Papers

The photocatalytic production of hydrogen peroxide (H$_2$O$_2$) from water is a promising strategy for solar-to-chemical energy conversion. Herein, we investigate the effect of metal-free heteroatom doping (B, O, P, and S) on the structural, electronic, and photocatalytic properties of graphitic carbon nitride (C$_3$N$_4$) for H$_2$O$_2$ production under simulated solar irradiation. While pristine C$_3$N$_4$ exhibits stacked nanosheets, doping induces disorder, partial exfoliation, and changes in interlayer spacing, confirming successful heteroatom incorporation and modification of the electronic and optical properties. Photocatalytic experiments reveal that H$_2$O$_2$ production strongly depends on the sacrificial agent, pH, and reactive-species scavengers. All doped catalysts show enhanced activity compared to pristine C$_3$N$_4$, with 9.6-, 14.8-, 11.0-, and 16.4-fold increases for B-, P-, O-, and S-doped C$_3$N$_4$, respectively. S-doped C$_3$N$_4$ achieved the highest H$_2$O$_2$ production rate of 3022.1 $\mu$mol h$^{-1}$ g$^{-1}$ and an apparent quantum yield of 8.1%, attributed to improved charge separation and optimized selectivity. Mechanistic studies indicate that oxygen activation mainly follows a two-electron (2e$^{-}$) pathway driven by charge-carrier modulation and reactive oxygen species dynamics, with singlet oxygen and photogenerated holes playing a dominant role. In addition, S-doped C$_3$N$_4$ retained over 95% of its activity after five cycles. These results highlight metal-free heteroatom doping as an effective strategy for sustainable photocatalytic H$_2$O$_2$ generation.

Crystalline rhombohedral multilayer graphene (RMG) has emerged as an ideal platform for studying unconventional superconductivity. Here, we report the observation of superconductivity in moiréless rhombohedral heptalayer graphene (RHG) at zero magnetic field. The superconducting phases emerge at low displacement electric fields (|D| < 0.2 V/nm) and are symmetrically distributed about D = 0, with one robust state exhibiting zero resistance and two weaker superconducting features. Comparisons with rhombohedral pentalayer graphene (RPG) reveal distinct perpendicular magnetic-field responses, and quantum oscillation measurements indicate that superconductivity in RHG arises from a half-metallic normal state. These results highlight the strong dependence of superconductivity on layer number and electronic structure in RMG systems and provide new insights into its microscopic origin.

We investigate the Mpemba effect in a dilute sheared granular gas with a velocity-dependent restitution coefficient. Using kinetic theory based on Grad's moment method, we analyze the relaxation dynamics following a sudden change in the shear rate. We show that, despite having a higher initial temperature, a system starting from an isotropic state can relax faster than a system prepared in a sheared steady state, demonstrating a clear Mpemba effect in the temperature evolution. We further demonstrate the emergence of a viscosity Mpemba effect, characterized by crossings in the relaxation curves of the shear viscosity. Remarkably, multiple crossings arise due to an additional intrinsic timescale introduced by the velocity dependence of the restitution coefficient, providing a minimal kinetic mechanism for multiple Mpemba effects in driven granular gases.

Kerr quasinormal modes near algebraically special frequencies exhibit anomalous behavior, including apparent bifurcation, disappearance, and a nonsmooth connection to the Schwarzschild limit, which has remained puzzling for decades. Tracking poles and zeros of Green-function building blocks across different Riemann sheets, we show that the bifurcation is due to an avoided crossing accompanied by resonant excitation, while the disappearance is due to pole skipping caused by cancellation of a quasinormal-mode pole by a Matsubara-mode zero. This resolves the physical origin of these long-standing anomalies.

