Papers

This paper introduces an advanced Computational Analytical Micromechanics (CAM) framework for linear thermoelastic composites (CMs) with periodic microstructures. The approach is based on an exact new Additive General Integral Equation (AGIE), formulated for compactly supported loading conditions, such as body forces and localized thermal effects (for example laser heating). In addition, new general integral equations (GIEs) are established for arbitrary mechanical and thermal loading. A unified iterative scheme is developed for solving the static AGIEs, where the compact support of loading serves as a new fundamental training parameter. At the core of the methodology lies a generalized Representative Volume Element (RVE) concept that extends Hill classical definition of the RVE. Unlike conventional RVEs, this generalized RVE is not fixed geometrically but emerges naturally from the characteristic scale of localized loading, thereby reducing the analysis of an infinite periodic medium to a finite, data-driven domain. This formulation automatically filters out nonrepresentative subsets of effective parameters while eliminating boundary effects, edge artifacts, and finite-size sample dependencies. Furthermore, the AGIE-based CAM framework integrates seamlessly with machine learning (ML) and neural network (NN) architectures, supporting the development of accurate, physics-informed surrogate nonlocal operators.

Thermoelectric generators (TEGs) based on commercially used thermal super-insulating materials can facilitate sustainable and large-scale ambient waste heat recovery while bequeathing an added economic and environmental value to thermal insulations in industry. This requires the optimization of the thermoelectric (TE) properties through electrical functionalization of such materials. Moreover, the associated engineering challenges of assembling TEG modules must be overcome. Herein, we propose using super-insulating Resorcinol-formaldehyde (RF) carbogels for scalable and sustainable TE applications through their electrical functionalization. Using a combination of a pyrolysis process and carbon fibers insertion, we achieved an increment by 12 orders of magnitude in electrical conductivity as well as ZT whilst retaining their intrinsic ultralow thermal conductivity (<50 mW/mK). A TE module in the form of a thermoelectric vacuum insulation panel (TVIP), was then fabricated using only a p-type material, to demonstrate a proof-of-concept self-powered WiFi-based vacuum-failure detection application in confined spaces in automobiles or aeronautics. Finally, by extrapolating the optimized output power and with a CAD-assisted assembly of a large TEG module (1000 cm2), the potential of scalable low-grade waste heat recovery is discussed.

The molecular mechanisms by which organic additives such as saccharin control microstructure in nickel electrodeposition remain inadequately understood, particularly the role of the intense interfacial electric field. This study employs density functional theory (DFT) calculations to elucidate the field dependent adsorption behavior of neutral saccharin and its deprotonated anion (saccharinate) on nickel. By employing the B3LYP functional and implicit solvent models, the field dependent adsorption energetics, frontier orbitals and electrostatic potentials are calculated on a nickel surface. Key findings reveal that while saccharinate dominates in bulk plating baths, its strong solvation shell impedes surface adsorption. In contrast, neutral saccharin exhibits energetically favorable adsorption via sulfonyl oxygen or aromatic $\pi$-face interactions, with specific orientations further stabilized by the interfacial field.This selective adsorption at growth sites rationalizes saccharin's role in inhibiting rapid crystallization, promoting grain refinement, and producing bright, level deposits.The results directly link field-modulated molecular stereochemistry to macroscopic coating properties, providing a mechanistic foundation for the rational design of electroplating additives beyond empirical approaches.

