -- the Sierpinski gasket -- and combined with analytical theory [Chaos {\bf 34}, 113107 (2024)]. To study disordered fractals, we use here the critical (bond) percolation infinite cluster of square and triangular lattices, where beads (occupying nodes) are connected by harmonic springs. Two types of active stochastic forces, modeled as random telegraph processes, are considered: force monopoles, acting on individual nodes in random directions, and force dipoles, where extensile or contractile forces act between pairs of nodes, forming dipole links. A dynamical steady state is reached where the network is dynamically swelled for force monopoles. The time-averaged mean square displacement (MSD) shows sub-diffusive behavior at intermediate times longer than the force correlation time, whose anomalous exponent is solely controlled by the spectral dimension $(d_s)$ of the fractal network yielding MSD $\sim t^{\nu}$, with $\nu=1-\frac{d_s}{2}$, similar to the thermal system and in accord with the general analytic theory. In contrast, dipolar forces require a diverging time to reach a steady state, depending on the fraction of dipoles, and lead to network shrinkage. Within a quasi-steady-state assumption, we find a saturation behavior at the same temporal regime. Thereafter, a second ballistic-like rise is observed for networks with a low fraction of dipole forces, followed by a linear, diffusive increase. The second ballistic rise is, however, absent in networks fully occupied with force dipoles. These two behaviors are argued to result from local rotations of nodes, which are either persistent or fluctuating.

Precise understanding of the electronic structures of optically dark triplet-triplet multiexcitons that are the intermediate states in singlet fission (SF) continues to be a challenge. This is particularly true for intramolecular singlet fission (iSF) chromophores, that are oligomers of large monomer molecules. We have performed quantum many-body calculations of the complete set of excited states relevant to iSF in Pentacene-(Tetracene)2-Pentacene oligomers, consisting of two terminal pentacene monomers linked by two tetracene monomers. Our computations use an exciton basis that gives physical pictorial descriptions of all eigenstates, and are performed over an active space of twenty-eight monomer molecular orbitals, including configuration interaction with all relevant quadruple excitations within the active space, thereby ensuring very high precision. We discuss the many-electron structures of the optical predominantly intramonomer spin-singlets, intermonomer charge-transfer excitations, and most importantly, the complete set of low energy covalent triplet-triplet multiexcitons. We are able to explain the weak binding energy of the pentacene-tetracene triplet-triplet eigenstate that is generated following photoexcitation. We explain the increase in lifetime with increasing numbers of tetracene monomers of the transient absorption associated with contiguous pentacene-tetracene triplet-triplet in this family of oligomers. We are consequently able to give a pictorial description of the triplet separation following generation of the initial triplet-triplet, leading to a state with individual triplets occupying only the two pentacene monomers. We expect many applications of our theoretical approach to triplet separation.

Brownian motion in periodic potentials has been widely investigated in statistical physics and related interdisciplinary fields. In the overdamped regime, it has been well-known that the diffusion constant $D^*$ is given by the Lifson-Jackson (LJ) formula. With a tilted potential, this model can exhibit giant diffusion. In this work, we start from the basic argument that since any quasi-periodic potential can be approximated accurately using a periodic potential, this formula and the associated physics should also apply to the quasi-periodic potential after some proper redefinition. We derive $D^*$ from the Smoluchowski equation using the fact that its asymptotic solution is a product of a Boltzmann weight and a Gaussian envelope function. Then we analytically calculate $D^*$ in terms of Bessel functions. Finally, we study the giant diffusion with quasi-periodic potentials, generalize the corresponding formula to the condition with tilted potential under the same argument, and calculate $D^*$ analytically. This work generalizes the Brownian motion from periodic potentials to the much broader quasi-periodic potentials, which should have applications in interdisciplinary fields in physics, chemistry, engineering, and life sciences.

A major question in the field of femtosecond laser-induced demagnetization is whereto the angular momentum lost by the electrons is transferred. Recent ultrafast electron diffraction measurements [Tauchert \textit{et al.}, Nature {\bf 602}, 73 (2022)] suggest that this angular momentum is transferred to the rotational motion of atoms on a sub-picosecond timescale, but a theory confirmation of this proposition has yet to be given. Here we investigate the coupled electron-nuclear dynamics during ultrafast demagnetization of L1$_0$ FePt, using Ehrenfest nuclear dynamics simulations combined with the time-dependent density functional theory (TDDFT) framework. We demonstrate that atomic rotations appear, i.e., the generation of phonons carrying finite angular momentum following ultrafast demagnetization. We further show that both ultrafast demagnetization and the generation of phonons with angular momentum arise from symmetry constraints imposed by the spin-orbit coupling, thus providing insight in spin-phonon interaction at ultrafast timescales.

We report on a switchable emulsion droplet microswimmer by utilizing a temperature-dependent transition of the droplet phase. The droplets, made from a liquid crystalline (LC) smectic phase material ($T =$ 25 $^{\circ}$C), self-propel only in their nematic and isotropic phases at elevated temperatures ($T\ge$ 33.5 $^{\circ}$C). This transition between motile and non-motile states is fully reversible - in the motile state, the droplets exhibit persistent motion and directional memory over multiple heating-cooling cycles. Further, we distinguish the state of rest from the state of motion by characterizing the chemical and hydrodynamic fields of the droplets. Next, we map the motility behaviour of the droplets across varying surfactant concentrations and temperatures, observing that swimming occurs only at sufficiently high surfactant concentrations above and temperatures above the smectic-nematic phase transition temperature $\textit{i.e.}$ $T\ge$ 33.5 $^{\circ}$C. Our work envisions the potential of LC emulsion droplets as switchable microswimmers.