A graph-theoretic analysis of the steady-state current noise in master equations under a finite thermodynamic force (affinity) is presented. The incidence matrix twisted by a finite affinity is not orthogonal to the standard cycle space, motivating the introduction of twisted circuit matrices to restore the orthogonality. The resulting twisted-cycle matrix yields an interference-like effect, enabling us to express the signal-to-noise ratio as a quadratic optimization problem in terms of twisted-cycle currents. We apply this framework to a Brownian computation model on a tree-like state-transition diagram with exponential backward branching, finite affinity at each step, and a single reset cycle. In the limit of an infinitely long intended computation path $\ell$, the Fano factor of the reset current undergoes a transition from noiseless to Poissonian behavior at an affinity equal to the logarithm of the number of immediate predecessors $\alpha$. This corresponds to an easy-hard transition in the computational time complexity [K. Okajima, K. Hukushima, arXiv:2512.24728 ], which is not captured by the thermodynamic uncertainty relation. This transition point precisely characterizes the thermodynamic costs of logically irreversible computation: in the absence of affinity, the reset cost scales as $\ln \ell$, whereas reaching the transition point requires a thermodynamic force of order $\ln \alpha$ per step to counteract backward branching.

Ultrafast dynamics of collective excitations in superfluids remains largely unexplored beyond the roton region of the Landau excitation spectrum, despite the importance of such dynamics for understanding nonequilibrium processes in these systems. Here, we employ ultrafast coherent control with sequences of femtosecond pulses to perform spectroscopy of multiple quasiparticles in superfluid helium far from equilibrium. By measuring the time-resolved optical birefringence, we track the nonequilibrium dynamics of quasiparticle pairs associated with rotons, maxons and the Pitaevskii plateau region. The spectral lineshape of the roton peak is explained by an ab initio theoretical analysis of the roton-roton interaction. We also reveal strong energy shifts and short lifetimes of both maxon and Pitaevskii-plateau pairs, as well as an influence of the quasiparticle effective mass on the phase of their coherent response to laser pulses. These results demonstrate the ability to extract previously inaccessible information about collective excitations in a strongly interacting quantum fluid by probing its nonequilibrium dynamics on picosecond and sub-picosecond timescales.

We develop an analytical theory for lattice relaxation in twisted moiré heterobilayers, accounting for lattice mismatch, twist, external biaxial heterostrain, and different elastic constants. Starting from continuum elasticity, we derive the self-consistent equations for the in-plane displacement fields and obtain simple perturbative expressions for the layer-resolved in-plane displacement fields induced by lattice relaxation. We apply our theory to graphene on hBN and representative 2H transition metal dichalcogenide heterobilayers, including MoTe$_2$/WSe$_2$ and WSe$_2$/WS$_2$. Our analytical results agree very well with full numerical solutions over experimentally relevant parameters. We further show that heterobilayers can exhibit a buckling instability near alignment, driven by compressive in-plane strain due to moiré relaxation. Our results provide a simple theoretical framework for incorporating lattice relaxation in realistic moiré heterostructures.

Intrinsic two-dimensional magnets serve as a good platform to explore collective, charge-neutral and low-energy excitations. Distinguishing the crucial role of them in experimental aspect remains a challenge for decades. Here, we study the thermal transport in honeycomb antiferromagnet MnPS$_{3}$ with $T_N$=78 K down to very low temperatures (<0.01$T_N$). At high temperatures (>0.1$T_N$), the field dependence of the thermal Hall conductivity exhibits a linear phonon Hall effect and a peak associated with the spin-flop transition due to a strong spin-lattice coupling, well reproducing the previous report (Phys. Rev. B 110, 165147 (2024)). Notably, below 2 K, we find that the field dependence of the thermal Hall conductivity exhibits sign reversals within the spin-flop phase, at which the field dependence of the longitudinal thermal conductivity also shows multiple valleys. We suggest that these anomalies are caused by the redistribution of Berry curvature in magnon bands, demonstrating the superior performance of the thermal Hall measurements to detect the Berry curvature distributions in magnetic insulators.

