Papers

A liquid drop falling into a deep pool can create a vortex ring at the right impact conditions. Such drop-formed vortex rings are of importance in nature and technology and the dynamics of rings created by single and synchronised double drop impacts have been extensively studied. In practice, two neighbouring drops rarely impact a liquid surface exactly at the same time, yet the interaction of two unsynchronised vortex rings have not been studied. Here, we have performed experiments with two water drops impacting a water pool at varying time differences $\Delta t$. By using particle image velocimetry, we have quantified the time-evolution of the resulting vortex rings. We find four distinct categories of vortex ring evolution depending on $\Delta t$. At $\Delta t<0.5$ ms, fully symmetric merging of the vortex rings occur. An unsynchronisation larger than this drastically influences the collision and merging, which either becomes asymmetric and incomplete ($0.5 < \Delta t<7$ ms) or does not happen at all ($\Delta t \geq 7$ ms). At $7 \leq \Delta t<80$ ms, the creation of the second vortex ring is impaired, whereas at $\Delta t\geq 80$ ms, the first impact no longer affects the formation of the second ring and eventually the two rings evolve without influencing each other. We show that these different regimes can be explained by the capillary waves created by the first droplet. Our results demonstrate the importance of the time difference between drop impacts in the creation and subsequent interaction of two adjacent drop-formed vortex rings, which is important for achieving uniform and controlled mixing in high-throughput applications.

A metallic point contact formed on a non-superconducting or weakly superconducting material often nucleates or enhances superconductivity confined under the contact. However, no unified theoretical description of the phenomenon exists. We show that the spatially inhomogeneous, predominantly uniaxial nature of the stress field under a point contact is fundamental for such tip-induced and tip-enhanced superconductivity (TISC/TESC). We also show that the coupling of such a stress field to the electronic structure can be estimated through an experimentally measurable uniaxial coupling scale $C^{\mathrm{exp}}$. Combining Hertzian contact mechanics with a Ginzburg-Landau variational analysis, we derive a criterion for the nucleation of TISC/TESC and determine $C^{\mathrm{exp}}$ for twenty-one materials. For topological semimetals with ungapped band crossings, the framework explains observed critical temperatures with no free parameters and for all others, $C^{\mathrm{exp}}$ provides a direct experimental determination of the uniaxial strain sensitivity and a target scale for microscopic theories.The work predicts TISC in elemental Sb and Y with $T_c \approx 2.8$\,K and $T_c \approx 12$\,K respectively.

We investigate the effects of quantum fluctuations (QFs) and finite-range interatomic interactions on the ground state and wall tension of a Bose-Einstein condensate (BEC) at zero temperature by means of modified Gross-Pitaevskii equations. The QFs are shown to stiffen the condensate near the hard wall, narrowing the density profile and raising the wall tension above its mean-field value by an amount proportional to square-root of the gas parameter. Finite-range corrections always reduces the wall tension relative to the QFs correction value regardless of the effective range. We find the ordering $\gamma_0 < \gamma_{\rm II} < \gamma_{\rm I}$ in the dilute regime and identify a crossover condition under which the two beyond-mean-field contributions mutually cancel. These results provide an experimentally accessible way for probing beyond-LHY physics through precision measurements of the wall tension in ultracold Bose gases.

Quantum materials exhibit exotic phases and electronic responses under irradiation by circularly polarized light, which breaks time-reversal symmetry and generates Floquet replica bands. Recently, Floquet topological states arising from direct resonances have attracted much attention, e.g., the emergence of Floquet-Weyl points at a one-photon resonance, rather than topological features within the modulated original bands via high-frequency expansion. In this study, we investigate the effects of a one-photon resonance in a representative three-dimensional topological insulator, Bi$_2$Se$_3$, applying Floquet theory under circularly polarized light. We find that four pairs of Floquet-Weyl points emerge in the intermediate-frequency regime, mediated by hybridization between the original and one-photon-resonant Floquet bands, preserving the threefold rotational symmetry of the crystalline structure. Our numerical calculations demonstrate that tuning the chemical potential via hole doping yields a large anomalous Hall conductivity, directly associated with these Floquet-Weyl points. This work provides a highly accessible route toward the experimental realization of one-photon-resonant Floquet-Weyl semimetals.