The link between composition, microstructure and mechanics of NASH and KASH gels is elusive, even in pure metakaolin-based geopolymes. This article exploits molecular mechanics, coarse-grained nanomechanics and micromechanics, to interpret new experimental results from microscopy, porosimetry and nanoindentation. KASH displays a finer nanogranular structure than NASH (3 vs 30 nm particle diameters, 5 vs 50 nm average pore diameters), higher skeletal density (2.3 vs 2.02 g/cm$^3$), nanoindentation moduli (9.21 vs 7.5 GPa) and hardness (0.56 vs 0.37 GPa) despite a higher total porosity (0.48-0.53 vs 0.38). This suggests a stiffer and stronger solid skeleton for KASH, confirmed through predictive molecular dynamics simulations on recent and new models of NASH and KASH. The atomistic simulations inform mechanical interactions for new, coarse-grained, particle-based models of NASH and KASH. The resulting simulations predict the nanoindentation result that KASH is stiffer than equally porous NASH and the impact of formation eigenstresses on elastic moduli.

We propose a family of modulated honeycomb lattices, a class of quasiperiodic tilings characterized by the metallic mean. These lattices consist of six distinct hexagonal prototiles with two edge lengths, $\ell$ and $s$, and can be regarded as a continuous deformation of the honeycomb lattice. The structural properties are examined through their substitution rules. To study the electronic properties, we construct a tight-binding model on the tilings, introducing two types of hopping integrals, $t_L$ and $t_S$, corresponding to the two edge lengths, $\ell$ and $s$, respectively. By diagonalizing the Hamiltonian on these quasiperiodic tilings, we compute the corresponding density of states (DOS). Our analysis reveals that the introduction of quasiperiodicity in the distribution of hopping integrals induces a spiky structure in the DOS at higher energies, while the linear DOS at low energies ($E\sim 0$) remains robust. This contrasts with the smooth DOS in the disordered tight-binding model, where two types of hopping integrals are randomly distributed according to a given ratio. Furthermore, we study the magnetic properties of the Hubbard model on modulated honeycomb lattices by means of real-space Hartree approximations. A magnetic phase transition occurs at a finite interaction strength due to the absence of the noninteracting DOS at the Fermi level. When $t_L\sim t_S$, the phase transition point is primarily governed by the linear DOS. However, far from the condition $t_L=t_S$, the quasiperiodic structure plays a significant role in reducing the critical interaction strength, which is in contrast to the disordered system. Using perpendicular space analysis, we demonstrate that sublattice asymmetry inherent in the quasiperiodic tilings emerges in the magnetic profile, providing insights into the interplay between quasiperiodicity and electronic correlations.

Van der Waals (vdW) layered materials have gained significant attention owing to their distinctive structure and unique properties. The weak interlayer bonding in vdW layered materials enables guest atom intercalation, allowing precise tuning of their physical and chemical properties. In this work, a ternary compound, NixIn2Se3 (x = 0-0.3), with Ni randomly occupying the interlayers of In2Se3, was synthesized via an intercalation route driven by electron injection. The intercalated Ni atoms act as anchor points within the interlayer of In2Se3, which effectively suppresses the phase transition of In2Se3 at elevated temperatures. Furthermore, the disordered Ni intercalation significantly enhanced the electrical conductivity of In2Se3 through electron injection, while reducing the thermal conductivity due to the interlayer phonon scattering, leading to an improved thermoelectric performance. For instance, the thermoelectric figure of merit (ZT) of Ni0.3In2Se3 increased by 86% (in-plane) and 222% (out-of-plane) compared to In2Se3 at 500 oC. These findings not only provide an effective strategy to enhance the performance of layered thermoelectric materials, but also demonstrate the potential of intercalation chemistry for expanding the application scope of van der Waals (vdW) layered materials.

On the basis of the application of the (Onsager) second-virial density functional theory to an artificial system that is so designed as to be the best promoter of a ``splay(-bend)'' nematic phase, it is argued that this ``modulated'' nematic phase cannot exist.

The kagome material AV$_3$Sb$_5$ exhibits multiple exotic orders, including an unconventional charge density wave (CDW). Elucidating the underlying mechanism behind the CDW transition is crucial for unraveling the complex interactions among these phases. However, the driving force of the CDW remains a topic of debate due to the intertwined interactions among the system's various excitations. Here we investigated the CDW transition in KV$_3$Sb$_5$ by isolating the ultrafast electronic phase transition using time- and angleresolved photoemission spectroscopy. An ultrafast electronic phase transition was observed at a critical photoexcitation fluence, Fc, without reduction in CDW lattice-distortion-induced band folding. This folded band persisted up to 150 K under equilibrium heating, well above the CDW condensation temperature of Tc = 78 K. Notably, the pump-induced band shifts at Fc were comparable to those caused by thermal effects at Tc. These findings suggest that in KV$_3$Sb$_5$, a fluctuating lattice-driven in-plane CDW emerges above 150 K, with out-of-plane electronic correlations leading to the $2\times2 \times 2$ CDW near Tc, offering key insights into the interplay between the electronic and structural dynamics in AV$_3$Sb$_5$.

This work presents a finite-strain version of an established three-dimensional constitutive model for polycrystalline shape memory alloys (SMA) that is able to account for the large deformations and rotations that SMA components may undergo. The model is constructed by applying the logarithmic strain space approach to the original small-strain model, which was formulated within the Generalized Standard Materials framework and features a refined dissipation (rate) function. Additionally, the free energy function is augmented to be more versatile in capturing the transformation kinetics. The model is implemented into finite element software. To demonstrate the model performance and validate the implementation, material parameters are fitted to the experimental data of two SMA, and two computational simulations of SMA components are conducted. The applied approach is highly flexible from the perspective of the future incorporation of other phenomena, e.g., irreversibility associated with plasticity, into the model.

