Higher-order topological insulators have been widely explored in classical wave systems, characterized by topological states localized at hinges or corners. Conventional approaches to realizing higher-order corner states necessitate bulk materials, which typically result in inefficient use of the bulk. Here we introduce topological vertex states in three-dimensional hollow pyramid structures, achieved by tailoring and folding planar phononic crystals. These vertex states are highly localized at the vertices of hollow pyramid structures formed by the connection of capsule-shaped acoustic cavities. The frequencies of these vertex states can be precisely tuned by deforming the pyramid geometry or integrating external tubes. Interestingly, the pyramids support anomalous acoustic wave partitions of hinge states that do not follow the original planar valley-selective transport rule, stemming from the emergence of projected two-dimensional topologically nontrivial valley configurations of distorted lattices. Notably, the partition ratio can be effectively tuned by the vertex states. Our approach provides an efficient alternative for wave localization and manipulation, reducing bulk material usage while enabling the design of lightweight and compact detectors for advanced sensing applications.

Altermagnets are an emerging class of collinear magnets with momentum-dependent spin splitting and zero net magnetization. These materials can be broadly classified into two categories based on the behavior of spin splitting at time-reversal-related momenta: even-parity and odd-parity altermagnets. While even-parity altermagnets have been thoroughly investigated both theoretically and experimentally, the systems capable of hosting odd-parity altermagnetism remain largely unexplored. In this work, we demonstrate that circularly polarized light dynamically converts collinear $\mathcal{PT}$-symmetric antiferromagnets on dimerized lattices into odd-parity $p$-wave altermagnets. Because of the underlying Dirac band structure of the dimerized lattice, we find that the resulting $p$-wave altermagnets can realize Chern insulators (2D) and Weyl semimetals (3D) under appropriate drive conditions. Our findings demonstrate that collinear antiferromagnets on dimerized lattices provide ideal platforms to investigate the dynamical generation of odd-parity altermagnetism.

We report direct, simultaneous measurements of the London penetration depth (${\lambda }_L$) and Bardeen-Cooper-Schrieffer coherence length (${\xi }_0$) in oxygen-doped niobium, with impurity concentrations spanning the “clean” to “dirty” limits. Two depth-resolved techniques—low-energy muon spin spectroscopy and secondary-ion mass spectrometry—were used to quantify the element's Meissner screening profiles, analyzed within a framework that accounts for nonlocal electrodynamics. The analysis indicates intrinsic length scales of ${\lambda }_L=29.1\left(10\right)\mathrm{nm}$ and ${\xi }_0=39.9\left(25\right)\mathrm{nm}$, corresponding to a Ginzburg-Landau parameter $\kappa =0.70\left(5\right)$. The obtained ${\lambda }_L$ and $\kappa$ values, accurately quantified at the nanoscale, are smaller than those commonly used in applications and modeling, and indicate that clean niobium lies at the boundary between type-I and type-II superconductivity, supporting the contemporary view that its intrinsic state may be type I.

Density functional theory (DFT) in its practical implementations maps a system of interacting electrons onto an auxiliary noninteracting one and is presumably inaccurate for strongly correlated materials. We present a concrete benchmark for DFT by examining the electronic ground state phase diagram of a strongly interacting chain with uneven, noninteger nuclear charges. The interplay between charge imbalance and Coulomb repulsion yields two competing phases, a band insulator and a Mott insulator. By including infinitesimal lattice distortions, DFT stabilizes the intermediate spontaneously dimerized insulator phase that results from this competition. We assess the phase diagram by mapping the bond length and nuclear charge ratio of the chain to the ionic Hubbard model and performing highly accurate density matrix renormalization group calculations. Our comparative study provides foundational insight into the utility of symmetry-broken DFT as a predictive tool for elucidating phase diagrams with competing orders.