In many ways the solution to the Hedin equations represents an exact solution to the many body problem. However, for most systems of practical interest, the solution to the Hedin equations is rendered nearly numerically intractable because the Hedin equations are of functional derivative form. Integral equations, on the other hand, are much more numerically tractable, than functional derivative equations, as they can often be solved iteratively. In this work we present a systematic set of integral equations (with no functional derivatives) - Hedin approximations I, II, III, IV etc. - whose solutions converge to the solutions of the exact Hedin equations. The Hedin approximations are well suited to iterative numerical solutions (which we also describe). Furthermore Hedin approximation I is just the GW approximation (as such this work may be viewed as a systematic improvement of the GW approximation). We present a systematic study of the Hedin equations for zero dimensional field theory (which, in particular, is a method to enumerate Feynman diagrams for field theories in arbitrary dimensions) and show better and better convergence to the solutions of the Hedin equations for higher and higher Hedin approximations, with Hedin approximations I, II and III being explicitly studied. We, in particular, show that the higher Hedin approximations capture more and and more Feynman diagrams for the self energy. We also show that already Hedin approximation II captures more diagrams than the state of the art diagrammatic vertex corrections approach. Furthermore Hedin approximation III is a near perfect match to the exact solutions of the Hedin equations, at least in the zero dimensional case, and enumerates a large number of Feynman diagrams.

While phonon topology in crystalline solids has been extensively studied, its influence on thermal transport-especially in nanostructures-remains elusive. Here, by combining first-principles-based machine learning potentials with the phonon Boltzmann transport equation and molecular dynamics simulations, we systematically investigate the role of topological surface phonons in the in-plane thermal transport of semiconductor thin films (Si, 4H -SiC, and c-BN). These topological surface phonons, originating from nontrivial acoustic phonon nodal lines, not only serve as key scattering channels for dominant acoustic phonons but also contribute substantially to the overall thermal conductivity. Remarkably, for these thin semiconductor films below 10 nm this contribution can be as large as over 30% of the in-plane thermal conductivity at 300 K, and the largest absolute contribution can reach 82 W/m-K, highlighting their significant role in nanoscale thermal transport in semiconductors. Furthermore, we demonstrate that both temperature and biaxial strain provide effective means to modulate this contribution. Our work establishes a direct link between topological surface phonons and nanoscale thermal transport, offering the first quantitative assessment of their role and paving the way for topology-enabled thermal management in semiconductors.

Real-time time-dependent density functional theory (RT-TDDFT) is a powerful approach for investigating various ultrafast phenomena in materials. However, most existing RT-TDDFT studies rely on adiabatic local or semi-local approximations, which suffer from several shortcomings, including the inability to accurately capture excitonic effects in periodic systems. Combining RT-TDDFT with range-separated hybrid (RSH) functionals has emerged as an effective strategy to overcome these limitations. The RT-TDDFT-RSH implementation for periodic systems requires careful treatment of the Coulomb singularity and choosing proper gauges for the incorporation of external fields. We benchmark two schemes for treating the Coulomb singularity - the truncated Coulomb potential and the auxiliary-function correction - and find that the latter shows better convergence behavior and numerical stability for long-range corrected hybrid functions. Additionally, we assess the impact of gauge choice in simulations using numerical atomic orbitals and show that the recently proposed hybrid gauge incorporating position-dependent phases provides a more accurate description of excitonic absorption than the conventional velocity gauge. Our implementation significantly improves the accuracy of RT-TDDFT-RSH for modeling ultrafast excitonic dynamics in periodic systems.

Water's ability to self-dissociate into H$_3$O$^+$ and OH$^-$ ions is central to acid-base chemistry and bioenergetics. Recent experimental advances have enabled the confinement of water down to the nanometre scale, even to the single-molecule limit, yet how this process is altered at the extreme nanoconfinement remains unclear. Using ab-initio calculations and enhanced-sampling machine-learning potential molecular dynamics, we show that monolayer-confined water exhibits a markedly lower barrier to auto-dissociation than bulk water. Confinement restructures both intramolecular bonding and the intermolecular hydrogen-bond network, while enforcing quasi-2D dipolar correlations that amplify dielectric fluctuations. Our results imply that two-dimensional confined water could act as a superdielectric medium and may exhibit superionic behavior, as observed in recent experiments. These findings reveal confinement as a powerful route to enhanced proton activity, shedding light on geochemical niches, biomolecular environments, and nanofluidic systems where water's chemistry is fundamentally reshaped.