Localization of wave functions in the disordered models can be characterized by the Lyapunov exponent, which is zero in the extended phase and nonzero in the localized phase. Previous studies have shown that this exponent is a smooth function of eigenenergy in the same phase, thus its non-smoothness can serve as strong evidence to determine the phase transition from the extended phase to the localized phase. However, logically, there is no fundamental reason that prohibits this Lyapunov exponent from being non-smooth in the localized phase. In this work, we show that if the localization centers are inhomogeneous in the whole chain and if the system possesses (at least) two different localization modes, the Lyapunov exponent can become non-smooth in the localized phase at the boundaries between the different localization modes. We demonstrate these results using several slowly varying models and show that the singularities of density of states are essential to these non-smoothness, according to the Thouless formula. These results can be generalized to higher-dimensional models, suggesting the possible delicate structures in the localized phase, which can revise our understanding of localization hence greatly advance our comprehension of Anderson localization.

Strong electronic correlation can lead to insulating behavior and to the opening of large optical gaps, even in materials with partly filled valence shells. Although the non-equilibrium optical response encodes both local (quasi atomic) and collective (long range) responses, optical spectroscopy is usually more sensitive to the latter. Resonant x-ray techniques are better suited to investigate the quasi-atomic properties of correlated solids. Using time-resolved resonant inelastic x-ray scattering (RIXS), here we study the ultrafast non-equilibrium processes in NiO following photo-excitation by ultraviolet photons with energy exceeding the optical gap. We observe the creation of charge-transfer excitons that decay with a time constant of about 2\,ps, while itinerant photo-doping persists for tens of picoseconds. Following our discovery, which establishes time-resolved high-resolution RIXS as a powerful tool for the study of transient phenomena in condensed matter, the possible presence of charge-transfer excitons will need to be considered when interpreting optical pump-probe experiments on correlated quantum materials.

The second-harmonic Hall technique is a widely used, sensitive method for studying the spin-orbit torques generated by charge current. It exploits the dependence of the Hall resistance on the magnetization direction, although thermal phenomena also contribute. Historically, deviations from the expected magnetic field dependence have usually been neglected. Based on our studies on permalloy/platinum bilayers, we show that a unidirectional magnetoresistance - known to appear in the second-harmonic longitudinal resistance - also appears in the Hall data, and that describing the results in a wide field range with these contributions is essential to accurately estimate the torques.

In this work, a thorough exploration has been carried out to unravel the role of electron-phonon interaction (EPI) in a Bernevig-Hughes-Zhang (BHZ) quantum spin Hall (QSH) insulator subjected to a time-periodic step drive. It is observed that upon inclusion of the EPI, the system demonstrates emergent Floquet QSH (FQSH) phases and several topological phase transitions therein, mediated solely by the interaction strength. Quite intriguingly, the emergence of topological zero ($\pi$) modes in the bulk that remains otherwise gapless in the vicinity of the $\pi$ (zero) energy sector is observed, thus serving as a prime candidate of robust topology in gapless systems. With other invariants being found to be deficient in characterizing such coexistent phases, a spectral localizer (SL) is employed, which distinctly ascertains the nature of the (zero or $\pi$) edge modes. Following the SL prescription, a real-space Chern marker computed by us further provides support to such \textit{gapless} Floquet topological scenario. Our results can be realized in advanced optical setups that may underscore the importance of EPI-induced Floquet features.

Non-Abelian gauge fields, characterized by their non-commutative symmetry groups, shape physical laws from the Standard Model to emergent topological matter for quantum computation. Here we find that moir\'e exciton dimers (biexcitons) in twisted bilayer MoTe$_2$ are governed by a genuine non-Abelian lattice gauge field. These dipolar-bound exciton dimers, formed on bonds of the honeycomb moir\'e superlattice, exhibit three quadrupole configurations organized into a Kagome lattice geometry, on which the valley-flip biexciton hoppings through electron-hole Coulomb exchange act as link variables of the non-Abelian lattice gauge theory. The emergence of gauge structure here is a new possibility for composite particles, where the moir\'e electronic structure and interactions between the electron and hole constituents jointly enforce the underlying geometric constraint. The quadrupole nature of biexciton further makes possible local gate controls to isolate designated pathways from the extended lattice for exploiting consequences of non-commutative gauge structure including the genuine non-Abelian Aharonov-Bohm effect. This also provides a new approach for quantum manipulation of excitonic valley qubit. We show path interference on a simplest loop can deterministically transform the computational basis states into Bell states.

In this study, we have investigated and compared the effect of hydrostatic pressure up to ~20 kbar on the transport properties of ZrTe5 single crystals grown by chemical vapor transport (CVT) and flux methods. With the application of pressure, the electrical resistivity Rho(T) and thermopower S(T) of both crystals were found to increase in the whole temperature range unlike the other known thermoelectric materials, such as Bi2Te3, SnSe etc. This observation is supported by the complementary first-principles band structure calculation as the application of pressure widens the direct bandgap at {\Gamma} point. Moreover, the analysis of the pressure dependent magneto-transport and Shubnikov de-Hass oscillation results revealed an increase in carrier concentration and effective mass along with the reduction of mobility as pressure rises. Furthermore, with the application of pressure, the flux-grown ZrTe5 crystals display a transition from unipolar to bipolar charge transport as evidenced by the emergence of resistivity peak at T* under high pressure, unlike the CVT-grown ZrTe5 crystals where the bipolar charge transport near its characteristic resistivity peak (Tp) remains unaffected.

Solid-state ion conductors hold promise as next generation battery materials. To realize their full potential, an understanding of atomic-scale ion conduction mechanisms is needed, including ionic and electronic degrees of freedom. Molecular simulations can create such an understanding, however, including a description of electronic structure necessitates computationally expensive methods that limit their application to small scales. We examine an alternative approach, in which neural network models are used to efficiently sample ionic configurations and dynamics at ab initio accuracy. Then, these configurations are used to determine electronic properties in a post-processing step. We demonstrate this approach by modeling the superionic phase of AgI, in which cation diffusion is coupled to rotational motion of local electron density on the surrounding iodide ions, termed electronic paddlewheels. The neural network potential can capture the many-body effects of electronic paddlewheels on ionic dynamics, but classical force field models cannot. Through an analysis rooted the generalized Langevin equation framework, we find that electronic paddlewheels have a significant impact on the time-dependent friction experienced by a mobile cation. Our approach will enable investigations of electronic fluctuations in materials on large length and time scales, and ultimately the control of ion dynamics through electronic paddlewheels.