For over 30 years it has been known that overdoped cuprate superconductors display a rapid fall in superfluid density (SFD) with increasing doping $p$ along with the decline in $T_c$. This unconventional behavior suggests a depletion of the condensate either by increasing pairbreaking or the growth of a second nonpairing channel. One widely accepted suggestion is that the entire $T_{\text{c}}\left(p\right)$ phase curve is governed by phase fluctuations arising from an already low SFD. More recently, it was proposed that the condensate arises in an incoherent charge channel that progressively gives way with overdoping to a second, coherent nonpairing channel. Here, we examine the electronic specific heat, and its field dependence, of a number of canonical cuprates and find that there is no apparent loss of SFD with overdoping. The SFD per ${\mathrm{CuO}}_2$ plaquette is found to rise progressively from $p$ on the underdoped side towards $(1+p)$ on the overdoped side, much the same as the Hall number. This would imply that all available carriers contribute to the condensate. If so, this could be the underlying intrinsic behavior for all generic cuprates. Our specific heat samples include (Y,Ca)${\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }, {\mathrm{YBa}}_2{\mathrm{Cu}}_4{\mathrm{O}}_8, {\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{CaCu}}_2{\mathrm{O}}_{8+\delta }, {\mathrm{La}}_{2-x}{\mathrm{Sr}}_x{\mathrm{CuO}}_4, {\mathrm{Tl}}_{0.5}{\mathrm{Pb}}_{0.5}{\mathrm{Sr}}_2{\mathrm{Ca}}_{1-x}{\mathrm{Y}}_x{\mathrm{Cu}}_2{\mathrm{O}}_7$, and ${\mathrm{Tl}}_2{\mathrm{Ba}}_2{\mathrm{CuO}}_6$, with the latter being the only clear exception. The question arises as to why. Notably, any nongeneric behavior seems to be confined to the region beyond critical doping where the pseudogap closes.

Optical control offers a compelling route for tailoring material properties on an ultrafast time scale. Ordered states such as charge density waves (CDWs) can be transiently melted by an ultrafast light excitation. This is also the case for the rare-earth tritelluride ${\mathrm{LaTe}}_3$, a prototypical CDW compound. For this material it has recently been reported that the suppression of the primary CDW allows the transient formation of a second CDW, whose wave vector is orthogonal to the primary one. This creates the intriguing scenario where light enables switching between two distinct ordered phases of the material. While the second CDW has so far been observed by structural techniques, it remains an open question how the interplay of the two CDW phases is reflected in the material's electronic structure. We investigate this via time- and angle-resolved photoemission measurements of ${\mathrm{LaTe}}_3$. The complex Fermi contour is probed using a FeSuMa analyzer, which records the photoemission intensity of the entire Fermi contour at once. The dynamics revealed by the FeSuMa analyzer are complemented by measurements using a conventional hemispherical electron analyzer. We combine conventional data analysis with $k$-means clustering, an unsupervised machine learning technique, demonstrating its strong potential for disentangling large datasets. While we do not find any features that cannot be explained by the melting and reestablishment of the primary CDW, distinct dynamics and coherent oscillations are observed in the different branches of the Fermi contour.

Chiral anomaly is a key feature of Lorentz-invariant quantum field theories: in the presence of parallel external electric and magnetic fields, the number of massless Weyl fermions of a given chirality is not conserved. In condensed matter, emergent chiral fermions in Weyl semimetals exhibit the same anomaly, directly tied to the topological charge of the Weyl node, ensuring a quantized anomaly coefficient. However, many condensed matter systems break Lorentz symmetry while retaining topological nodes, raising the question of how chiral anomaly manifests in such settings. In this work, we investigate this question in spin-1 fermionic systems and show that the conventional anomaly equation is modified by an additional nontopological contribution, leading to a nonquantized anomaly coefficient. This surprising result arises because spin-1 fermions can be decomposed into two-flavor Weyl fermions coupled to a Lorentz-breaking, momentum-dependent non-Abelian background potential. The interplay between this potential and external electromagnetic fields generates the extra term in the anomaly equation. Our framework naturally generalizes to other Lorentz-breaking systems beyond the spin-1 case.

