Papers

In this work, we develop and study the classical Lanczos algorithm allowing us to define Krylov complexity using the symplectic structure of phase space: Poisson brackets take on the role of the quantum commutators and phase-space integrals furnish the inner product needed to define the Lanczos recursion. We show, using general methods of quantum mechanics in phase space, that the $\hbar \to 0$ limit of the usual quantum mechanical Krylov framework smoothly goes over into the classical one. In theories with well-defined semiclassical limits, we show that classical Krylov complexity accurately approximates quantum complexity at early enough times, and thus is a useful characteristic of early-time chaotic dynamics. We define a Krylov-Ehrenfest time, which quantifies the eventual divergence of classical and quantum complexities, corresponding to a characteristic depth of the Krylov chain, $n\sim n_*(\hbar)$, which in the time domain translates to the well-known scale, $t_*\sim\lambda_K^{-1}\log(1/\hbar)$, in generic chaotic systems. We additionally define microcanonical Krylov complexities, both in the classical and quantum setting, which allows one a fine-grained study of complexity, energy shell by energy shell. We apply this framework to the Lipkin-Meshkov-Glick (LMG) and Feingold-Peres (FP) models, which are collective spin systems known to classicalize in the thermodynamic limit. In particular, while the FP model features spectral chaos for some range of coupling values, the LMG model is known to exhibit early-time saddle-dominated scrambling. Our analysis shows that the instability in LMG is resolved by the microcanonical Krylov complexity, which is controlled by the integrable structure of the Hamiltonian in spectral windows away from the instability, both at early and late times.

We show that driven qubit junctions enable programmable control of physical entropy transport, with entropy conductance governed by quantum dynamics rather than by reservoir parameters alone. By comparing two simple quantum architectures – a driven single-qubit junction and a driven two-qubit junction – we find that the two-qubit junction enhances entropy transfer while requiring substantially lower driving power than its single-qubit counterpart. We further reveal two non-intuitive effects in both junctions: a sizable coherent contribution to the entropy current that emerges only under resonant driving, and negative differential entropy conductance, where increasing the thermal bias suppresses entropy flow into the probe reservoir. These results identify quantum logic architectures as programmable devices for entropy transport and suggest routes toward quantum feedback control, reservoir protection and refrigeration in driven quantum circuits.

The ability to precisely pattern micro- and nano-scale objects on surfaces is important for a range of different applications. For example, colloidal patterning has been used to create plasmonic surfaces, light-emitting diodes or authentication marks, while microbial cell patterning can be applied to screening antibiotic response and cellular interactions over larger populations at the single-cell level. However, we still lack versatile techniques that can pattern a wide range of synthetic and biological objects on a spectrum of different substrate types. Here, we present a robust patterning technique based on the directional freezing of a particle or bacterial suspension over a patterned substrate. Growing ice pushes the desired objects into traps in the substrate, while sweeping away non-trapped ones, leaving behind high-fidelity patterns. We show that this method works for a range of different materials (both synthetic particles and microbial cells), and is unaffected by substrate wettability. Furthermore, patterned bacterial cells retain excellent post-assembly viability, highlighting the gentle nature of the assembly technique. Beyond patterning applications, our results also give insights into processes involving the freezing of particulate suspensions. In particular, we demonstrate the importance of the temperature gradient as a key control which determines how particles interact with freezing fronts. Finally, we highlight a tight analogy between particles interacting with a freezing front and with air-water interfaces, suggesting that results from capillarity may shed light on freezing phenomena.

The paper studies martensitic microstructures in polycrystals, focussing on their compatibility across grain boundaries. After a reduction to the case of a planar grain boundary, the case when the grain boundary separates two constant gradients of zero energy is considered. It is shown that for cubic-to tetragonal transformations such a configuration can occur when the relative grain rotation is not in the cubic group. Then the case when the grain boundary separates two simple laminates of zero energy is considered, it being shown using a computer-assisted symbolic calculation that in the cubic-to-tetragonal case compatibility is only possible for a closed set of measure zero in the manifold of grain boundary normals and relative grain rotations, and that a similar slightly weaker result holds for cubic-to-orthorhombic transformations. The results suggest why higher-order laminates are often observed for such transformations. The Taylor set of deformation gradients is defined and studied, this set having the property that any deformation whose gradient belongs to it corresponds to a zero-energy microstructure for the polycrystal independent of grain geometry and grain rotations. New upper bounds for the Taylor set are proved for cubic-to-tetragonal and cubic-to-orthorhombic transformations, generalizing those of Bhattacharya and Kohn using the geometrically linearized theory. We give a simple proof of a related result of Peigney characterizing the positive diagonal matrices in the quasiconvex hull of the energy wells for cubic-to-tetragonal transformations.