We study the emergence of superconductivity in a quantum spin Hall insulator and identify a disorder-driven enhancement of pairing arising from quantum geometry. Using sign-problem-free quantum Monte Carlo simulations of the attractive Bernevig-Hughes-Zhang (BHZ) Hubbard model, we obtain a quantum phase transition as a function of interaction strength for different impurity densities. In the clean limit, the system develops bulk superconductivity for Hubbard interaction $\vert U \vert$ above a finite critical strength. Interestingly, strong impurities significantly reduce such $\vert U \vert$ required for the onset of superconductivity. Our calculations indicate that Cooper pairing first nucleates in subgap ring states surrounding the impurities and then evolves into a globally coherent superconducting phase. Our results demonstrate that impurity-generated bound states can promote superconductivity in systems with strong quantum geometry. This mechanism is expected to be relevant in nearly flat-band systems like moiré materials where quantum geometry plays a dominant role.

Surface reconstructions induced by atomic adsorption can strongly reshape metallic surface states, providing a direct pathway to tune their electronic structure. Using angle-resolved photoemission spectroscopy, we investigate the electronic structure of Sb/Au(111) during the coverage-driven evolution from the clean Au(111) surface to the $(14\times14)$ and Rec$(3\times\sqrt{3})$ phases. In the Rec$(3\times\sqrt{3})$ phase, triangular Fermi pockets emerge at the Brillouin-zone boundary. Their momentum positions are consistent with a reciprocal-space folding construction, but their reduced size near the Fermi level indicates a modification of the Au-derived $sp$ dispersion. The substantial modifications of deeper Au $d$-derived bands observed in ARPES further indicate significant mixing between Sb $p$ orbitals and Au $d$ states. These results show that the electronic structure of Sb/Au(111) is governed by the interplay between reconstruction-induced Umklapp scattering and interfacial orbital hybridization, highlighting adsorbate-substrate hybridization as a key mechanism for tuning and engineering surface electronic structures.

Bose-Einstein-condensed (BEC) and superfluid dark-matter (SFDM) halos can contain coherent, wave-supported cores whose angular momentum is carried by quantized vortices. When vortices form a tangle, reconnections convert part of the vortex kinetic energy into dark phonons, density waves, Kelvin waves, and vortex loops, providing a microscopic channel by which vortex structure can affect halo-core evolution. We estimate the dynamical importance of this channel by combining the local Gross-Pitaevskii (GP) reconnection law with a halo-scale vortex-line density calibrated against Schrödinger-Poisson (SP) simulations. Vortex reconnections cannot appreciably restructure a standard SP halo core under the fiducial assumptions: for a $m=10^{-22}$ eV, $r_c=1$ kpc soliton and a one-percent energy-transfer efficiency per event, an unforced network transfers at most $1.3\%$ of the core virial energy in 10 Gyr. Reconnection converts ordered vortex energy into sound and smaller-scale excitations; we bound the cumulative transfer using a spectral scale measured in published SP halo simulations. To connect the result with measured systems, we match the standard soliton profile to half-light masses derived with a single mass estimator for eight classical Milky Way dwarf spheroidals. Assigning the measured aperture mass to the soliton gives ceilings of $0.98-4.52\%$ at the Mocz line-density reference and $0.061-3.19\%$ for a modest-rotation normalization. The largest value is a factor of 22 below the core virial-energy scale and limits the fixed-structure velocity change to $2.3\%$. The spectral reference represents fewer than one projected vortex crossing, so these are continuum upper limits; a vortex-free core has no reconnection heating. Reconnections remain worth testing because they are unavoidable when a tangle exists.