Machine Learning (ML) driven discovery of novel and efficient thermoelectric (TE) materials warrants experimental TE datasets of high volume, diversity, and quality. While the largest publicly available dataset, Starrydata2, has a high data volume, it contains inaccurate data due to the inherent limitations of Large Language Model (LLM)-assisted data curation, ambiguous nomenclature and complex formulas of materials in the literature. Another unaddressed issue is the inclusion of multi-source experimental data, with high standard deviations and without synthesis information. Using half-Heusler (hH) materials as an example, this work is aimed at first highlighting these errors and inconsistencies which cannot be filtered with conventional dataset curation workflows. We then propose a statistical round-robin error-based data filtering method to address these issues, a method that can be applied to filter any other material property. Lastly, a hybrid dataset creation workflow, involving data from Starrydata2 and manual extraction, is proposed and the resulting dataset is analyzed and compared against Starrydata2.

Unambiguously identifying unconventional magnetic orders requires probes directly sensitive to their momentum-dependent spin-split band structures. Here, we employ a Zeeman quantum geometry framework to study magnetotransport at the interface between a magnetic topological insulator and an unconventional magnetic insulator. By choosing the magnetic layer to be insulating, the transport response originates solely from the proximity-induced exchange field, eliminating contributions from itinerant magnetic carriers. We focus on the linear intrinsic gyrotropic magnetic (IGM) response, which decomposes into conduction and displacement current components governed by the Zeeman Berry curvature and Zeeman quantum metric, respectively. We uncover a universal hierarchy in which the transverse displacement IGM response exhibits characteristic even-fold angular harmonics for magnetic orders ranging from $p$- to $i$-wave, while the longitudinal IGM response distinguishes the parity of the magnetic order through robust sign-reversal patterns. In contrast, the conduction IGM component remains largely insensitive to the underlying magnetic symmetry. Consequently, the displacement IGM current emerges as a high-fidelity symmetry fingerprint of unconventional magnetic order. Using realistic parameters for experimentally accessible heterostructures, we demonstrate that these signatures are experimentally measurable, establishing Zeeman quantum geometry as a powerful framework for characterizing unconventional magnetic insulators via gyrotropic transport responses.

Barocaloric (BC) effects at liquid-vapor transitions in hydrofluorocarbons drive most commercial technologies used for heating and cooling in the heating, ventilation and air-conditioning sector. However, these fluids suffer from huge global warming potential and alternative gases are less efficient, toxic or flammable. Solid-solid and solid-liquid BC materials have zero global warming potential and could even improve on current device efficiencies. Whilst solid-liquid BCs typically outperform solid-solid BCs, the latter are advantageous as they avoid leaks and present easier handling and recyclability thus facilitating waste management. Here we confine the solid-liquid BC stearic acid inside the nanopores of a functionalised metal-organic framework (MOF) and demonstrate that the colossal BC properties are retained in a solid-state material. Moreover, the enhanced interactions between the pore surface and the BC material allow a level of active control over the thermal response, as opposed to passive encapsulation. Our results open novel avenues to exploit and tune colossal BC effects in a wide range of combinations of solid-liquid BC materials embedded within functionalized MOFs, without the associated engineering drawbacks.

Using a combination of band representation analysis, inelastic neutron scattering (INS), magneto-Raman spectroscopy measurements, and linear spin wave theory, we establish that the non-coplanar antiferromagnet MnTe$_2$ is a tunable Weyl magnon material, hosting symmetry-protected topological nodal lines in its magnon band structure, protected by the the non-coplanar nature of the antiferromagnetic ordering, that transition into Weyl magnons upon the application of symmetry-breaking perturbations using an external magnetic field. By constructing a spin model that reproduces the observed INS magnon spectra and field-dependence of the Raman $\Gamma$-magnons, we directly probe the topological magnon nodal lines and observe their associated signature of non-trivial topology through the pseudo-spin winding of the scattering intensity in angular scans near the nodal lines. Finally, we discuss the emergence of Weyl magnons in the spectrum through an external magnetic field, and analyze the associated magnon thermal Hall effect allowed by the cubic-symmetry breaking and the associated magnon surface modes, shedding light on future in-field INS and thermal Hall experiments. This work establishes a clear magnonic analog to Weyl electrons, enabling further exploration of topological behavior in bosonic systems and highlighting the interplay between magnetic order and band topology in non-coplanar antiferromagnets.