Using two complementary approaches, the instability of bismuth monolayers with an orthorhombic structure with respect to the emergence of spontaneous electric dipole moments at the crystal lattice sites has been studied. The first approach, based on determining the dipole moments of lattice sites through the polarizability of bismuth atoms and taking into account the local Lorentz-Lorenz field, suggests the possibility of the existence of several antiferroelectric and ferroelectric phases in orthorhombic bismuth monolayers. Using the second approach, the vibrational spectrum of a nonpolar symmetric lattice has been analyzed, and two types of soft optical modes corresponding to the ferroelectric and antiferroelectric instabilities of the monolayers have been revealed. The relationship of the Born effective charges to the polarization direction in the ferroelectric phase, as well as their role in the reduction of the frequency of the polar optical phonon, which characterizes the lattice deformation in the ferroelectric phase due to the dipole-dipole interaction, has been shown.

Topological materials, characterized by symmetry-protected nontrivial band structures such as Dirac cones and Weyl nodes, host diverse quantum phenomena, with potential applications in quantum transport, spintronics, and nonlinear optics. Ultrafast pump-probe spectroscopy has emerged as a powerful tool for exploring nonequilibrium dynamics in these systems. Its femtosecond resolution allows charge, spin, orbital, and lattice interactions to be tracked on their intrinsic timescales, thereby revealing key coupling mechanisms in topological phases. This review summarizes progress in ultrafast spectroscopic studies of topological insulators, topological semimetals, and magnetic topological materials. We first discuss the relaxation pathways of photoexcited surface and bulk electronic states, emphasizing electron-phonon scattering, surface-bulk charge transfer, and ultrafast spin conversion. We then examine population inversion in Dirac and Weyl semimetals, spin-polarization dynamics associated with tilted Weyl bands, and the effects of magnetic order on topological states, including coherent phonon and magnon excitations, magnetically driven topological transitions, and terahertz emission. We further review photoinduced topological phase transitions driven by electronic correlations, lattice distortions, and magnetic order under intense optical excitation, highlighting routes toward nonthermal control of quantum phases. Finally, we outline future directions that combine multidimensional ultrafast spectroscopy with temporal, energy, momentum, and spin resolution and advanced theoretical modeling to establish a unified picture of nonequilibrium topological states. This review aims to provide a useful reference for ultrafast studies of topological quantum materials and to advance their applications in high-speed, low-power information processing, spintronics, and quantum technologies.

We take account of the many-body dynamic interactions by including the wave-vector and frequency-dependent exchange and correlations (xc) kernel $f_{xc}(\qv,\omega)$ in the framework of the dielectric theory of the stopping power of crystals for moving charges. The cases of classical and quantum projectiles are considered. We find that (I) the role of the xc effects in slowing of charges in crystalline solids is more pronounced than it is within the jellium model and (II) For velocities below the stopping maximum, inclusion of xc leads to the improvement of the comparison of the theory with experiment over a range of solid targets. On the other hand, in the high-velocity regime, the role of the dynamic xc proves negligible, which does not contradict experiment, and which we substantiate analytically within the jellium model of the target. The input to our theory is the microscopic dielectric matrix $\epsilon_{\Gv \Gv'}(\qv,\omega)$ within the random phase approximation (i.e., with neglect of $f_{xc}$), the calculation of which matrix is implemented in the existing solid-state codes.