Understanding how nonequilibrium driving modifies phase-separation kinetics remains a fundamental challenge. Here we show that phase separation in a two-temperature system exhibits a striking density-induced reentrant coarsening behavior. Using Brownian dynamics simulations and a coarse-grained field-theoretic model, we find that the characteristic domain size grows as $L(t)\sim t^{1/z}$, displaying a reentrant sequence $(t^{1/3} \rightarrow t^{1/4}\rightarrow t^{1/3})$ with increasing density. While the low- and high-density regimes are governed by classical curvature-driven bulk diffusion, the intermediate-density regime exhibits anomalously slow growth. We show that this slowdown originates from a transport bottleneck arising from the interplay of particle diffusivity, particle availability, and attachment kinetics, which suppresses the effective mass flux between domains. Unlike equilibrium phase separation, where density primarily affects morphology and crossover scales, the two-temperature drive renders density a key control parameter for coarsening pathways. Our results uncover a nonequilibrium mechanism for anomalous domain growth in two-temperature systems.

Tissue surfaces exhibit complex curvature during embryogenesis and oncogenesis. Evidence shows that cells can actively sense curvature to regulate behavior and fate, yet the underlying mechanism remains unclear. Here, we develop a vertex model for arbitrary curved surfaces and uncover spontaneous cell size patterning on ellipsoidal surfaces: cells in high-curvature regions are consistently larger than those in low-curvature regions. This non-uniformity arises from a mechanical competition encoded in Riemannian geometry: positive Gaussian curvature reduces the perimeter-to-area ratio of polygonal cells, relaxing cell-edge tension in high-curvature regions, which is compensated by area expansion to maintain global force balance. This area pattern is robust against variations in model parameters and matches observations in biological systems. The perimeter pattern, in contrast, is governed by competition between the intrinsic geometric tendency and the deformation required by force balance, and undergoes reversal beyond a critical shape index. Together, these findings establish self-organized spatial variations in cell size as a potential physical mechanism for curvature sensing.

This work systematically unveils the nanoscale surface damage dynamics in gallium nitride by investigating the atomistic mechanisms of hillock formation. The results identify two distinct hillock morphologies dependent on electronic energy loss (Se) values. Bell-shaped hillocks form under 18.2 keV/nm Kr irradiation, whereas crater-rim hillocks with central holes emerge under 40.2 keV/nm Ta irradiation. Microstructural analysis reveals that Ga-rich hillocks are accompanied by the generation of metastable zincblende nanodomains. These nanodomains preferentially aggregate around the periphery or sidewalls of the hillocks and exhibit a high spatial correlation with screw dislocations. Further temperature-dependent studies indicate that elevated temperatures significantly enlarge the overall dimensions of the hillock structures without altering their fundamental morphologies. Notably, under Ta irradiation above 1200 K, the high temperatures drastically reduce the viscosity and surface tension of liquid gallium. This enhanced fluidity of the transient molten phase promotes the formation of penetrating nanochannels.

Hybrid nanomaterials incorporating deep eutectic solvents (DES) in porous hosts or at solid interfaces are gaining increasing attention for their potential interest across a wide range of applications. Under these conditions, the performances of DESs may be influenced by interfacial effects and spatial restrictions. In this study, we examined the effects of nanoconfinement on both the structure and molecular dynamics of the prototypical DES ethaline (a mixture of choline chloride and ethylene glycol) when confined within the cylindrical mesopores of SBA-15 (Dp $\approx$ 8.1 nm) and MCM-41 (Dp $\approx$ 3.5 nm) silicas, using neutron diffraction and quasielastic neutron scattering. It demonstrates that ethaline remains structurally homogeneous under confinement, showing no evidence of core-shell segregation within the pore cross-section. The molecular dynamics of the confined ethaline preserve the key characteristics observed in its bulk state. Translational diffusion follows a jump-diffusion mechanism, with diffusion coefficients that remain remarkably close to the bulk values, showing only a modest reduction in MCM-41. A more pronounced increase in the residence time t0 between translational molecular jumps is observed. It corresponds to roughly a factor of 3-8 under confinement in SBA-15, and reaches up to a tenfold enhancement in MCM-41 relative to bulk. Similarly, the characteristic relaxation time, tL, associated with the localized in-cage motion of ethaline, increases by approximately 20% in SBA-15 and up to 50% in MCM-41. However, the molecular trajectories, modeled from the elastic incoherent structure factor, remain largely preserved under confinement, showing only a marginal reduction in intra-basin motional amplitudes.