Despite similarities between models exhibiting absorbing phase transitions (APTs) and those showing Kardar-Parisi-Zhang (KPZ) growth, the relationship between these universal fluctuations has remained elusive. We numerically study (1+1)-dimensional interfaces of (2+1)-dimensional models showing APTs of directed percolation (DP) and compact directed percolation (CDP) classes with an active boundary, finding a universal crossover from short-time APT-governed fluctuations to long-time KPZ fluctuations. Upon rescaling time and length by the APT correlation time and length, the cumulants of the interface height distributions collapse onto a single scaling function. The fluctuation properties of the discrete Domany-Kinzel model and the continuum stochastic Fisher-Kolmogorov-Petrovsky-Piskunov (sFKPP) equation coincide, indicating that the KPZ growth parameters are determined solely by fundamental properties of the APT. For the CDP sFKPP equation, a dimensionless parameter tunes both the critical interface distribution and the KPZ parameters, with the interface properties of the biased voter model recovered in a limiting case. These results uncover a universal crossover in which KPZ fluctuations emerge from APT fluctuations at long times, linking paradigmatic universality classes of nonequilibrium scale-invariant phenomena.

The impact of point defects on thermal transport in uranium nitride (UN) is investigated using a MLIP combined with Green-Kubo (GK) and normal mode analysis (NMA) methods over 300-1500 K. In pristine UN, temperature-dependent calculations of lattice thermal conductivity reveal that four-phonon scattering is essential yet sufficient to accurately capture high temperature anharmonic phonon transport, as evidenced by close agreement between GK and ShengBTE calculations including three- and four-phonon processes. In defective systems, all types of point defects significantly reduce thermal conductivity at low temperature. Mode-resolved analysis further shows that interstitial defects introduce new phonon states due to a stronger local strain effect. Notably, the uranium interstitial leads to strong defect-phonon scattering over broad phonon spectrum, while the other point defects produce more selective scattering, with even reduced phonon scattering for some acoustic modes. The optical contribution to thermal conductivity remains nearly constant in the presence of IU, but decreases with increasing temperature for pristine and the other defect types. The total thermal conductivity, incorporating electron-phonon coupling and an estimated electronic contribution, yields excellent agreement with experiment in the pristine system, with electronic contributions dominating thermal transport above 600 K. Moreover, with defect-electron contribution introduced through a semiclassical electron-defect scattering model, it is found that (i) the total conductivity degradation follows IU, VU, IN, and VN in descending order, and (ii) electron-phonon coupling becomes negligible in defective systems. These results provide a unified understanding of defect-dependent thermal transport in UN.

We study a class of discrete-time random walks in $\mathbb{R}^d$ whose conditional drift decays polynomially in time and grows polynomially with the distance from the origin to the current position. This class is related to several models of self-interacting random processes. We determine the asymptotic behavior of the walk under the assumption that its increments have moments of order $p$ for some $p>2$. In the linear case, where the drift depends linearly on the current position, we establish a phase transition in the convergence in distribution of the normalized process to Gaussian limits. In the nonlinear case, we identify three distinct regimes separated by a critical line and show that the normalized process exhibits qualitatively different behaviors in each regime, including convergence in distribution to a Gaussian law, convergence to a non-Gaussian limit given by the stationary distribution of a stochastic differential equation, and almost sure localization on a hypersphere.

The higher-order topological insulator is an extended concept of the conventional topological insulator, which obeys the generalization of the standard bulk-boundary correspondence. In our paper, we predict the monolayer d1T-phase transition metal dichalcogenide MoS$_2$ to be a higher-order topological insulator, while also possessing intriguing ferroelectric characteristics. We explicitly demonstrate the nontrivial topological index and reveal the hallmark corner states with quantized fractional charge within the bulk band gap. Second, we show the existence of a nonzero orbital Hall conductivity plateau within the energy gap which is a signature to identify higher-order topology system. Additionally, we investigate the relationship between the ferroelectricity and the orbital Hall conductivity of d1T MoS$_2$ and find that the direction of ferroelectric polarization can modulate the positive and negative values of the orbital Hall conductivity $\sigma_{\rm{OH}}^x$. Our findings provide the theory and material candidate for ferroelectricity tunable orbital Hall effect which is promising to realize the external electric field controllable orbitronics.