We study the formation, dynamics, and disorder robustness of bound states in attractively interacting SU(N) fermions on a one-dimensional ring lattice. Using exact diagonalization in fixed-momentum sectors and Bethe ansatz exact results as a guide, we resolve the many-body spectrum into bands related to the possible partitions of the particles into bound composites, and characterize their internal structure also through density-density and N-body correlations. A pinning quench protocol reveals a transition from dispersive spreading to dynamical localization as the attractive interaction increases relative to the single-particle hopping. We find that the bound state dynamics for one-particle per component occurs as a many-body quantum walk similar to that of a single particle with a re-normalized effective mass. Such a property, that is the quantum version of the shape-preserving motion of classical solitons, can provide the dynamical signature of the fermionic solitary waves. We probe the robustness of the fermionic bound-state dynamics under on-site disorder.

We consider inhomogeneous random graphs in which vertices are assigned i.i.d.\ random weights, pairs of distinct vertices are connected by an edge independently with a probability that is a bi-variate function of the weights of the vertices, and single vertices are connected to themselves by a self-loop independently with a probability that is a uni-variate function of the weight of the vertex. We apply a renormalisation transformation in which vertices are aggregated into groups of equal size according to a greedy algorithm, namely, distinct groups of aggregated vertices are connected by an aggregated edge if and only if there is at least one edge connecting two constituent vertices across the groups, while a group of aggregated vertices is connected to itself by an aggregated self-loop if and only if there is at least one self-loop at an internal vertex or one edge connecting a pair of distinct internal vertices. We analyse what happens when the renormalisation transformation is iterated. In particular, we show that, starting from appropriately scaled connection functions, the iterated renormalised graphs converge to a two-parameter family of random graphs, acting as an attractor in a universality class. We consider a light-tailed regime, for which the scaling limit is a homogeneous Erdős–Rényi random graph, and a heavy-tailed regime, for which the scaling limit is an inhomogeneous random graph with stable infinite-mean random weights and an exponential disconnection function. Different scalings are needed for the two regimes. Which of the two regimes prevails depends on the choice of the connection functions and the choice of the law of the random weights.

Here, we report magnetothermopower measurements on overdoped (Bi,Pb)2(Sr,La)2CuO6+delta (Bi2201) single crystals in magnetic fields up to 35 T. Whereas the temperature dependence of the zero-field Seebeck coefficient S(T) can be captured using Boltzmann transport theory, the field-dependent response S(H) cannot. Instead, the magnetothermopower contains a large additional contribution whose field and temperature dependence is consistent with the presence of short-range superconducting order well above Tc. Combined with earlier Hall and magnetoresistance results, these data imply that the overdoped cuprate strange metal contains two transport sectors with distinct particle-hole symmetry: a conventional particle-hole-asymmetric Fermi-liquid (FL) contribution governing the Hall effect and the zero-field thermopower, and a nearly particle-hole-symmetric sector dominating the anomalous longitudinal magnetotransport. We formulate a phenomenological real-space model in which disconnected FL islands are embedded in a compensated Dirac liquid of phase-incoherent d-wave Bogoliubov quasiparticles. This picture reconciles conventional zero-field transport with anomalous magnetothermopower and magnetoresistance and offers a concrete framework for thinking about strange metallicity in overdoped cuprates.

The quantum Hall effect establishes that topology can fix a material response to integer multiples of fundamental constants when an energy gap isolates the relevant symmetry-protected electronic states. Whether such universal quantization can also emerge in gapless matter, where topological bands coexist with a continuum of metallic excitations, has remained a fundamental question in the field of quantum materials. Chiral topological semimetals provide a unique setting in which to explore this principle; when optical transitions are confined to a single chiral node, the resulting circular photogalvanic effect is predicted to be quantized by the topological charge of the node. In real materials, however, this nonlinear optical phenomenon has remained experimentally elusive, obscured by trivial band transitions, insufficient energy separation between node pairs, and their relative positions with respect to the Fermi level. Here we observe a quantized circular photogalvanic effect in the chiral topological semimetal Rh0.95Ni0.05Si. Band engineering via Ni substitution opens a photon-energy window dominated by interband optical transitions at the {\Gamma}-point multifold node. This allows circularly polarized near- to mid-infrared pulses to drive a helicity-odd terahertz response that manifests three hallmarks of quantization: a sharp onset, a photon-energy-independent plateau governed by the magnitude of the monopole charge, and an abrupt long-wavelength cutoff imposed by Pauli blocking. Our work thus establishes an all-optical analogue of the quantum Hall effect and a new paradigm to realize topological quantization in gapless matter.