Revealing the mechanisms of phonon scattering is crucial for understanding material properties such as transport characteristics and optical responses. It can be discussed by measuring the temperature dependence of the phonon energy and lifetime. To gain insight into these mechanisms in Weyl semimetal T$_d$-WTe$_2$, we investigated coherent phonons using time-resolved pump-probe spectroscopy in a wide temperature range from 4.6 to 300 K. The temperature dependence of the frequency and decay rate of the two high-frequency optical modes was described by the conventional anharmonic phonon-phonon scattering model. In contrast, the low-frequency mode at 2.4 THz exhibited anomalous behavior, which can be interpreted as the contribution of phonon-electron scattering.

High refractive index dielectrics are central to photonic applications, yet the empirical Moss rule imposes a fundamental trade-off between refractive index and optical transparency. We introduce a modified Moss rule anchored to the optical absorption edge rather than the fundamental bandgap, capturing materials where various physical mechanisms suppress absorption well above the electronic gap. Screening the Materials Project database with this metric reveals recurring chemical compositions and structural prototypes in the materials with the most promising refractive index/transparency trade-offs. These materials include chalcopyrites, Zintl pnictides, and early transition metal multi-anion chalconitrides and oxychalcogenides compounds. Hybrid density functional theory calculations reveal that the chalconitride (Hf,Zr)2(S,Se)N2 family can achieve a combination of ultra-high refractive indices, low effective masses and transparency windows extending deep into the UV, surpassing state-of-the-art TiO2 and SiC. Our results establish (Hf,Zr)2(S,Se)N2 compounds as a unique and largely unexplored material family for next-generation photonic applications.

The substitutional alloy SrTi$_{1-x}$V$_x$O$_3$ interpolates between the band insulator SrTiO$_3$ and the correlated metal SrVO$_3$, exhibiting a composition-driven metal–insulator transition whose origin combines Mott physics with local chemical disorder. Previous first-principles studies relied on individual supercells, which cannot capture the thermally disordered solid solution, since configurations of identical composition can display very different electronic properties. Here we treat the alloy within a generalized quasi-chemical approximation, a thermodynamically consistent statistical framework in which every property is obtained as an ensemble average over all symmetry-inequivalent clusters, weighted by occurrence probabilities that minimize the Gibbs mixing free energy. This provides a well-defined procedure to average over different supercells, and places the structural and electronic descriptions on an equal footing. From the mixing thermodynamics we obtain a miscibility gap with a critical temperature of 1443 K, consistent with experimental evidence. Combining the cluster ensemble with dynamical mean-field theory, we track the density of states at the Fermi level across the full composition range: whereas density-functional theory alone predicts a metal for all $x>0$, the correlated spectral function reproduces the transition, evolving from insulating below $x\approx0.3$ to metallic near $x=1$. Finally, classifying clusters as metallic or insulating and performing site percolation on a simple cubic lattice yields a sharp onset of system-spanning conduction near $x\approx0.4$. These results establish a thermodynamically consistent, configuration–averaged framework applicable to the broader class of correlated materials.