Magnetoelectric (ME) multiferroics enable efficient interconversion of electrical and magnetic signals, offering pathways toward substantial reduction of power consumption in next-generation computing and information technologies. However, despite decades of research, the persistence of ME coupling at room-temperature, an indispensable feature for practical applications, remains exceedingly rare in single-phase materials, due to symmetry constraints imposed by magnetic point groups and competing electronic requirements for ferroelectricity and magnetism. Here we report the coexistence of ferroelectricity and ferromagnetism at 780 K and a strong ME coupling with a converse ME coupling coefficient up to 498 ps/m at room-temperature in strontium titanate by dedicated vacancy engineering. The asymmetric distribution of oxygen vacancies surrounding titanium vacancies enables atomic displacement of titanium and charge injection, providing joint origin for ferroelectricity and ferromagnetism, as confirmed by atomic-scale structural analysis and first-principles calculations. The mechanism of ME coupling is offered as the hopping of oxygen vacancies under electric fields, which leads to the rearrangement of electronic configuration. Our work opens an avenue for designing multiferroics, overcoming the long-standing scarcity of room-temperature single-phase multiferroics.

We study the properties of discrete-time random walks on networks formed by randomly interconnected cliques, namely, random networks of cliques. Our purpose is to derive the parameters that define the network structure -- specifically, the distribution of clique size and the abundance of inter-clique links -- from the observation of selected statistical features along the random walk. To this end, we apply a Bayesian approach based on recording the times spent by the walker inside successively visited cliques. The procedure is illustrated with some numerical examples of diverse complexity, where the relevant structural parameters are successfully recovered.

Electronic interferometers in the quantum Hall regime are one of the best tools to study the statistical properties of localized quasiparticles in the topologically protected bulk. However, since their behavior is probed via chiral edge modes, bulk-to-edge and inter-edge interactions are two important effects that affect the observations. Moreover, almost all kinds of interferometers heavily rely on a pair of high-quality quantum point contacts where the presence of impurities significantly modifies the behavior of such constrictions, which in turn can alter the outcome of the measurements. Antidots, potential hills in the quantum Hall regime, are particularly valuable in this context, as they overcome the geometric limitations of conventional geometries and act as controlled impurities within a quantum point contact. Furthermore, antidots allow for quasiparticle charge detection through simple conductance measurements, replacing the need for complex techniques such as shot noise. Here, we use a gate-defined bilayer graphene antidot, operated in the Coulomb-dominated regime. By varying the antidot potential, we can tune inter-edge interactions, enabling a crossover from a single-dot to a double-dot behavior. In the latter, strong coupling between the two edge states leads to edge-state pairing, resulting in a measured doubling of the tunneling charge. We find that in certain regimes, the inter-edge coupling completely dominates over other energy scales of the system, overshadowing the interference effects these devices are mainly designed to probe. These results highlight the significant role of inter-edge interactions and establish antidots as a versatile platform for exploring quantum Hall interferometry.

Within the framework of 3d-4f molecular magnets, the most thoroughly investigated architecture is that of butterfly-shaped coordination clusters as it provides an ideal testbed to study fundamental magnetic interactions. Here, we report the synthesis and characterisation of a series of isostructural V$^{\rm III}_2$Ln$^{\rm III}_2$ butterfly complexes, where Ln = Y (1Y), Tb (2Tb), Dy (3Dy), Ho (4Ho), Er (5Er), Tm (6Tm), Yb (7Yb), which extends the previous study on isostructural butterflies with Cr$^{\rm III}$, Mn$^{\rm III}$ and Fe$^{\rm III}$. In zero external field, compounds 2Tb, 3Dy and 4Ho show clear maxima in the out-of-phase component of the ac susceptibility whereas small magnetic fields are needed to suppress quantum tunneling in 6Tm. Combined high-field electron paramagnetic resonance spectroscopy and magnetisation measurements unambiguously reveal an easy-plane anisotropy of the V$^{\rm III}$ ion and antiferromagnetic Ising-like 3d-4f exchange couplings. The strength of $J_{\rm 3d-4f}$ is shown to decrease upon variation of the 4f ion from Tb to Ho, while increasing antiferromagnetic interaction can be observed from Ho to Tm. The exact inverse chemical trend is found for the relative angle between the 3d and 4f main anisotropy axes, which highlights the important role of the lanthanide 4f electron distribution anisotropy for 3d-4f exchange.

The flows of tissues of epithelial cells often involve T1 transitions. These neighbour exchanges are irreversible rearrangements crossing an energy barrier. Here, by an exact geometric construction, I determine this energy barrier for general, isolated T1 transitions dominated by line tensions. I show how deviations from regular cell packing reduce this energy barrier, but find that line tension fluctuations increase it on average. By another exact construction, I show how nonlinear tensions in vertex models of epithelial tissues also resist T1 transitions. My results thus form the basis for coarse-grained descriptions of cell neighbour exchanges in continuum models of epithelia.

Rashba spin-orbit coupling significantly modifies the electronic band structure in two-dimensional (2D) van der Waals (vdW) heterobilayers, which may enhance their thermoelectric (TE) properties. In this study, we use first-principles calculations and Boltzmann transport theory to explore the strain effect on the TE performance of the 2D vdW heterobilayer MoTe$_{2}$/PtS$_{2}$. A strong Rashba spin-splitting is observed in the valence band, resulting in an increase in the Seebeck coefficient for p-type. The lattice thermal conductivity of MoTe$_{2}$/PtS$_{2}$ is remarkably low about of 0.6 Wm$^{-1}$K$^{-1}$ at $T = 300$ K due to large anharmonic scattering. Furthermore, biaxial strain enhances the power factor (PF) by introducing band convergence. At a strain of 2\%, the optimal PF for the n-type material reaches 170 $\mu$W/cmK$^{2}$, indicating approximately 84.78\% increase compared to the unstrained state (92 $\mu$W/cmK$^{2}$). Given the low lattice thermal conductivity, the optimized figure of merit $ZT$ achieves up to 0.88 at 900 K for n-type. Our findings indicate that MoTe$_{2}$/PtS$_{2}$ is a highly promising candidate for 2D heterobilayer TE materials, owing to its strong Rashba splitting and significant anharmonicity.