Fractionalized Fermi liquids ($\mathrm{FL}^{\!*}$), elusive metallic states characterized by fractionalized quasiparticles alongside conventional ones and defying Luttinger's theorem, are prime candidates for the pseudogap regime of underdoped cuprates. We show that a $\mathrm{FL}^{\!*}$ phase emerges in the single-band $t$-$J$ model through a simple ghost-Gutzwiller Ansatz, optimized at the cost of a mean-field calculation. The resulting temperature-doping phase diagram encompasses a low-doping $\mathrm{FL}^{\!*}$, a $d$-wave superconducting dome, and an overdoped conventional Fermi liquid, thereby reproducing key qualitative features of cuprate phenomenology.

Dynamically processing mechanical signals is crucial for soft robotics and mechanosensing, where classical viscoelastic materials lack intrinsic tunability. We show that internal bistability actively controls the response and signal attenuation in mechanical (meta)materials. In our model, bistable elements switch discretely with a predefined timescale between states distinguished by potential energy $\epsilon$, equilibrium length $\Delta l$, and spring constant $\Delta k$. The system is simulated via microscopic Brownian dynamics coupled to Poisson switching with rate $\nu$, and described macroscopically by a nonlinear continuum field theory. Crucially, the model yields closed-form analytical solutions for the linear response and spatial penetration depth, revealing two phenomena: a universal screening mechanism (akin to the electrostatic 'skin effect') reducing spatial signal penetration when the driving frequency exceeds the internal relaxation rate, and a frequency-insensitive response plateau from timescale separation. The screening length is controlled primarily by the conformational length change $\Delta l$, while the attenuation regime and plateau are tuneable via the switching rate $\nu$. A systematic parameter study exposes a fundamental design trade-off: larger $\Delta l$ strengthens dissipation but raises the energy barrier for state transitions, eventually causing state-locking where damping vanishes. Optimal attenuation thus requires a compromise between pronounced bistability and a surmountable barrier. Due to its analytical tractability, our framework provides explicit design rules for fine-tuning the adaptive response of bistable media. It applies to diverse experimental systems-from biopolymers to synthetic catch bonds and metamaterials-enabling the predictive engineering of intelligent soft matter for frequency-selective signal processing.

We study finite-temperature phase transitions in a Josephson-coupled bilayer superconducting film with compact layer phases under an in-plane magnetic field. At zero temperature, where thermally excited layer vortices are absent, the relative-phase sector undergoes a Pokrovsky–Talapov (PT) commensurate–incommensurate (C–IC) transition from a commensurate Fulde–Ferrell (C/FF) state to an incommensurate Bloch superconducting (IC/Bloch SC) state. At finite temperature, compactness separates two distinct defect mechanisms. The C–IC boundary remains a PT soliton-entry line: interlayer Josephson vortex–antivortex-pair solitons enter with the square-root onset $\rho_{\rm sol}\propto [k_0-k_0^c(T)]^{1/2}$. Thermal melting is instead Berezinskii–Kosterlitz–Thouless (BKT)-like, with correlation exponent $\eta=1/4$ at the boundary, but the active vortex channel changes across the phase diagram. Josephson locking suppresses elementary layer vortices in the C/FF state and selects a same-vorticity layer-pair BKT channel, whereas elementary layer vortices control melting of the IC/Bloch SC state.