Three-dimensional magnetic solitons retain topological protection only while their spin field remains continuous. Here we show that chemical inhomogeneity can break this protection in a controlled way, converting a hopfion-like toroidal texture into an effectively two-dimensional skyrmion string. Tilt-dependent Lorentz transmission electron microscopy, electron energy-loss spectroscopy, and micromagnetic simulations of pristine, uniformly Y-doped, and nonuniformly Y-doped disordered TiO2 nanoparticles embedded in a FeCrNiMn host reveal two regimes. Uniform Y doping enriches Ti3+/oxygen-vacancy localization centers and stabilizes closed rings with Hopf invariant QH approximately 1. Nonuniform Y doping forms a Ti4+-rich, vacancy-depleted boundary that creates a sharp q=D/(2A) gradient and a weak-moment leakage channel. This coupled mismatch torque and continuity leakage split the ring, leaving a skyrmion-string remnant and a field-sensitive helicity texture.

This article follows up on arxiv:2511.15938, in which we developed an Hamiltonian renormalization scheme to construct a quantized theory of Fermi liquids. Here, we apply this formalism to a low-temperature atomic Fermi gas where the short-range interactions are fully parametrized by the s-wave scattering length $a$. We benchmark our renormalized theory by recovering known perturbative results on the static properties of the Fermi gas, such as the Lee-Huang-Yang expansion of the equation of state, the Galitskii expansion of the momentum distribution, and the Gor'kov-Melik Barkhudarov preexponential correction to the critical temperature. We then turn to the transport dynamics and demonstrate the presence of a preexponential correction to the speed of zero sound when including corrections of second order in $a$. Finally, we develop an efficient numerical method to solve the transport equation exactly, and we apply it to study the crossover from the collisionless to the hydrodynamic regime in the density and polarisation response functions.

Density functional theory struggles to accurately determine electron density of atoms, whose error is inevitably encoded into the pseudopotential and propagated into solid-state calculations. However, little is known about how this affects accuracy nor how to remedy it. In this work, through a systematic study of the effect of Cu atomic density on bandgap and lattice constants of over 50 Cu-containing simple closed-shell semiconductors, we find that core-electron density can drastically affect nuclear attraction to valence electrons and subsequent charge distribution and energy position of Cu 3$d$ electrons. The error can be eliminated at its source by employing modified Hartree-Fock pseudopotentials for Cu core while retaining (semi-)local functionals for valence electrons. This real-space partitioning approach leads to simultaneous high-accuracy in bandgap and lattice constants across the entire material class.

Due to their enhanced resistance to coarsening and/or creep, aluminium alloys with precipitates of two distinct phases in a core-shell morphology are of great contemporary interest. In this paper, we focus on the curious observation in two recent studies on Al-Sc-Li and Al-Yb-Li alloys that growth of the shell phase leads to a narrowing of the size distribution. We have studied this phenomenon, known as size focusing, using a theoretical framework (which extends Zener's theory of diffusional growth to a core-shell precipitate) and multi-precipitate simulations based on a phase field model. Our results yield key theoretical insights as well as conclusions with practical significance. (a) On the theoretical front, we show clearly that size focusing is a growth phenomenon: it ends when shell growth ends, and coarsening begins. (b) On the practical front, our results offer guidelines for designing alloys with narrower size distributions: size focusing is promoted in alloys with greater shell volume fractions and greater inter-precipitate spacing.

Bulk 1T-TaSe$_2$ is metallic, yet its surface consistently exhibits an insulating gap – a dichotomy long attributed to a surface Mott insulator driven by enhanced electron correlations. Using density functional theory calculations, we show that this insulating surface instead originates from a charge-density-wave (CDW) stacking reconstruction. Whereas the bulk stabilizes a single-layer CDW stacking that supports metallic transport, the surface energetically favors a bilayer stacking, in which interlayer hybridization of Ta $5d_{z^2}$ orbitals opens a $\sim$0.4 eV gap – a band insulator requiring no on-site Coulomb repulsion. This reconstruction is the thermodynamic ground state for slab thicknesses from two to eight layers, and the calculated surface density of states quantitatively reproduces scanning tunneling spectra of both insulating and metallic domains. CDW surface reconstruction, rather than Mott physics, thus governs the surface electronic structure of 1T-TaSe$_2$, providing a unified explanation for the observed coexistence of metallic and insulating domains.