The widespread adoption of AI-assisted development in scientific software is not a future concern – it is a present reality. Researchers are already using large language models to write code, generate test cases, and draft documentation, yet this practice remains largely unacknowledged and unguided in formal workflows and published work. This ad hoc, ungoverned use of AI represents a systemic risk to scientific software quality, particularly in safety-relevant modeling and simulation tools subject to strict Software Quality Assurance (SQA), or even Nuclear Quality Assurance Level 1 (NQA-1) standards, for which traceability, independent verification, and documented procedures are paramount. The question facing the scientific software community is, therefore, not whether to permit AI-assisted development, but how to govern it responsibly. This paper proposes guidance for AI-assisted code development in the context of strict software quality assurance. Using TMAP8 – an open-source tritium migration code for fusion energy – as a demonstration platform, we propose a structured framework for AI-assisted verification and validation (V&V) case development. V&V case development represents the ideal proving ground for establishing that governance: because validation cases have known solutions, correctness is objectively measurable, errors are identifiable by design, and the artifacts are fully auditable. The proposed guidance, developed based on practical experience described herein, operates within NQA-1 requirements, preserves human accountability, and establishes the disclosure and review standards that responsible AI-assisted scientific software development demands.

In multivalley conductors the inter-valley relaxation time $\tau_v$ and the inelastic relaxation time $\tau_{in}$ may be significantly longer than the intra-valley momentum relaxation time $\tau$. We show that this separation of time scales has dramatic effects on the I-V characteristics of SNS junctions with a multivalley normal region. We generalize the Larkin-Ovchinnikov equations describing superconducting kinetics to the case of multivalley superconductors. We use this generalization to obtain a kinetic description of multivalley SNS junctions. We find that at constant voltage bias $V$, the current $I(V)$ is nonmonotonic; it exhibits two peaks of similar magnitude $I_\text{max,1} \sim I_\text{max,2}$ at $V_1 \sim \hbar(e\tau_{in})^{-1}$ and $V_2\sim \hbar(e\tau_v)^{-1}$, which may greatly exceed the critical current $I_c(T)$. At constant current bias $I$ we find that in a wide interval, $I_c(T) < I \lesssim I_{\text{jump}}$, the nonlinear resistance of the junction is controlled by the long relaxation times and may be several orders of magnitude smaller than the normal state resistance.

We investigate the interplay between unconventional magnetism and superconductivity in a model of a $p$-wave magnet on a square lattice. Using a self-consistent Bogoliubov-de-Gennes approach, we analyze the pairing amplitudes, competition, and coexistence of spin-singlet $s$-wave and spin-triplet $p$-wave pairings in the presence of a magnetic texture with a helical structure along the $x$ direction that is repeated in the $y$ direction. We find that the magnetic helix selectively stabilizes different pairing symmetries depending on its orientation and strength. In particular, mixed-spin $p_x$-wave pairing is enhanced at intermediate magnetic couplings and equal-spin $p_y$-wave pairing is robust and insensitive to all coupling intensities. When the multiple order parameters are simultaneously considered, we find regimes of coexistence and competition. Increasing the magnetic coupling drives two quantum phase transitions. The first from dominant spin-singlet $s$-wave to mixed-spin triplet $p_x$-wave pairings in a regime of coexistence. The second from spin-singlet $s$-wave and mixed-spin triplet $p$-wave pairings with total spin projection $S_z=0$ to dominant equal-spin triplet $p_y$-wave pairings with $S_z=\pm1$ in a regime of mutually exclusive superconducting phases. Our results demonstrate that $p$-wave magnetic order does not merely diminish spin-singlet $s$-wave superconductivity but can actively promote and stabilize spin-triplet $p$-wave pairing, both intrinsically and in proximity to spin-singlet $s$-wave superconductors. These findings highlight unconventional magnets as promising materials for realizing robust triplet superconductivity.