The integration of ferroelectric barriers into high-temperature Josephson junctions offers a pathway to tunable superconducting quantum devices. Here, we demonstrate robust Josephson coupling in YBa2Cu3O7-x (YBCO)/Bi0.5Na0.5TiO3 (BNT)/YBCO trilayer junctions incorporating a 40 nm ferroelectric BNT barrier. Epitaxial trilayers were fabricated by pulsed laser deposition on SrTiO3 substrates and investigated under broadband terahertz (THz) irradiation (0.5-2.5 THz). At 1.5 THz, close to the Josephson plasma resonance, the BNT polarization increased from 33.4 to 46.4 uC/cm2 at 30 K, enhancing superconducting transport. The junctions exhibited a well-defined zero-voltage supercurrent branch, with the critical current Ic(T) remaining nearly constant up to 60 K and reaching 468.2 uA under 1.5 THz excitation, evidencing strong phase coherence. Scanning tunneling spectroscopy revealed an enhanced superconducting gap in YBCO/BNT/YBCO (Delta = 1.3 meV) compared with pure YBCO (Delta = 1.05 meV), while optical conductivity measurements showed a reduction in conductivity and gap with increasing temperature, consistent with BCS theory under THz excitation. Atomic force microscopy and X-ray reflectivity confirmed uniform morphology and sharp interfaces, excluding defect-mediated transport. Magnetic field modulation of Ic(B) exhibited a canonical Fraunhofer interference pattern, and resistance mapping revealed alternating lobes of high and low dissipation, indicating coherent Josephson tunneling. These results establish that Josephson coupling is intrinsic to the YBCO/BNT/YBCO junctions, enabled by the dipolar character and dynamic THz response of the BNT barrier. This study identifies BNT as a viable, tunable barrier material for next-generation high-Tc superconducting quantum devices.

We propose a simple method to employ ab-initio calculations to determine magnetic contributions to free energy of alloys. Validation on the Co-Ni binary demonstrates that this ab initio approach reproduces experimental FCC-HCP phase equilibria while providing physically transparent, structure-dependent magnetic parameters suitable for multicomponent extrapolation. Our results demonstrate that physically grounded magnetic parametrization, derived directly from electronic structure calculations, enables predictive phase diagram modeling for magnetic alloy systems.

Measurement-induced phase transitions (MIPTs) in monitored quantum circuits are usually characterized by preparing steady states at different uniform measurement probabilities. Here we introduce a spatial realization of the MIPT by imposing a deterministic measurement gradient in a single monitored Clifford chain. The resulting steady state contains coexisting volume-law, critical, and area-law regions, with the point $p(x)=p_c$ acting as a spatial critical cut. By scanning entanglement observables across this profile, we show that the transition is organized by a spatial scaling form. Although this structure is analogous to finite-time scaling in temporally driven MIPT, the spatial protocol has no Kibble-Zurek dynamics. Instead, the physical bounds $0\le p\le 1$ impose a finite linear window, producing cutoff-controlled asymptotic regimes whose fitted exponents provide direct access to the correlation-length exponent $\nu$. Our results establish spatially inhomogeneous measurements as a controlled route to engineer and probe measurement-induced criticality within a single steady state.

We develop an exact Gaussian-remainder hierarchy for the probability density of the sum of $N$ independent, identically distributed random variables with broad, finite-variance distribution for the summands. The hierarchy separates the Gaussian fixed-point contribution from residual sectors that retain the original single-summand density. For subexponential densities, the first nontrivial truncation yields a simple finite-$N$ approximation that involves one convolution with a Gaussian background and a subtraction that removes Gaussian overcounting. This approximation captures the Gaussian center, the crossover region, and the big-jump tail within a single expression, as demonstrated numerically for stretched-exponential and finite-variance power-law examples. The same first-order approximation reproduces the known asymptotic anomalous rate function for sums of stretched-exponential random variables and also provides an accurate approximation to the corresponding finite-$N$ rate function.

We uncover a family of many-body periodic orbits in a periodically driven (Floquet) spin system away from the high-frequency limit. While linear stability analysis predicts that perturbed many-body trajectories remain close to stable periodic orbits, thermodynamic principles dictate that Floquet heating will ultimately set in. Our work aims to resolve the tension between these two expectations. In particular, we show that perturbations away from the stable periodic orbits feature a description akin to a quasiparticle band structure. A long-lived prethermal regime appears when modes around the gapless point are slowly populated. The dispersion determines the prethermal lifetime, and we show how band engineering leads to a "doubly tunable" parametric dependence of the prethermal lifetime $R^{-W}$, with $R$ the width in momentum space of the quasiparticle distribution and $W$ the exponent of the dispersion around the gapless point. Our results not only establish a powerful route toward stabilizing non-equilibrium phases of matter in driven many-body systems but also establish a conceptual bridge between periodic orbits in 'low-dimensional' nonlinear systems and many-body chaos.