Machine-learning interatomic potentials (MLIPs) bridge the accuracy of first-principles calculations and the efficiency required for large-scale molecular dynamics (MD) simulations. However, existing MLIP software remains fragmented across different model architectures, making it difficult to establish unified workflows that support flexible model development, efficient training, and scalable MD deployment. Here, we present AI2Pot, a scalable and unified MLIP framework that seamlessly integrates model training, evaluation, and large-scale MD simulations with PyTorch-compatible ecosystem. Instead of relying on generic automatic differentiation for expensive atomistic operators, AI2Pot re-engineers the core computations of Moment tensor potential (MTP) and Neuroevolution potential (NEP) for both training and inference using hand-crafted C++/CUDA code. These specialized operators constitute a unified computational backend shared by training and inference, improving training-inference consistency and reducing memory usage by avoiding large intermediate caches. As a result, AI2Pot enables fast inference for large-scale atomic systems containing millions of atoms on a single GPU, while retaining the flexibility of PyTorch for model construction, training, and evaluation. Trained models can be deployed in ASE and LAMMPS for MD simulations. Furthermore, AI2Pot provides a companion command-line toolkit (AI2Pot-cli) and Python APIs to facilitate practical MLIP workflows. By unifying high-performance atomistic computing with modern machine-learning ecosystems, AI2Pot offers an user-friendly end-to-end framework for the developing, training, and deploying MLIPs for large scale MD.

We theoretically investigate the anomalous Hall and Nernst effects (AHE and ANE) in a two dimensional Kagome lattice to uncover the distinct roles of static and fluctuating scalar spin chi ralities. Employing Monte Carlo simulations incorporating with a tight binding Hamiltonian via the s-d exchange interaction, we explicitly evaluate the anomalous transport coefficients. A key finding is the systematic disentanglement of the macroscopic responses into an intrinsic contribu tion, governed by momentum space Berry curvature induced by static chirality, and an extrinsic skew scattering contribution driven by real space dynamical spin fluctuations. We demonstrate a pronounced mechanistic crossover: deep in magnetically ordered phases like the skyrmion crystal, the intrinsic Berry curvature dictates the transport behavior. However, approaching the magnetic order-disorder critical regime, strong thermal fluctuations disrupt static noncoplanar spin configu rations, drastically suppressing intrinsic responses. Here, dynamical chiral fluctuations emerge as the dominant driving force. By delineating the phase regimes governed by static versus fluctuating chiralities, this work elucidates the distinct microscopic mechanisms dictating anomalous transport in frustrated magnetic systems.

Molecular dynamics is used to study radiation cascades in solid C60 under ambient conditions. Simulations are performed for Primary Knock-On Atom (PKA) energies from 0.1 to 1 keV, and cascades are sampled over many PKA directions to collect statistics. Energies and forces are described using the Environment Dependent Interaction Potential for carbon paired with the Ziegler-Biersack-Littmark potential for short-range interactions, and cascade behaviour is characterized by tracking kinetic energy, hybridization and bond connectivity as a function of time. Compared to most materials, fullerite exhibits an unusual radiation response due to weak thermal transfer between C60 molecules leading to a thermalization phase lasting hundreds of picoseconds. The cascades damage the C60 molecules and link them together, and a linear relation is found between the number of cross-linked molecules and the number of new sp3 atoms. The threshold displacement energy computed is 18 eV, in agreement with experiments