Water nanoconfinement is known to occur inside material void spaces, such as 2D confinement between surfaces, 1D confinement inside nanotubes, and variable-dimension confinement inside nanoporous materials. In the present work we investigate, through molecular dynamics simulations, the morphologies and self-diffusion coefficient of water channels that are nanoconfined in the void space between adjacent surfaces of nanotube bundles - an existing class of materials. In our simulations, we begin with water filling completely the void space, and then we progressively increase the inter-surface separation, maintaining the water content. We find that, as the inter-surface separation progresses, the dimensionality of the water channel decreases from 2D to 1D, the latter consisting of self-confined water channels along surface grooves. The morphologies and self-diffusion coefficients of these 1D water nanochannels are strongly dependent on the nature of the water-surface interaction and on the diameter of the nanotubes. Interestingly, as we decrease the nanotube diameter from 10 to 5 nm, the self-diffusion coefficients of the 1D channels increase by tenfold for hydrophilic surfaces and by sixfold for hydrophobic surfaces, surpassing, in both cases, the bulk water values. We also investigated the water channels at the interstitial voids of the bulk bundle material, finding 1D water channels that are similar to the surface ones.

We synthezised an AlZnMgCu alloy through mechanical alloying and, using Xray diffraction (XRD), identified the formation of the eta prime phase after 40 hours of grinding. Using reaction-free isoconversion theory, we determined that this phase exhibits two different behaviours depending on the heating rate (beta): the eta prime phase at low beta and the eta phase at high beta.The activation energy values at low beta are consistent with the diffusion energies of copper, zinc and magnesium in aluminium. Significant qualitative and quantitative differences in the thermodynamic barriers (Delta H, Delta G and Delta S) are observed for beta values above or below 20 deg C min minus 1.

Microscale additive manufacturing of reflective copper is becoming increasingly important for microelectronics and microcomputers, due to its excellent electrical and thermal conductivity. Yet, it remains challenging for state-of-the-art commercial metal 3D printers to achieve sub-100-micron manufacturing. Two aspects are sub-optimal using commercial laser powder bed fusion systems with infrared (IR) lasers (wavelength of 1060-1070 nm): (1) IR laser has a low absorption rate for Cu, which is energy-inefficient for manufacturing; (2) short wavelength lasers can potentially offer higher resolution processing due to the diffraction-limited processing. On the other hand, laser sintering or melting typically uses continuous wave (CW) lasers, which may reduce the manufacturing resolution due to a large heat-affected zone. Based on these facts, this study investigates the UV (wavelength of 355 nm) nanosecond (ns) laser sintering of Cu nanoparticles. Different laser processing parameters, as well as different nanoparticle packing densities, are studied. Our results show that a short-wavelength laser can reduce the required energy for sintering with decent morphology, and a densified nanoparticle powder bed favors continuous melting. We further show that sub-20 micron printing can be readily achieved with a UV ns laser. These findings provide new insights into short-wavelength laser-metal nanoparticle interactions, which may pave the way to achieve high-resolution micro and nano-scale additive manufacturing.