We investigate magnetic domain wall (DW) dynamics in a uniaxial ferromagnetic nanowire under the localized Gaussian temperature profile of a laser spot using the stochastic Landau-Lifshitz-Gilbert equation. The DW velocity increases linearly with peak laser temperature and decreases with increasing laser to DW distance. The velocity varies nonlinearly with Gilbert damping because damping strengthens thermal magnon excitation but shortens the magnon propagation length. The DW initially lies away from the laser-heated region, so the temperature gradient at its position is effectively zero and the entropic torque is negligible. The DW motion is therefore mainly driven by magnonic spin-transfer torque. We analyze laser temperature, laser to DW distance, damping, uniaxial anisotropy, and laser width. The analysis shows that laser width and laser to DW distance independently control the DW response. These findings may clarify the mechanism of localized thermally driven DW motion and guide thermal control strategies in spintronic racetrack-memory devices.

Hyperspectral photoluminescence (PL) of moiré transition-metal dichalcogenide heterobilayers encodes spatially varying exciton landscapes, but extracting that information is hampered by the ambiguity of multi-peak spectral decomposition. Here we develop a peak-decomposition-free inverse framework for quantitative optical metrology of effective disorder coordinates. From the raw cube $I(x,y,E)$ we construct physically motivated descriptor maps – centroid energy, dominant emission energy, spectral width, low/high spectral-weight ratio, and dominant–centroid offset. Their spatial autocorrelation hierarchy and covariance structure form a robust descriptor fingerprint of multi-scale disorder-sensitive spectral statistics. By matching these descriptor summary statistics to a minimal smooth-plus-trap generative model through a grid-Bayesian inverse, we infer effective disorder coordinates $\Thetaeff=\{\Ws,\xis,\Wt,\nt\}$ with explicit uncertainties. Using synthetic PL cubes generated from controlled multi-scale landscapes, we recover the well-identified smooth-disorder coordinates and constrain the trap sector up to a strength–density degeneracy. We report this degeneracy explicitly as an intrinsic identifiability limit rather than a deficiency of the method, and map four canonical disorder regimes onto a disorder-coordinate diagram. The descriptor statistics are stable against shot noise and pixel pitch, and behave predictably under optical-resolution and energy-window changes. The same pipeline ingests experimental cubes without modification, making it directly applicable to two-dimensional and moiré materials. Our results establish descriptor-based hyperspectral PL as a practical, minimal-assumption route to optical disorder diagnostics and provide the validated core of a reusable analysis workflow (HyperPL-Diag) for moiré exciton systems.

We theoretically demonstrate a second-order topological insulating phase induced by compensated altermagnetism, while keeping the bulk gap unchanged, in a two-dimensional topological insulator film. By introducing a layer-resolved out-of-plane $d$-wave altermagnetic term with opposite signs on the top and bottom layers, the system preserves $\mathcal{PT}$ symmetry and maintains spin degeneracy in the bulk bands, while simultaneously gapping the helical edge states and generating localized corner states. The resulting higher-order phase is characterized by nonzero mirror-graded winding numbers, and an effective edge theory shows that the corner states arise from Dirac mass domain walls. We further determine the phase boundaries analytically and construct the corresponding topological phase diagram, establishing a robust route to higher-order topology without bulk spin splitting.