Phase-field fracture models provide a powerful approach to modeling fracture, potentially enabling the unguided prediction of crack growth in complex patterns. To ensure that only tensile stresses and not compressive stresses drive crack growth, several models have been proposed that aim to distinguish between compressive and tensile loads. However, these models have a critical shortcoming: they do not account for the crack direction, and hence they cannot distinguish between crack-normal tensile stresses that drive crack growth and crack-parallel stresses that do not. In this study, we apply a phase-field fracture model, developed in our earlier work, that uses the crack direction to distinguish crack-parallel stresses from crack-normal stresses. This provides a transparent energetic formulation that drives cracks to grow in when crack faces open or slide past each other, while the cracks respond like the intact solid when the crack faces contact under normal compressive loads. We compare our approach against two widely used approaches, Spectral splitting and the Volumetric-Deviatoric splitting, and find that these predict unphysical crack growth and unphysical stress concentrations under loading conditions in which these should not occur. Specifically, we show that the splitting models predict spurious crack growth and stress concentration under pure crack-parallel normal stresses. However, our formulation, which resolves the crack-parallel stresses from the crack-normal stresses, predicts these correctly.

The effect of an additional quasi-resonant drive on the dynamics of the ring-shaped incoherently pumped polariton condensates carrying angular momentum (vorticity) is studied theoretically. Numerical simulations of the 2D and 1D Gross-Pitaevskii equations show that the difference of the topological charges(vorticities) $\Delta n$ of the condensate and the quasi-resonant coherent drive plays a crucial role in the synchronization dynamics. It is shown that in an axially symmetric system, synchronization can only occur if $|\Delta n| = 0$, whereas in the other cases the phase of the condensate cannot be locked to the phase of the coherent drive. To explain this effect observed in the numerical simulations a perturbation theory is developed. The theory shows that the phase slip between the condensate and the coherent drive can be understood in terms of the motion of 2$\pi$ kinks. It is shown that the breaking of the axial symmetry can stop the motion of the kinks, allowing the phase locking of the condensate to the coherent drive.

We investigate the behavior of the quantized Hall conductivity in a two-dimensional quantum system under rotating effects, a uniform magnetic field, and an Aharonov-Bohm (AB) flux tube. By varying the angular velocity and the AB flux, we analyze their impact on the formation, shifting, and structure of quantized Hall plateaus. Our results reveal that rotation modifies the energy spectrum, leading to slight shifts in the plateau positions and variations in their widths. Additionally, we identify Aharonov-Bohm-type oscillations in $\sigma_{\text{Hall}}$, which become more pronounced for lower values of the cyclotron frequency $\omega_c$, indicating enhanced quantum interference effects in the low-field regime. These oscillations are further modulated by $\Omega$, affecting their periodicity and amplitude. The interplay between the confinement frequency $\omega_0$, the cyclotron frequency $\omega_c$, and the rotational effects plays a crucial role in determining the overall behavior of $\sigma_{\text{Hall}}$. Our findings provide insights into the interplay between rotation, magnetic field, and quantum interference effects, which are relevant for experimental investigations of quantum Hall systems in rotating systems.

So-called polar liquid crystals possess spontaneous long-range mutual orientation of their electric dipole moments, conferring bulk polarity to fluid phases of matter. The combination of polarity and fluidity leads to complex phase behaviour, and rich new physics, yet the limited understanding around how specific molecular features generate long-range polar ordering in a fluid is a hindrance to development of new materials. In this work, we introduce a computational framework that probes the bimolecular potential energy landscape of candidate molecules, enabling us to dissect the role of directional intermolecular interactions in establishing polar order. In closely related families of materials we find conflicting preferences for (anti)parallel ordering which can be accounted for by specific interactions between molecules. Thus, our results allow us to argue that the presence (or absence) of polar order is a product of specific molecular features and strong directional intermolecular interactions rather than being simply a product of dipole-dipole forces. The design principles established can be leveraged to developing new polar liquid crystalline materials.

We demonstrate the successful simulation of $\sqrt{Z}$-, $\sqrt{X}$- and $X$-quantum gates using Majorana zero modes (MZMs) that emerge in magnetic vortices located in topological superconductors. We compute the transition probabilities and geometric phase differences accounting for the full many-body dynamics and show that qubit states can be read out by fusing the vortex core MZMs and measuring the resulting charge density. We visualize the gate processes using the time- and energy-dependent non-equilibrium local density of states. Our results demonstrate the feasibility of employing vortex core MZMs for the realization of fault-tolerant topological quantum computing.

We investigate the eigenstates, that is, the wavefunctions of Rydberg excitons in cuprous oxide quantum wells and derive expressions relating them to the oscillator strengths of different exciton states. Using the B-spline expansion, we compute the wavefunctions in coordinate space and estimate the oscillator strengths. The symmetry properties of the states and the non-separability of the wavefunctions are illustrated. Wavefunctions associated with resonances above the scattering threshold, in particular those of bound states in the continuum as well as their partner states, are also given.