We develop a symmetry-adapted multipolar $\mathbf{k}\cdot\mathbf{p}$ theory close to the bulk $\Gamma$ point for time-reversal-symmetric, noncentrosymmetric $C_{3v}$ crystals in the strong atomic spin-orbit-coupling ($jj$-coupling) limit. Using a $j\in\{1/2,3/2,5/2\}$ multiplet basis appropriate for heavy-element p- and d-bands, we systematically construct all symmetry-allowed spin-orbit coupling terms up to fifth order in momentum and generalize the usual spin texture to a total-angular-momentum texture. For $j>1/2$, multipolar spin-orbit coupling qualitatively reshapes Fermi surfaces and makes the topology of Bloch states band dependent. This leads to anisotropic high-$j$ textures that go beyond a single Rashba helix. We classify these textures by their total-angular-momentum vorticity $W_{n}$ for every energy band and identify distinct $|W_{n}|=1,2,5$ phases. We show that their crossovers generate enhanced and nonmonotonic current-induced spin-polarization responses, namely the Edelstein effect, upon tuning the chemical potential. Our results provide a symmetry-based framework for analyzing and predicting multipolar spin-orbit coupling, total-angular-momentum textures, and spintronic responses in heavy-element materials without an inversion center.

Amorphous oxide tunneling barriers, primarily formed from aluminum, represent one of the most widely adopted platforms for superconducting quantum bits (qubits). To overcome challenges associated with defects and sample variance among the tunneling barriers, the methodology of alternating bias assisted annealing (ABAA) was introduced in Pappas et. al[1]. The process of applying alternating bias to the barrier and subsequently aging before use was shown to reduce defects in the barrier. Namely, defects that give rise to two-level systems, coupling to the qubit and expediting decoherence. In this work we replicate an expedited ABAA process through a combination of ab-initio molecular dynamics and machine-learned potentials, illuminating how ABAA effects the energy landscape of the barrier.

The emergence of the orbital degree of freedom in modern orbitronics offers a promising alternative to heavy metals for the efficient control of magnetization. In this context, identifying interfaces that exhibit orbital-momentum locking and an orbital Rashba-Edelstein response to an external electric field is of primary importance. In this work, we experimentally investigate the Co/Al system and extend the study to Co/Pt/Al structures. We show that inserting ultrathin Pt layers between Co and Al can significantly modify the orbital properties, highlighting the critical role of Co/Al orbital bonding in generating orbital polarization. We further model the orbital response of these systems using semi-phenomenological approaches and linear-response theory within the framework of density-functional theory.

Computing spectral functions in large, non-periodic super-moiré systems remains an open problem due to the exceptionally large system size that must be considered. Here, we establish a tensor network methodology that allows computing momentum-resolved spectral functions of non-interacting and interacting super-moiré systems at an atomistic level. Our methodology relies on encoding an exponentially large tight-binding problem as an auxiliary quantum many-body problem, solved with a many-body kernel polynomial tensor network algorithm combined with a quantum Fourier transform tensor network. We demonstrate the method for one and two-dimensional super-moiré systems, including super-moiré with non-uniform strain, interactions treated at the mean-field level, and quasicrystalline super-moiré patterns. Furthermore, we demonstrate that our methodology allows us to compute momentum-resolved spectral functions restricted to selected regions of a super-moiré, enabling direct imaging of position-dependent electronic structure and minigaps in super-moiré systems with non-uniform strain. Our results establish a powerful methodology to compute momentum-resolved spectral functions in exceptionally large super-moiré systems, providing a tool to directly model quantum twisting microscope experiments in twisted van der Waals heterostructures.

Quasicrystals, structures that are ordered yet aperiodic, defy conventional band theory, confining most studies to finite-size real-space numerics. We overcome this limitation with a configuration-space framework that predicts and explains the positions and origins of energy gaps in quasicrystalline potentials. We find that a hierarchy of gaps stems from resonant hybridization between increasingly distant neighboring sites, pinning the integrated density of states below these gaps to specific irrational areas in configuration space. Large-scale simulations of a lowest-band tight-binding model built from localized Wannier functions show excellent agreement with these predictions. By moving beyond finite-size numerics, this study advances the understanding of quasicrystalline potentials, paving the way for new explorations of their quantum properties in the infinite-size limit.