Spin-orbit coupling (SOC) underpins modern spintronics by enabling the electrical generation of spin torques. Its reciprocal counterpart, in which magnetization dynamics produce electromotive forces through a spin-dependent Berry phase, is known as emergent electromagnetic induction (EEMI). However, this effect has previously been observed only in magnetic textures with spatial gradients, such as domain walls, helices, and skyrmions. Here, we demonstrate that even a spatially uniform ferromagnet can host EEMI through a previously unrecognized Berry-phase mechanism inherent to noncentrosymmetric conductors. In the polar Weyl ferromagnet PrAlGe, an applied alternating current generates spin-orbit torques that drive collective magnetization dynamics. The resulting emergent toroidal moment (T = P \times M), where (P) is the crystal's polar axis and (M) is the net magnetization, acts as a gauge potential whose time derivative (dT/dt) induces a Hall voltage. This contribution appears specifically in the out-of-phase component of the AC Hall response and scales linearly with frequency, providing direct evidence for EEMI. First-principles calculations further reveal that this toroidal vector encodes the collective motion of Weyl nodes in momentum space. These findings establish "emergent toroidal induction" as a new manifestation of spin-orbit entanglement, unifying Berry phase, topology, and spin dynamics while opening a pathway toward intrinsic and energy-efficient spin-charge interconversion.

We construct a minimal spinful tight-binding model on a square lattice, where a $d$-wave sublattice-staggered altermagnetism drives the quantum anomalous Hall effect. Here the exchange field is staggered between the two sublattices, where it takes opposite signs on $A$ and $B$ described by the Pauli matrix $\tau_z$. The resulting insulating phases host tunable Chern numbers $\mathcal{C}=\pm1$ and $\mathcal{C}=\pm2$, controlled by the staggered exchange strength and the sublattice-staggered potential. We determine the complete phase diagram, identify valley-resolved band inversions at the $X$ and $Y$ points in the Brillouin zone, and demonstrate chiral edge states together with quantized two-terminal conductance plateaus. Our work provides a simple route to realizing the quantum anomalous Hall effect in compensated magnets via a $d$-wave sublattice-staggered altermagnetism.

We propose an interlayer-engineering scheme to realize a two-dimensional hybrid-order topological insulator, characterized by the coexistence of first-order and second-order topological phases, in a coupled trilayer Chern system. Starting from three quantum anomalous Hall layers with Chern numbers $\mathcal{C}_{1/2/3}=+1/-1/+1$ in the decoupled limit, interlayer tunneling hybridizes their edge states into a single chiral edge mode, while simultaneously opening a gap that supports corner states. Consequently, the system exhibits the coexistence of one-dimensional chiral edge states and zero-dimensional corner states within the same bulk gap, a hallmark of the hybrid-order topology. Furthermore, we map out the topological phase diagram, and show that the hybrid-order phase is robust against mass-type disorder. Our results identify interlayer hybridization as a minimal and broadly applicable strategy for engineering coexisting edge and corner states within a topological platform.

We calculated the potentials of mean force (PMFs) between a ring-like host and a spherical guest in a solvent mixture. We adopted hard-body interactions between particles to discuss the effects of solvent-particle translational motion. The PMFs were obtained using the three-dimensional Ornstein-Zernike equation coupled with the modified hypernetted-chain closure (3D-MHNC-OZ theory). The entropic stabilization at the recognition site is confirmed, and a free-energy barrier wall is observed surrounding it. The free-energy barrier for the solvent mixture is much lower than that for the one-component solvent. Similar barrier reduction for the association of two spherical solute molecules has also been reported, and the mixing effect also reduced the dimerization stability. By contrast, the mixing effect does not significantly reduce recognition stability in the present study. In this respect, the behavior of the host-guest association is different from that of the association of two spherical solute molecules.

The Ce$^{3+}$ pseudospin-1/2 degrees of freedom in the pyrochlore magnets Ce$_2$X$_2$O$_7$, with $X$ = Zr, Hf, or Sn, possess dipole-octupole character. The XYZ nearest-neighbor model Hamiltonians which have successfully described their properties make them attractive candidates for quantum spin ice ground states. We report new heat capacity measurements to very low temperatures on a high-quality single crystal of Ce$_2$Sn$_2$O$_7$ grown by hydrothermal techniques. Our zero-field measurements uncover a clear first order transition to long-ranged order at $T \sim 0.04$ K, well below the downturn in the broader Schottky-like anomaly that is a common feature in the zero-field heat capacity for cerium pyrochlores. This observation settles the debate as to whether Ce$_2$Sn$_2$O$_7$ possesses a QSI ground state in zero field - it does not. However, we also find compelling evidence suggesting that spin ice physics is nearby, and remains relevant to Ce$_2$Sn$_2$O$_7$. Application of a magnetic field along the $[1,1,0]$ direction leads to an evolution of this peak to a weak anomaly at higher temperature more characteristic of a continuous, mean field transition. At higher fields along $[1,1,0]$, the Schottky-like anomaly bifurcates similar to expectations for independent polarized $\alpha$ and orthogonal $\beta$ chains in classical spin ice. These new experimental results demonstrate richness to the phase diagram for Ce-based pyrochlores.