We study invariant measures for soliton systems described by Mealy automata. Motivated by recently introduced soliton models associated with 2-letter, 3-state Mealy automata, we formulate the time evolution induced by Mealy automata on bi-infinite configuration spaces. We provide sufficient conditions for the invariance of Bernoulli product measures and derive a criterion for the invariance of two-sided space-homogeneous Markov distributions. We then apply these general results to three soliton models, which can be interpreted as variants of the box-ball system (BBS). For two of these models, BBS-S(2) and BBS-V(2), we prove that Bernoulli product measures are invariant. For the remaining model, BBS-C(2), we establish a more general result: the invariance of two-sided space-homogeneous Markov distributions, which include Bernoulli product measures as a special case. Furthermore, for all three models, we compute the phase shift associated with the interaction of two solitons, as well as the velocity of an isolated soliton. Although the latter has already been studied previously, both quantities constitute fundamental characteristics for understanding the generalized hydrodynamics of these systems. These results provide a foundation for the study of invariant measures, generalized Gibbs ensembles, and generalized hydrodynamic behavior in Mealy-automaton soliton systems.

Direct, real-space imaging of spin-wave propagation and wavefronts in magnetic materials is crucial for advancing both fundamental understanding of spin dynamics and the development of functional devices. This, however, remains a significant challenge, especially in materials with complex magnetic characteristics at the nanoscale. Here, we employ scanning nitrogen-vacancy center spectroscopy to achieve visualization of spin waves in two archetypical magnetic films: yttrium-iron-garnet and lanthanum strontium manganese oxide. We reveal a wavelength-dependent spin-wave filtering effect near point-like magnetic scatterers and a modified spin wavefront in antiferromagnetically coupled stripe domains. The spin-wave characteristics are explained using micromagnetic simulations and analytical calculations. These findings point to possible fine control of spin-wave propagation near complex magnetic structures and extend the scope of spin-wave imaging based on nitrogen-vacancy centers beyond uniform magnets.

We show that anyonic exchange statistics can activate non-Hermitian point-gap topology in models that are topologically trivial in its absence. The emergent topology oscillates more rapidly with the statistical phase as the anyon number increases, and exhibits a parity dependence on the particle number. A perturbative analysis reveals the mechanism: fractional statistics induces a mismatch between momentum terms that, combined with sublattice-dependent dissipation, produces particle-number-dependent non-reciprocity and complex spectral winding. As these effects rely on the formation and exchange of interaction-bound anyons, our results establish exchange statistics as a resource for enabling non-Hermitian topology under programmed dissipation.

Negative linear compressibility (NLC) is the counterintuitive phenomenon in which a crystallographic axis expands under hydrostatic pressure. A related phenomenon, zero linear compressibility (ZLC), occurs when an axis shows no length change under pressure. Both responses are rare and arise in materials with highly anisotropic mechanical properties. Motivated by recent reports of anomalous behavior in metal cyanides - including negative thermal expansion and NLC - we use first-principles calculations to investigate the potential of the MCN family (M = Ag, Au, Cu) to exhibit ZLC or NLC. Our simulations reveal three main findings. First, we predict the existence of previously unreported phases: the P6mm phase for AgCN and CuCN, and the R3m phase for AuCN. Second, all six members of the MCN family studied exhibit extreme elastic anisotropy, which indeed leads to ZLC or NLC in each case. Third, we identify a mechanism for these responses distinct from previously reported ones. The mechanism arises from the unique "bamboo forest" geometry of the material: weakly interacting rigid rods whose sparse packing allows pressure to be accommodated through changes in packing density rather than rod compression. This mechanism enables the anomalous response to persist over a wide pressure range, contrasting favorably with other materials that exhibit similar behavior. Our findings expand the relatively small family of materials known to exhibit ZLC or NLC and provide deeper insight into the microscopic origin of these unusual mechanical responses.