A deformation of a graphene sheet changes more than the positions of the atoms. In the low-energy Dirac theory it also produces geometric electron-phonon vertices. One of these vertices acts as an emergent phonon gauge field, $\calA_\mu$, which couples to the same Dirac current as the electromagnetic vector potential. This shared current vertex gives a direct route from mechanics to electronics: a moving deformation can generate a transverse electric current, and a deformation pattern with emergent phonon flux can bind electric charge. We show that the coefficient of this mixed electromechanical response is the parity-odd current-current correlator of a massive Dirac cone. For an insulating cone the coefficient is the one-cone Chern-Simons value, while for a doped cone in the local regime it is reduced by the Berry curvature factor $m/|\mu|$. We apply the response to explicit deformations. A traveling flexural wave generates a transverse second-harmonic current; a static ripple mixed with a dynamic phonon generates a transverse current at the drive frequency; and two non-collinear modes can generate charge modulation through the emergent phonon flux. We keep the spin and valley sum explicit, so the paper shows when the one-cone anomaly becomes a charge current in graphene and when it instead appears in a valley, spin, or spin-valley channel. For sublattice-gapped graphene with a valley-odd deformation gauge coupling, the two valleys add rather than cancel. The experimentally sharp signature is a transverse electrical signal at twice the flexural-wave frequency, with a phase fixed by the sign of the sublattice gap and a gate dependence that crosses over from a gap plateau to a $1/|\mu|$ decay. These direction, phase, frequency, and gate-voltage selection rules give clean tests of the anomaly-induced electromechanical channel in deformed graphene.

Conventional derivations of phase boundaries from the Clausius-Clapeyron (CC) relation often employ the constant latent heat approximation to maintain analytical functions for sublimation and boiling curves. To address the complex thermodynamics of the solid-liquid transition, we develop a two-phase analytical model by modifying the CC equation to account for a variable enthalpy of fusion along the melting line. Our framework incorporates recent theoretical and experimental progress showing that the ratio of the isobaric heat capacity to the thermal volume expansion coefficient in the solid state is a material constant correlating with the fusion enthalpy and the specific volumes of coexisting phases during melting. Differentiation of this modified CC relation in the low-pressure regime yields a second-order differential equation dictating the melting curve. By imposing appropriate boundary conditions, physically acceptable approximate parabolic solutions are derived. The parameters of these analytic functions are defined exclusively by fundamental thermophysical properties, including the bulk moduli, thermal expansion coefficients, specific volumes of the coexisting phases, and the isobaric heat capacity of the solid state. Rooted in solid-state anharmonicity, our derivation yields approximate parabolic scaling laws that corroborate a recent universal model derived from the Phonon Theory of Liquids [K. Trachenko, Phys. Rev. E 109, 034122 (2024)], supporting the universal parabolic nature of melting curves from a completely distinct theoretical foundation.

We study an agent-based model of self-propelled particles with a velocity-dependent alignment rule. This interaction is orientation weighted and acts along the line connecting neighboring particles. Tuning the alignment strength produces several distinct collective regimes, including disordered gas-like motion, coherent flocking, jammed high-density states, and densely ordered moving clusters with active-crystal-like behavior. These results show that a simple local alignment rule can generate a broad range of nonequilibrium collective dynamics within a single microscopic model.

Prime numbers arise in several contexts beyond number theory, including statistical mechanics, quantum mechanics, and dynamical systems. However, the mechanisms underlying the irregularities of their sequence and their connections to physical systems remain poorly understood. The present work provides further insight into the search for deterministic fingerprints in the prime sequence. To this end, prime gaps at different separation distances are investigated through an empirical analysis. Based on this analysis, a modified local approximation of the Prime Number Theorem is introduced and analyzed empirically, in which the logarithmic gap estimate is evaluated at a midpoint-corrected argument. From this relation an iterative map is obtained that reproduces the classical asymptotic prime spacing at leading order and satisfies an approximate semigroup property. The residual fluctuations are found to follow Gamma distributions rescaled by the correction terms, with a variance exhibiting an approximate power-law scaling in the prime separation distance.