Thin amorphous-CoFeB (a-CFB) is deposited by rf-magnetron sputtering on a self-oxidized Si (100) substrate with different film thicknesses ranging from 0.7 nm to 20 nm. The 5-nm-thick a-CFB film is capped with a W layer for comparison. The surface morphology is investigated by using the atomic force microscopy technique. The low roughness of all the surface of the film indicates uniformity, moderate corrosion resistance, and good structural quality. The X-ray diffraction spectra reveal the amorphous nature of the CFB layer, while the W capping is of mixed phase in the experimental thickness regime. In-plane and out-of-plane hysteresis loops obtained from the vibrating sample magnetometry technique show a transition from an upright S to nearly rectangular shape via a completely inverted profile. A self-sustained tilted magnetic anisotropy is stabilized in a seed-free environment based on the direct substrate-to-magnet interaction. The interface anisotropy is estimated to be 0.06 erg/cm2. The complex anisotropic behavior originates from the interplay between interface anisotropy, conventional shape anisotropy, growth-induced anisotropies, and inhomogeneity-induced anisotropies. In essence, effective anisotropy is responsible for the anomalous hysteresis behavior observed in these films, and this work might provide valuable insights to improve the functionalities of amorphous soft magnetic alloys.

This paper provides a construction and existence proof for a 1-parameter family of chiral unbalanced triply-periodic minimal surfaces of genus 4. We name these {gyrating H'-T surfaces, because they are related to Schoen's H'-T surfaces in a similar way as the Gyroid is to the Primitive surface. Their chirality is manifest in a screw symmetry of order six. The two labyrinthine domains on either side of the surface are not congruent, rather one representing the quartz net (qtz) and the other one the dual of the quartz net (qzd). The family tends to the Scherk saddle tower in one limit and to the doubly periodic Scherk surface in the other. The motivation for the construction was to construct a chiral tunable unbalanced surface family, originally as a template for photonic materials. The numeric construction is based on reverse-engineering of the tubular surface of two suitably chosen dual nets, using the Surface Evolver} to minimize area or curvature variations. The existence is proved using Weierstrass parametrizations defined on the branched torus.

We employ the Dynamical Projective Operatorial Approach (DPOA) to investigate the ultrafast optical excitations of germanium under intense, ultrashort pump pulses. The method has very low resource demand relative to many other available approaches and enables detailed calculation of the residual electron and hole populations induced by the pump pulse. It provides direct access to the energy distribution of excited carriers and to the total energy transferred to the system. By decomposing the response into contributions from different multi-photon resonant processes, we systematically study the dependence of excited-carrier density and absorbed energy on key pump-pulse parameters: duration, amplitude, and photon energy. Our results reveal a complex interplay between these parameters, governed by resonant Rabi-like dynamics and competition between different multi-photon absorption channels. For the studied germanium setup, we find that two-photon processes are generally dominant, while one- and three-photon channels become significant under specific conditions of pump-pulse frequency, duration, and intensity. This comprehensive analysis offers practical insights for optimizing ultrafast optical control in semiconductors by targeting specific multi-photon pathways.

First-principles studies were performed on two Mn-based ferrimagnetic Heusler compounds with L21 and B2 structures, that is, Mn2VZ (Z = Al or Ga). The aim was to investigate their magnetic properties, electronic structures, and spin-resolved longitudinal conductivity at finite temperatures. Density functional theory (DFT) and functional integral theory were used. This approach incorporates transverse spin fluctuations through a disordered local moment method and the coherent potential approximation. In all cases, the calculated theoretical Curie temperatures were lower than the experimental values. Alloys with a B2 structures exhibit higher Curie temperatures compared to compounds with an L21 structures. Calculations of the temperature dependence of the density of states (DOS) indicate that the half-metallic electronic structure collapses owing to the renormalization of transverse spin fluctuations at a finite temperatures. However, the spin-resolved longitudinal conductivities demonstrated an improved spin polarization, particularly for Mn2VGa with an L21 structure. This result contradicts predictions based on the temperature-dependent DOS. The competition between the metallic transitions, which are caused by a modification of the DOS, and scattering coming from spin-disorder explains this phenomenon. Both of these effects are induced by transverse spin fluctuations. Additionally, the results show that half-metallicity, as defined by the DOS or conductivity, is inconsistent at finite temperatures. Finally, the total energy landscape of the paramagnetic state was calculated using the fixed spin moment method to investigate the strength of the longitudinal spin fluctuations. These results suggest that the alloys may exhibit strong longitudinal spin fluctuations.