One route to the control of quantum magnetism at ultrafast timescales is magnetophononics, the modulation of magnetic interactions by coherently driven lattice excitations. Theoretical studies of a gapped quantum magnet subject to continuous, single-frequency driving of one strongly coupled phonon mode find intriguing phenomena including mutually repelling phonon-bitriplon excitations and global renormalization of the spin excitation spectrum. Because experiments are performed with ultrashort pulses that contain a wide range of driving frequencies, we investigate phonon-bitriplon physics under pulsed laser driving. We use the equations of motion to compute the transient response of the driven and dissipative spin-phonon system, which we characterize using the phonon displacement, phonon number, and triplon occupations. In the Fourier transforms of each quantity we discover a low-frequency energetic oscillation between the lattice and spin sectors, which is an intrinsically nonequilibrium collective mode, and demonstrate its origin as a beating between mutually repelling composite excitations. We introduce a phonon-bitriplon approximation that captures all the physics of hybridization, collective mode formation, and difference-frequency excitation, and show that sum-frequency phenomena also leave clear signatures in the repsonse. We model the appearance of such magnetophononic phenomena in the strongly-coupled spin-chain compound CuGeO$_3$, whose overlapping phonon and spin excitation spectra are well characterized, to deduce the criteria for their possible observation in quantum magnetic materials.

GBs evolve by the nucleation and glide of disconnections, which are dislocations with a step character. In this work, motivated by recent success in predicting GB properties such as the shear coupling factor and mobility from the intrinsic properties of disconnections, we develop a systematic method to calculate the energy barriers for the nucleation and glide of individual disconnection modes under arbitrary driving forces. This method combines tools from bicrystallography to enumerate disconnection modes and the NEB method to calculate their energetics, yielding minimum energy paths and atomistic mechanisms for the nucleation and glide of each disconnection mode. We apply the method to accurately predict shear coupling factors of [001] symmetric tilt grain boundaries in Cu. Particular attention is paid to the boundaries where the classical disconnection nucleation model produces incorrect nucleation barriers. We demonstrate that the method can accurately compute the energy barriers and predict the shear coupling factors for low temperature regime.

A generalised form of time-translation-invariance permits to re-derive the known generic phenomenology of ageing, which arises in many-body systems after a quench from an initially disordered system to a temperature $T\leq T_c$, at or below the critical temperature $T_c$. Generalised time-translation-invariance is obtained, out of equilibrium, from a change of representation of the Lie algebra generators of the dynamical symmetries of scale-invariance and time-translation-invariance. Observable consequences include the algebraic form of the scaling functions for large arguments of the two-time auto-correlators and auto-responses, the equality of the auto-correlation and the auto-response exponents $\lambda_C=\lambda_R$, the cross-over scaling form for an initially magnetised critical system and the explanation of a novel finite-size scaling if the auto-correlator or auto-response converge for large arguments $y=t/s\gg 1$ to a plateau. For global two-time correlators, the time-dependence involving the initial critical slip exponent $\Theta$ is confirmed and is generalised to all temperatures below criticality and to the global two-time response function, and their finite-size scaling is derived as well. This also includes the time-dependence of the squared global order-parameter. The celebrate Janssen-Schaub-Schmittmann scaling relation with the auto-correlation exponent is thereby extended to all temperatures below the critical temperature. A simple criterion on the relevance of non-linear terms in the stochastic equation of motion is derived, taking the dimensionality of couplings into account. Its applicability in a wide class of models is confirmed, for temperatures $T\leq T_c$. Relevance to experiments is also discussed.

We present Crystal Host-Guided Generation (CHGGen), a diffusion-based framework for crystal structure prediction. Unconditional generation with diffusion models demonstrates limited efficacy in identifying symmetric crystals as the unit cell size increases. CHGGen addresses this limitation through conditional generation with the inpainting method, which optimizes a fraction of atomic positions within a predefined and symmetrized host structure. We demonstrate the method on the ZnS-P$_2$S$_5$ and Li-Si chemical systems, where the inpainting method generates a higher fraction of symmetric structures than unconditional generation. The practical significance of CHGGen extends to enabling the structural modification of crystal structures, particularly for systems with partial occupancy, surface absorption and defects. The inpainting method also allows for seamless integration with other generative models, providing a versatile framework for accelerating materials discovery.

We introduce an approach for performing spectrally resolved electron microscopy without the need for an electron spectrometer. The method involves an electron beam prepared as a coherent superposition of multiple paths, one of which passes near a laser-irradiated specimen. These paths are subsequently recombined, and their interference is measured as a function of laser frequency and beam position. Electron--light scattering introduces inelastic components into the interacting path, thereby disturbing the interference pattern. We implement this concept using two masks placed at conjugate image planes. The masks are complementary and act in tandem to fully suppress electron transmission in the absence of a specimen. However, electron interaction with an illuminated specimen perturbs the imaging condition, enabling electron transmission through the system. For a fixed external light intensity, the transmitted electron current is proportional to the strength of the local optical response in the material. The proposed technique does not require monochromatic electron beams, dramatically simplifying the design of spectrally resolved electron microscopes.

Magnetic core/shell nanoparticles are promising candidates for magnetic hyperthermia due to its high AC magnetic heat induction (specific loss power (SLP)). It's widely accepted that magnetic exchange-coupling between core and shell plays the crucial role in enhancing SLP of magnetic core/shell nanoparticles. However, the physical contribution of exchange coupling to SLP has not been systematically investigated, and the underlying mechanism remains unclear. In this study, magnetic hard/soft CoFe$_2$O$_4$/MnFe$_2$O$_4 and inverted soft/hard MnFe$_2$O$_4$/CoFe$_2$O$_4$ core/shell nanoparticles were synthesized, systematically varying the number of shell layers, to investigate the physical contribution of internal bias coupling at the core/shell interface to AC heat induction (SLP). Our results show that a unique magnetic property, double-hysteresis loop, was present and clearly observed, which was never reported in previous core/shell research literature. According to the experimentally and theoretically analyzed results, the double-hysteresis behavior in core/shell nanoparticles was caused by the difference in magnetic anisotropy between core and shell materials, separated by a non-magnetic interface. The enhanced SLP and maximum temperature rise (TAC,max) of core/shell nanoparticles are attributed to the optimized magnetic anisotropy, AC magnetic softness and double hysteresis behavior due to the internal bias coupling. These results demonstrate that the rational design capabilities to separately control the magnetic anisotropy, AC/DC magnetic properties by varying the volume ration between core and shell and by switching hard or soft phase materials between core and shell are effective modalities to enhance the AC heat induction of core/shell nanoparticles for magnetic nanoparticle hyperthermia.