Stochastic forces are usually postulated or obtained by eliminating environmental degrees of freedom. Here we identify a variational origin: fluctuating endpoint data in Hamilton's principle induce fluctuations of the on-shell action. Hamilton–Jacobi propagation transports this boundary imprint, whose gradient generates an effective Langevin force inherited from boundary-action fluctuations. The resulting force is not freely specifiable: its amplitude is filtered by the Hessian of Hamilton's principal function, yielding multiplicative and state-dependent noise. Homogeneous additive Langevin forcing is recovered only as a Markovian coarse-grained limit.

Reverse annealing initializes a programmable quantum annealer in a chosen classical state, reintroduces quantum fluctuations down to a pause point, and returns to readout; repeated cycles form a configurable dissipative dynamics whose schedule knobs are routinely treated as a temperature. On mixed-frustration 12-qubit Ising instances on two D-Wave generations (Advantage2 and Advantage_system6.4), we measure schedule-driven redistribution of the subsystem readout and calibrate each schedule's effective scales, using exhaustive enumeration of the $2^{12}$ configurations, a locked analysis plan with a prior-knowledge disclosure, and regenerated classical reference families. First, schedule shape redistributes basin occupation: 11 of 20 random instances respond to a single-pause-to-two-pause change (15 of 20 for long-hold; block permutation, FDR-controlled), with shifts up to 38 percentage points and changes of dominant-configuration identity. Second, the single-qubit probe temperature does not transfer to the many-body problem: moment-matched inverse temperatures span 0.63-9.1 against a probe value of 7.22, and pause depth and duration each shift the scale on most instances (19/20 and 15/20). Third, no observation requires more than the tested classical families: with update budgets extended below one sweep per cycle, all 33 (device, instance, schedule) cells are reproduced within the tested family (minimum intersection-union $p=0.76$), and schedule-aware spin-vector Monte Carlo brings the late-window statistics within semiclassical reach. A pre-registered linear predictor fails on held-out instances, and an earlier pilot's two-pause enhancement claim is contradicted (Fisher $p=0.0013$). Reverse-anneal schedules are instance-specific basin-occupation controls whose effective scales must be calibrated per instance and schedule; nothing here licenses a quantum-mechanistic reading.

We obtain an exact solution for a generalized three-chain Ising tube (TCGIT) of length $L$ with toroidal boundary conditions and the most general $C_3$-invariant Hamiltonian on an elementary prism, containing 20 independent coupling constants, including an external magnetic field. Using an $8\times 8$ transfer matrix, we derive the exact partition function of the finite system and obtain the free energy, internal energy, specific heat, magnetization, magnetic susceptibility, and entropy in the thermodynamic limit $L\to\infty$. In the general case, $\lambda_{\max}$ is determined by a quartic equation, whereas in the principal special case with even-spin interactions (PSC) the spectrum simplifies substantially: the characteristic polynomial factorizes, and $\lambda_{\max}$ is given by the root of a quadratic equation. For mirror-symmetric subfamilies, we derive explicit formulas for the pair correlation functions and express the magnetization in terms of the components of the eigenvector associated with $\lambda_{\max}$; in the even-spin case with $h=0$, the magnetization vanishes. Important special cases include the width-three planar model with nearest-neighbor, next-nearest-neighbor, and plaquette interactions, including the entropy limit $S(T\to0^+)=(\ln 2)/3$ for $k\ge 0$ and $S(T\to0^+)=0$ for $k<0$, as well as the width-three planar triangular model with distinct nearest-neighbor couplings, three-spin interactions involving neighboring triangles, and an external field.