The foundations of irradiation damage theory were laid in the 1950s and 60s within the framework of chemical reaction kinetics. While helpful to analyze qualitative aspects of irradiation damage, the theory contained gaps that delayed its implementation and applicability as a predictive tool. The advent of computer simulations with atomistic resolution in the 80s and 90s revealed a series of mechanisms that have proved essential to understand key aspects of irradiation damage in crystalline solids. However, we still lack a comprehensive model that can connect atomic-level defect physics with experimental measurements of quantitative features of the irradiated microstructure. In this work, we present a mesoscale model that draws from our improved understanding of irradiation damage processes collected over the last few decades, bridging knowledge gained from our most sophisticated atomistic simulations with defect kinetics taking place over time scales many orders of magnitude larger than atomic interaction times. Importantly, the model contains no adjustable parameters and combines several essential pieces of irradiation damage physics: each playing an irreplaceable role in the context of the full model but of limited utility if considered in isolation. Crucially, we carry out a set of experiments carefully designed to isolate the key irradiation damage variables and facilitate validation. Using tungsten as a model material, we find exceptionally good agreement between our numerical predictions and experimental measurements of defect densities and defect cluster sizes.

Magnetic refrigeration presents an energy-efficient and environmentally benign alternative to traditional vapour-compression cooling technologies. It relies on the magnetocaloric effect, in which the temperature of a magnetic material changes in response to variations in an applied magnetic field. Optimal magnetocaloric materials are characterized by a significant change in magnetic entropy under moderate magnetic field. In this study, we systematically investigated the inter-atomic exchange interactions, magnetic anisotropy energy and magnetocaloric properties of MnX (X = N, P, As, Sb, Bi) using a combination of density functional theory and Monte-Carlo simulations. Additionally, the magneto-optical Kerr and Faraday spectra were computed using the all-electron, fully relativistic, full-potential linearized muffin-tin orbital method. The largest Kerr effect observed in MnBi can be inferred as a combined effect of maximal exchange splitting of Mn 3d states and the large spin-orbit coupling of Bi. To extract site-projected spin and orbital moments, spin-orbit coupling and orbital polarization correction are accounted in the present calculation, which shows good agreement between the moment obtained from the X-ray magnetic circular dichroism sum rule analysis, spin-polarized calculation, and experimental studies. The magnetic transition temperatures predicted through Monte-Carlo simulations were in good agreement with the corresponding experimental values. Our results provide a unified microscopic understanding of magnetocaloric performance and magneto-optical activity in Mn-based pnictides and establish a reliable computational framework for designing next-generation magnetic refrigeration materials.

Crystal structure prediction is a fundamental problem in materials science. We present CrystalFormer-CSP, an efficient framework that unifies data-driven heuristic and physics-driven optimization approaches to predict stable crystal structures for given chemical compositions. The approach combines pretrained generative models for space-group-informed structure generation and a universal machine learning force field for energy minimization. Reinforcement fine-tuning can be employed to further boost the accuracy of the framework. We demonstrate the effectiveness of CrystalFormer-CSP on benchmark problems and showcase its usage via web interface and language model integration.

Strong light-matter coupling enables hybrid states in which photonic and electronic degrees of freedom become correlated even in the ground state. While many-body effects in long-range dispersion interactions are known to reshape electronic properties under such conditions, their impact on quantum-optical observables remains largely unexplored. Here, we address this problem using quantum electrodynamical density-functional theory (QEDFT) combined with the recently developed photon-many-body dispersion (pMBD) functional, which can capture higher-order electron-photon correlations and multi-photon processes. We compute ground-state photonic observables including photon number fluctuations, second-order correlations, and quadrature variances, and find squeezing and super-Poissonian photon statistics emerging from light-matter interactions in the strong coupling regime. Our results demonstrate that capturing the full hierarchy of many-body, electron-photon and multi-photon correlations is essential for a consistent description of quantum-optical properties in strongly coupled molecular systems, establishing QEDFT as a first-principles framework for predicting nonclassical photonic features in the ground state of complex systems.