We explore novel topological responses and axion-like phenomena in three-dimensional insulating systems with spacetime-dependent mass terms encoding domain walls. Via a dimensional-reduction approach, we derive a new axion-electromagnetic coupling term involving three axion fields. This term yields a topological current in the bulk and, under specific conditions of the axions, real-space topological defects such as magnetic-like monopoles and hopfions. Moreover, once one the axions acquires a constant value, a nontrivial boundary theory realizes a (2+1)-dimensional analog of the Witten effect, which shows that point-like vortices on the gapped boundary of the system acquire half-integer electric charge. Our findings reveal rich topological structures emerging from multi-axion theories, suggesting new avenues in the study of topological phases and defects.

Disordered stealthy hyperuniform (SHU) packings are an emerging class of exotic amorphous two-phase materials endowed with novel physical properties. Such packings of identical spheres have been created from SHU point patterns via a modified collective-coordinate optimization scheme that includes a soft-core repulsion, besides the standard `stealthy' pair potential. Using the distributions of minimum pair distances and nearest-neighbor distances, we find that when the stealthiness parameter $\chi$ is lower than 0.5, the maximal values of $\phi$, denoted by $\phi_{\max}$, decrease to zero on average as the particle number $N$ increases if there are no soft-core repulsions. By contrast, the inclusion of soft-core repulsions results in very large $\phi_{\max}$ independent of $N$, reaching up to $\phi_{\max}=1.0, 0.86, 0.63$ in the zero-$\chi$ limit and decreasing to $\phi_{\max}=1.0, 0.67, 0.47$ at $\chi=0.45$ for $d=1,2,3$, respectively. We obtain explicit formulas for $\phi_{\max}$ as functions of $\chi$ and $N$ for a given $d$. For $d=2,3$, our soft-core SHU packings for small $\chi$ become configurationally very close to the jammed hard-particle packings created by fast compression algorithms, as measured by the pair statistics. As $\chi$ increases beyond $0.20$, the packings form fewer contacts and linear polymer-like chains. The resulting structure factors $S(k)$ and pair correlation functions $g_2(r)$ reveal that soft-core repulsions significantly alter the short- and intermediate-range correlations in the SHU ground states. We also compute the spectral density $\tilde{\chi}_{_V}(k)$, which can be used to estimate various physical properties (e.g., electromagnetic properties, fluid permeability, and mean survival time) of SHU two-phase dispersions. Our results offer a new route for discovering novel disordered hyperuniform two-phase materials with unprecedentedly high density.

The degradation of the hemi-wicking property of superhydrophilic high-energy surfaces due to contaminant adsorption from the ambient atmosphere is well documented. This degradation compromises the performance of such surfaces, thus affecting their efficacy in real-world applications where hemi-wicking is critical. In this work, the role of surface micro/nanostructure morphology of laser-textured metallic surfaces on superhydrophilicity degradation is studied. We explore intrinsic contact angle variations of superhydrophilic surfaces via adsorption of organics from the surroundings, which brings about the associated changes in surface chemistry. Furthermore, we explore condensation from humid air as a scalable and environment friendly methodology that can reinstate surface superhydrophilicity to a considerable extent (64% recovery of intrinsic wettability after three hours of condensation) due to the efficient removal of physisorbed contaminants from the surface texture features. The present results strengthen the argument that contact-line movement at fine scales can be used for de-pinning and removal of adsorbed organic molecules from contaminated surfaces.

We investigate 1D and 2D cluster states under local decoherence to assess the robustness of their mixed-state subsystem symmetry-protected topological (SSPT) order. By exactly computing fidelity correlators via dimensional reduction of effective statistical mechanics models, we pinpoint the critical error rate for strong-to-weak spontaneous breaking of strong subsystem symmetry. Without resorting to the replica trick, we demonstrate that mixed-state SSPT order remains remarkably robust up to the maximal decoherence rate when noise respects strong subsystem symmetry. Furthermore, we propose that the mixed-state SSPT order can be detected by a constant correction to the area-law scaling of entanglement negativity, termed spurious topological entanglement negativity. This also highlights that topological entanglement negativity, a widely used diagnostic for mixed-state topological order, is generally not invariant under finite-depth quantum channels.

Two distinct measurement schemes have emerged for the new technique of two-dimensional terahertz spectroscopy (2DTS), complicating the literature. Here, we argue that the 'conventional' measurement scheme derived from nuclear magnetic resonance and its optical-frequency analogues should be favored over the 'alternative' measurement scheme implemented in the majority of 2DTS literature. It is shown that the conventional scheme avoids issues such as overlapping nonlinearities and facilitates physical interpretation of spectra, in contrast to the alternative scheme.

Complex spatial patterns in biological systems often arise through self-organization without a central coordination, guided by local interactions and chemical signaling. In this study, we explore how motility-dependent chemical deposition and concentration-sensitive feedback can give rise to fractal-like networks, using a minimal agent-based model. Agents deposit chemicals only while moving, and their future motion is biased by local chemical gradients. This interaction generates a rich variety of self-organized structures resembling those seen in processes like early vasculogenesis and epithelial cell dispersal. We identify a diverse phase diagram governed by the rates of chemical deposition and decay, revealing transitions from uniform distributions to sparse and dense networks, and ultimately to full phase separation. At low chemical decay rates, agents form stable, system-spanning networks; further reduction leads to re-entry into a uniform state. A continuum model capturing the co-evolution of agent density and chemical fields confirms these transitions and reveals how linear stability criteria determine the observed phases. At low chemical concentrations, diffusion dominates and promotes fractal growth, while higher concentrations favor nucleation and compact clustering. These findings unify a range of biological phenomena - such as chemotaxis, tissue remodeling, and self-generated gradient navigation - within a simple, physically grounded framework. Our results also offer insights into designing artificial systems with emergent collective behavior, including robotic swarms or synthetic active matter.