Flow in porous media is difficult to address using standard analytical or numerical methods due to its complexity. However, since synthetic representations of porous media are easy to produce and data from physical experiments are becoming more widely available, the problem is well-suited to studies that include machine learning (ML) techniques. We discuss a number of features that can be extracted from such data, and their utility as input variables into a standard ML algorithm. These features include structural measures describing the geometry of the porous media, topological measures describing the connectivity, and network measures obtained by modeling the porous media as simplified pore networks. These features enable the prediction of the permeability of the considered (synthetic) porous materials using ML techniques that also leverage the separately computed exact permeability (ground truth). Comparing results obtained using different input variables helps develop a better understanding of the utility of various measures for predicting permeability based on the porous media structure. We show, in particular, that topological data analysis (TDA) provides a useful set of features that can be easily combined with ML to yield meaningful results.

The theory of thermal fluctuations in crystalline membranes is put under scrutiny. In particular, the two critical regimes of the renormalisation group diagram, which are often left out of the discussion because of their instability in one direction, are examined in details. After studying the proper Goldstone mode counting around each of them, the properties of the fluctuations dominating the large scale spectrum are analysed. This shows that the fixed point P2 is a good candidate to describe the melting of a crystalline membrane. The properties of the melted membrane are then compared to the known properties of fluid membranes. As a byproduct of this analysis, we show that the generation of a fluid membrane by melting a bidimensional crystal allows to formulate its correlation functions without being plagued by the ghosts that inevitably show up in the usual Canham-Helfrich action relying on the Monge parametrisation.

Microsegregation-free microstructures can form by solidifying at velocities beyond the absolute stability limit ($V_{\text{abs}}$), where solute partitioning is suppressed by a stable, planar solid-liquid interface. Producing such microstructures is of considerable practical interest; however, $V_{\text{abs}}$ typically exceeds the ${\sim}1$ m/s growth rates encountered in additive manufacturing (AM). Here we demonstrate the absolute stability limit can be reached in sufficiently concentrated hypoeutectic Al-Ag alloys at growth rates well below the 1~m/s typically encountered in additive manufacturing. Dynamic Transmission Electron Microscopy (DTEM) of rapid solidification front evolution – following laser spot melting of Al-Ag thin films – combined with postmortem microstructural characterization, enables detailed quantitative comparison with both phase-field (PF) simulations and a sharp-interface linear stability analysis that uses a non-equilibrium, velocity-dependent phase diagram extracted from the PF model. The analysis predicts that $V_{\text{abs}}$ follows a trend similar to that of the miscibility gap, first increasing and then decreasing with Ag concentration. Predicted values of $V_{\text{abs}}$ are in good quantitative agreement with PF simulations over the entire hypoeutectic concentration range and with experiments for three concentrated alloys. These results inform the prediction and control of microstructural development in concentrated alloys near the absolute stability limit under AM conditions.

Shape memory alloys like NiTi are at the core of emerging thermal management applications, including elastocaloric refrigeration, thermoelastic harvesting, and latent heat storage. Most of these applications benefit from a small scale due to the accelerated heat exchange, but obtaining precise functional properties of films is challenging. Here we demonstrate that transient grating spectroscopy (TGS) enables characterization of elastic coefficients and thermal diffusivity of a 3 $\mu$m thick epitaxial NiTi film during a thermally induced phase transformation. The in-situ measurement of a complete austenite$\rightarrow$R-phase$\rightarrow$martensite$\rightarrow$austenite temperature cycle reveals that the elastic properties exhibit a crossover of the shear moduli (from $c^\prime < c_{44}$ in austenite to $c^\prime > c_{44}$ in martensite) and that the thermal diffusivity changes by 450 $\%$ between the R-phase and austenite. This dramatic change, together with the absence of hysteresis between the R-phase and austenite, makes NiTi a promising material candidate for thermal switches. The results indicate that the change in thermal diffusivity originates from an anomalous heat capacity of the R-phase. Furthermore, our TGS study provides temperature-dependent thermal and elastic properties required for simulating thermal management microsystems using this material.