Material scientists and condensed matter physicists have long been divided on the issue of choosing the conceptual framework for explaining why open-shell transition-metal oxides tend to be insulators, whereas otherwise successful theories such as DFT often predict them to be (false) metals. Strong correlation becomes the recommended medicine. We point out that strong correlation can be mitigated by allowing DFT to lower the energy by breaking structural, magnetic or dipolar symmetries. Such local motifs are observed experimentally by local probes beyond the 'average structure' determined by X-Ray diffraction. Observed broken symmetries can arise from slow fluctuations that persist over the observation time or longer. The surprising fact is that when symmetry breaking motifs are used as input to electronic structure calculations, false metals are converted into real insulators without the recommended medicine of strong correlation. Consistently, DFT calculations that show energy lowering symmetry breaking correct most cases where DFT, even with advanced exchange-correlation functionals, previously missed the correct metal vs insulator designation. Total energy calculations distinguish systems that support energy-lowering symmetry breaking from those that do not. This approach distinguishes between paramagnetic insulating and metallic phases and shows mass enhancement in Mott metals. The reason is that symmetry breaking removes many of the degeneracies that exist in a symmetry-unbroken system, reducing significantly the need for strong correlation. If one chooses to ignore symmetry breaking, the persistent degeneracies often call for strong correlation treatment. Thus, symmetry breaking transforms strong to normal correlation and false metals to true insulators. This view sheds light on the historic controversy between Mott and Slater that still reverberates today.

Antiperovskite nitrides (X3AN) are the structural analogues to perovskite oxides, while their epitaxial growth and electronic properties remain largely unexplored. We report the successful synthesis of Ni3InN thin films on substrates with different lattice constants. First-principles phonon calculations confirm the dynamical stability of cubic phase Ni3InN, providing the basis for epitaxial synthesis. High-resolution scanning transmission electron microscopy reveals coherent (001)-oriented interfaces when Ni3InN is grown on LaAlO3 and SrTiO3, while an unexpected (011)-orientation forms on DyScO3, aligning with surface-energy predictions. Transport measurements highlight a strain-controlled Fermi-liquid behavior, correlated with variations in the Ni-3d bandwidth and hybridization. Band structure calculations reveal a dual character near the Fermi level: a high-mobility Dirac-like band and a Ni-3d manifold that drives strange-metal transport with a reduced slope compared to oxide perovskites. The formal Ni valence (+2/3) places Ni3InN in an overdoped correlated-metal regime, distinguishing from most perovskite oxides. This positions antiperovskite nitrides as a promising platform for investigating overdoped Fermi liquids and strange-metal behavior.

Twistronics, which exploits moire modulation of lattice and electronic structures in twisted bilayers, has emerged as a powerful approach to engineer novel quantum states. Recent efforts have expanded beyond two dimensional van der Waals (vdWs) crystals to more complex, strongly correlated materials, where interfacial moire effects can dominate physical properties. Here we demonstrate a generalizable route to fabricate twisted bilayers of transition metal nitrides with vdWs like interfaces, using freestanding CrN membranes as a model system. Twisted bilayer CrN (tCrN) is realized by employing cubic alkaline earth metal monoxides as sacrificial layers, enabling the assembly of clean, controllable interfaces. Electron ptychography reveals well defined, periodic square moire superlattices in tCrN. For a twist angle of 16.3 degree, we identify a nearly commensurate moire lattice with coincident Cr columns, whereas at 45 degree we uncover localized octagonal quasicrystalline order with clear self-similarity. These results establish a practical platform for twisted TMNs and open avenues to explore moire-induced atomic configurations and emergent correlated phenomena in nitride based heterostructures.