We investigate the scattering of two distinguishable particles with unequal masses and a mutual short-range interaction with the aim of quantifying the impact of a tunneling ``projectile'' particle on the quantum mechanical state of the ``barrier'' particle. We find that the states of the barrier particle after the tunneling or reflection of the projectile are displaced by a finite distance that is given by the derivative of the phase of the transmission or reflection amplitudes multiplied by factors dependent on particles' masses, respectively. We demonstrate these results on a numerical example with a resonant interaction between a projectile and barrier. Our work demonstrates physical implication of the concept of phase time delay in the form of finite displacements of particles that are, in principle, experimentally measurable.

Photonic integrated devices are progressively evolving beyond passive components into fully programmable systems, notably driven by the progress in chalcogenide phase-change materials (PCMs) for non-volatile reconfigurable nanophotonics. However, the stochastic nature of their crystal grain formation results in strong spatial and temporal crystalline inhomogeneities. Here, we propose the concept of spatially-controlled planar Czochralski growth, a novel method for programming the quasi-monocrystalline growth of low-loss Sb2S3 PCM, leveraging the seeded directional and progressive crystallization within confined channels. This guided crystallization method is experimentally shown to circumvent the current limitations of conventional PCM-based nanophotonic devices, including a multilevel non-volatile optical phase-shifter exploiting a silicon nitride-based Mach-Zehnder interferometer, and a programmable metasurface with spectrally reconfigurable bound state in the continuum. Precisely controlling the growth of PCMs to ensure uniform crystalline properties across large areas is the cornerstone for the industrial development of non-volatile reconfigurable photonic integrated circuits.

Josephson junctions (JJs) are the key element of many devices operating at cryogenic temperatures. Development of time-efficient wafer-scale JJ characterization for process optimization and control of JJ fabrication is essential. Such statistical characterization has to rely on room temperature techniques since cryogenic measurements typically used for JJs are too time consuming and unsuitable for wafer-scale characterization. In this work, we show that from room temperature capacitance and current-voltage measurements, with proper data analysis, we can independently obtain useful parameters of the JJs on wafer-scale, like oxide thickness, tunnel coefficient, and interfacial defect densities. Moreover, based on detailed analysis of current vs voltage characteristics, different charge transport mechanisms across the junctions can be distinguished. We exemplary demonstrate the worth of these methods by studying junctions fabricated on 200 mm wafers with an industrially scale-able concept based on subtractive processing using only CMOS compatible tools. From these studies, we find that our subtractive fabrication approach yields junctions with quite homogeneous average oxide thickness across the full wafers, with a spread of less then 3$\,$%. The analysis also revealed a variation of the tunnel coefficient with oxide thickness, pointing to a stoichiometry gradient across the junctions' oxide width. Moreover, we estimated relatively low interfacial defect densities in the range of 70 - 5000$\,$defects/cm$^2$ for our junctions and established that the density increased with decreasing oxide thickness, indicating that the wet etching process applied in the JJs fabrication for oxide thickness control leads to formation of interfacial trap state

Explicit example, where the Hawking temperature of a black hole horizon is compatible with the black hole's R\'enyi entropy thermodynamic description, is constructed. It is shown that for every static, spherically symmetric, vacuum black hole space-time, a corresponding black hole solution can be derived, where the Hawking temperature is identical with the R\'enyi temperature, i.e. the one obtained from the R\'enyi entropy of the black hole via the 1st law of thermodynamics. In order to have this Hawking-R\'enyi type thermodynamic property, the black holes must be surrounded by an anisotropic fluid in the form of a Kiselev metric, where the properties of the fluid are uniquely determined by the mass of the black hole, $M$, and the R\'enyi parameter, {\lambda}. In the simplest Schwarzschild scenario, the system is found to be thermodynamically unstable, and the 3rd law of thermodynamics seems to play the role of a cosmic censor via placing an upper bound on the black hole's mass, by which preventing the black hole from loosing its horizon(s).

Spin defects in semiconductors are widely investigated for various applications in quantum sensing. Conventional host materials such as diamond and hexagonal boron nitride (hBN) provide bulk or low-dimensional platforms for optically addressable spin systems, but often lack the structural properties needed for chemical sensing. Here, we introduce a new class of quantum sensors based on naturally occurring spin defects in boron nitride nanotubes (BNNTs), which combine high surface area with omnidirectional spin control, key features for enhanced sensing performance. First, we present strong evidence that these defects are carbon-related, akin to recently identified centers in hBN, and demonstrate coherent spin control over ensembles embedded within dense, microscale BNNTs networks. Using dynamical decoupling, we enhance spin coherence times by a factor exceeding 300x and implement high-resolution detection of radiofrequency signals. By integrating the BNNT mesh sensor into a microfluidic platform we demonstrate chemical sensing of paramagnetic ions in solution, with detectable concentrations reaching levels nearly 1000 times lower than previously demonstrated using comparable hBN-based systems. This highly porous and flexible architecture positions BNNTs as a powerful new host material for quantum sensing.

We investigate the $\phi^{2n}$ deformations of the O($N$)-symmetric (generalized) free theories with a flat boundary, where $n\geqslant 2$ is an integer. The generalized free theories refer to the $\Box^k$ free scalar theories with a higher-derivative kinetic term, which is related to the multicritical generalizations of the Lifshitz type. We assume that the (generalized) free theories and the deformed theories have boundary conformal symmetry and O($N$) global symmetry. The leading anomalous dimensions of some boundary operators are derived from the bulk multiplet recombination and analyticity constraints. We find that the $\epsilon^{1/2}$ expansion in the $\phi^6$-tricritical version of the special transition extends to other multicritical cases with larger odd integer $n$, and most of the higher derivative cases involve a noninteger power expansion in $\epsilon$. Using the analytic bootstrap, we further verify that the multiplet-recombination results are consistent with boundary crossing symmetry.