An analysis of the IR absorbance for the segmented functional groups of liquid crystal dimers: mesogen and linker, enabled the orientation order to be determined and information about the dipole interactions in the nematic and twist-bend nematic phases to be obtained. The long axis orientational order increases as the temperature decreases in the nematic phase, although much more slowly than for the classical nematics, and then reverses this trend in the twist-bend nematic phase due to the tilt of the molecules. In the nematic phase, the short axis of the molecule performs an isotropic uniform rotation and has a uniaxial alignment. In the twist-bend nematic phase, however, biaxial ordering occurs and grows significantly in accordance with the helical deformation of the director. Changes in the mean absorbance in the twist-bend nematic phase were observed: a decrease for the longitudinal dipole at the nematic-twist-bend nematic phase transition, thus emphasizing the antiparallel axial interaction of the dipoles, while the absorbance of the transverse dipoles remains unchanged up to 340 K, and then the latter become parallelly correlated.

In cuprates, electron doping yields a much lower superconducting $T_c$ than hole doping. For recently discovered nickelate superconductors, the analogous doping strategies become more challenging. Consequently, while hole-doped Ruddlesden-Popper (RP) nickelates have been extensively studied, electron-doped RP nickelates remain rarely explored both experimentally and theoretically. Here we fill this gap by systematically investigating the two-orbital bilayer model for three representative systems: bulk La$_3$Ni$_2$O$_7$ at ambient pressure and 15\,GPa, and a heterostructure La$_3$Ni$_2$O$_7$:La$_3$Al$_2$O$_7$ that provides a feasible experimental route to electron doping. Using first-principle calculations and large-scale dynamical cluster quantum Monte Carlo simulations, we find that electron doping generically enhances $s^\pm$-wave pairing superconductivity (SC) in all three cases, with the heterostructure showing the highest $T_c$ in the underdoped regime. Furthermore, our results suggest an inter-orbital cooperative mechanism that the pairing on the $d_{x^2-y^2}$ orbital, induced by that on the $d_{z^2}$ orbital, plays a vital role in the SC. This work provides the theoretical prediction of enhanced SC in electron-doped RP nickelates and calls for future experimental verification.

Concentrated forces acting at the tip of a two-dimensional wedge give rise to the classical Flamant solution to linear elasticity, whose displacement and strain are singular at the tip of the wedge. Starting from nonlinear elasticity, we prove that the Flamant solution gives the leading order response of a slightly truncated wedge to small boundary displacements or loads. This asymptotic result holds for general hyperelastic energies with super-quadratic growth at infinity; it also holds in the borderline case of quadratic growth at infinity, so long as the tip of the wedge is subjected to small enough displacements or loads. A main point of the proof is to restore compactness to low-energy sequences. We do so by applying a logarithmic change of variables sufficiently far from the tip. To justify this change of variables, we prove a geometric rigidity inequality in $L^p$ for truncated wedge domains with a constant that is uniform in the truncation length. This follows from the bi-Lipschitz invariance of the constant in the $L^p$ Friesecke–James–Müller inequality. Using this change of variables, we derive an asymptotic variational principle characterizing the Flamant solution in the singular limit of an ideal wedge.

We invoke a new mechanism to account for multiple magnetization plateaus observed in rare-earth tetraborides. Using a combination of hybrid and semiclassical Monte Carlo simulations of the Kondo lattice model (KLM) on the Shastry-Sutherland lattice (SSL), we find robust magnetization plateaus at fractions 1/6, 2/9, 1/4, 1/3, 1/2, 2/3 and 3/4 of the saturation magnetization. We find that most of the plateau states are partially Kondo screened and emerge from the field-tuning of a complex three-way competition between the kinetic energy, the Kondo coupling, and the magnetic frustration. Most remarkably, the unusual magneto-transport reported in ErB$_4$ and TmB$_4$ admits an unexpectedly simple explanation within our mechanism. This work not only provides an elegant and simple solution to the long-standing puzzle of metamagnetism and anomalous magnetotransport in RB$_4$, but also introduces a novel mechanism to predict and discover new correlated phases in frustrated Kondo lattices.