Fluid injection into the earth's crust can induce small and frequent earthquakes in the subsurface. Predicting their sizes and temporal occurrences via statistical analysis is crucial for safe operations in unconventional oil and gas recovery, enhanced geothermal systems, and geologic carbon storage. Here we show that a simple micromechanical model of slip avalanches in slowly deforming solids predicts the slip statistics observed over drastically different spatial scales, namely meter-scale microseismic observations and nanometer- to micrometer-scale nanoindentation experiments can be described with this model. Microseismic catalogs extracted from high-pressure fluid injection operations into geological basins with various lithologies and nanoindentation experiments on shale across a wide range of temperatures and mineral compositions yield statistics consistent with model predictions. This universality across materials, temperatures, and scales is consistent with the prediction that the slip statistics result from only a few basic properties. Previously debated deviations of the statistics in layered sedimentary formations are explained by finite-size and stress-integrative effects resulting from mechanically weak bedding planes. The slip statistics therefore provide important information about the structure and scales of the bedding planes. Conversely, the basin structure can also be used to predict the probability distribution for the sizes of triggered microseismic events.

Using a Green's-function formalism, we study the spin-resolved local spectral function of a resonant impurity coupled to a two-dimensional $d$% -wave altermagnetic substrate. It is found that the interplay between direct tunneling from the impurity to the scanning tunneling microscopy (STM) tip and altermagnet-mediated tunneling gives rise to a dual Fano resonance in the absence of an external magnetic field. Moreover, the anisotropic spin-dependent oscillations of the local density of states and the corresponding Fano factors provide information on the altermagnetic splitting strength from complementary local and global perspectives. In addition, spin-selective tunneling can be achieved by tuning the Fermi energy and the tip position. In the presence of a strong magnetic field with Landau-level quantization, the dominant scanning tunneling spectroscopy (STS) signature appears as a spin-dependent nodal structure in real space: the nodal mismatch between opposite spin channels produces a large local spin contrast. These results establish resonant-impurity STM/STS as a phase-sensitive local probe of altermagnetic band anisotropy.

We investigate the thermoelectric and magnetic properties of Si-substituted $n$-type and Ti-substituted $p$-type Heusler alloy Fe$_2$VAl using the bipolar random Anderson model, which has been introduced recently to study antisite-defect effects associated with the sign change of the Seebeck coefficient in thermally quenched Fe$_2$VAl. Based on the electronic states of both $n$-type and $p$-type compounds, with the rigid-band shift of the Fermi energy and a temperature-dependent scattering rate taken into account, we elucidate how antisite defects simultaneously influence thermoelectric transport and local magnetic moments. We find that the magnetic moments are enhanced in $n$-type Fe$_2$VAl, whereas they are suppressed in $p$-type Fe$_2$VAl compared with the undoped compound. These contrasting magnetic responses highlight the impact of antisite spin polarization on thermoelectric properties and demonstrate the crucial role of antisite defects in realizing magneto-thermoelectric functionalities in Heusler-type alloys.

We consider observables $X$ whose realizations in a sampled dataset are restricted, for example by measurement resolution, to a finite set of distinguishable categories within their possibly infinite theoretical domain. Given the probabilities of observable categories, we study the coarse-grained probability mass of families of possible datasets generated through a forward sampling process. The combinatorial construction induces an intrinsically discrete $p$-value defined directly from the sampling process rather than through additional probabilistic structure on observables. Specifying the sample means of $d+k$ arbitrary functions $g_\alpha(X)$ defines a linear family of datasets whose probability mass is obtained as a weighted sum over integer lattice points contained within the associated polyhedron. To overcome the intractable large-$N$ combinatorics, we derive via saddle-point techniques a density approximating these probability masses in the continuum limit of forward sampling within the multinomial universality class. As a demonstration, we consider conditional sampling, where $d$ structural means are fixed while $k$ means vary over admissible datasets. The information geometry emerging from the saddle-point density, together with the spherical symmetry arising at large $N$ from the intrinsic $p$-value construction, enables efficient computation of the $p$-value in the Laplace approximation via the $\chi^2_k$ distribution. The resulting statistic is given by the semi-analytic expression $2N$ times the Kullback-Leibler divergence between the information projections associated with the corresponding structural and observed linear families. These projections can be computed efficiently via standard numerical routines converging for sufficiently well-behaved sample means.