Magnetic refrigeration in the sub-Kelvin regime requires refrigerant materials to retain a large magnetic entropy at low temperatures by suppressing magnetic ordering. Quantum spin liquids (QSLs), which evade long-range magnetic ordering while retaining strong quantum fluctuations to the lowest temperatures, therefore provide a promising platform for realizing high-performance magnetic refrigerants. Here, we investigate the magnetic ground state and the magnetocaloric effect of the hexaaluminate, NdMgAl$_{11}$O$_{19}$, in which the Nd$^{3+}$ ions form a network of triangular lattices. Magnetic susceptibility and specific heat measurements indicate a magnetically dynamic state down to 50~mK, consistent with a QSL state. Specific heat measurements further reveal substantial magnetic entropy retained below 50~mK. Quasi-adiabatic demagnetization measurements demonstrate a superior cooling performance of NdMgAl$_{11}$O$_{19}$, which can be cooled to 113~mK from 1.9~K by only a small magnetic field change of 2~T. The outstanding refrigeration performance is attributed to the persistent spin fluctuations associated with the QSL-like ground state, together with a large effective g factor and the smallness of the exchange interactions along the easy-axis direction. This study demonstrates that frustration, combined with strong spin-orbit coupling and crystal-electric-field effect in the rare earth magnets provides a promising design principle for next-generation cryogenic magnetic refrigerants.

Multiple CDW-ordered layered rare-earth tellurides have increasingly emerged as a research hotspot, owing to their unconventional CDW formation, high transition temperature, and confirmed existence of axial Higgs modes. Recently, interweaved CDW in LaTe2 and its element-substituted phase LaTe2-xSbx have been investigated through TEM and ARPES measurements, revealing their distinct origins. Nevertheless, several complex diffraction features observed in TEM patterns remain unelucidated. In this work, we carried out scanning tunneling microscopy (STM) on LaTe1.6Sb0.4 crystals at 9 K. Three interweaved CDW wave vectors, q1=8/11a*, q2=5/11a* and q3=3/11a* were observed, which are induced by hole doping in unoccupied states. The q1 and q3 are theoretically verified to be nesting vectors connecting px- and py- bands. Furthermore, the satellite spots relative to the main Bragg spots p corresponding to a 11-a-superlattice have also been detected. Our findings provide critical insights for further exploring the origin of the interweaved CDW in hole/electron doping materials.

We propose a route for encoding a helicoidally twisted synthetic geometry in mesoscopic quantum circuits. A torsionless spatial metric with twist parameter $\Om$ defines an electrostatic capacitance kernel whose angular–axial sector contains the chiral coupling $-2\Om mk$. We show that this kernel can be implemented by a finite, quantizable circuit graph built only from positive two-node capacitors: diagonal bridges generate the cross term, and the dimensionless twist is the ratio of diagonal to total angular capacitance. The resulting capacitance matrix enters the Hamiltonian through $C^{-1}(\etaT)$ and splits counter-rotating synthetic modes. Exact finite-graph diagonalization confirms the analytic spectrum and shows that closed longitudinal circulation is required; with open boundaries the bridge phase is gauge removable and the doublets remain degenerate. Simulated spectroscopy resolves the chiral fan, while disorder simulations indicate that calibrated percent-level reactive disorder does not obscure the deterministic splitting in the parameter range considered. Twist textures produce interface modes, Josephson nonlinearities make the Kerr sector chirality dependent, and the same doublet provides a detuning knob for non-Hermitian exceptional-point control. For representative circuit-QED parameters the splitting is in the tens-of-MHz range, well above typical resonator linewidths.