Copper-based chalcopyrite semiconductors have attracted sustained interest owing to their promising thermoelectric (TE) performance, yet the microscopic origins of their TE behavior remain incompletely understood. Here, we systematically investigate the TE properties of $\mathrm{Cu}M{X}_2$ ($M=\mathrm{Al}$, Ga, and In; $X=\mathrm{S}$, Se, and Te) using first-principles calculations. Electronic transport is computed from explicit electron–phonon coupling based on the Perdew-Burke-Ernzerhof (PBE) functional-calculated band structures including spin–orbit coupling (SOC), with band gaps and dielectric constants corrected using the screened hybrid functional Heyd-Scuseria-Ernzerhof (HSE06). Lattice thermal conductivities (${\kappa }_{\mathrm{L}}$) are obtained by solving the phonon Boltzmann transport equation with three- and four-phonon scattering rates, using temperature-renormalized second-order force constants from 300 to 800 K. For $p$-type doping, at a fixed temperature and hole concentration, as $X$ varies from S to Te, the hole mobility ($\mu$) increases markedly due to progressively weaker polar optical phonon (POP) scattering, reflecting the reduced ionic contribution to the dielectric response in compounds with heavier chalcogens. Combined with smaller transport effective masses, $\mathrm{Cu}M{\mathrm{Te}}_2$ compounds therefore exhibit high electrical conductivities ($\sigma$) and large power factors (PFs). Across the $\mathrm{Cu}M{X}_2$ family, the anomalously lower ${\kappa }_{\mathrm{L}}$ of $\mathrm{Cu}M{\mathrm{Se}}_2$ relative to $\mathrm{Cu}M{\mathrm{Te}}_2$ arises primarily from enhanced three-phonon scattering at low-frequency regions. For a given $M$, $\mathrm{Cu}M{\mathrm{S}}_2$ displays the steepest temperature-induced decrease in ${\kappa }_{\mathrm{L}}$ and attains a smaller ${\kappa }_{\mathrm{L}}$ than $\mathrm{Cu}M{\mathrm{Se}}_2$ and $\mathrm{Cu}M{\mathrm{Te}}_2$ at 800 K. Given the low band degeneracy and comparatively modest hole mobilities of $\mathrm{Cu}M{X}_2$ compounds, the most effective routes to further improve their TE performance are to enhance $\sigma$ and reduce ${\kappa }_{\mathrm{L}}$ through doping.

We present a method for the modeling of fermionic reservoirs using a new class of ancillary damped fermions, dubbed purified pseudofermions, which exhibit unusual free correlations. We show that this key feature, when combined with existing efficient decomposition algorithms for the reservoir correlation functions, enables the development of an easily implementable and accurate scheme for constructing effective models of fermionic reservoirs. We numerically demonstrate the validity, accuracy, efficiency, and potential use of our method by studying the particle transport of spinless fermions in a one-dimensional chain. Beyond its utility as a quantum impurity solver, our method holds promise for addressing a wide range of problems involving extended systems in fields like quantum transport, quantum thermodynamics, thermal engines, and nonequilibrium phase transitions.

We perform unrestricted Hartree-Fock calculations on the two-dimensional Hubbard model on a honeycomb and bilayer honeycomb lattice at both zero and finite temperatures. Finite-size real-space calculations are supplemented with random-phase approximation calculations in the thermodynamic limit. Our motivation comes from high doping levels achieved in graphene and Bernal bilayer graphene by intercalation. We present phase diagrams in doping and temperature for a moderate Hubbard interaction. The magnetic states we find are classified systematically based on the dominant Fourier components of their spin patterns, their average magnetization and spin incommensurabilities. The dominant spin patterns are Néel order and various types of stripes. Around Van Hove filling, we resolve the competition between stripe and chiral spin density waves in the symmetry-broken regime. We also investigate the effect of an applied external displacement field on the spin patterns of Bernal bilayer graphene.

We describe a class of neuralized fermionic tensor network states (NN-fTNSs) that introduce nonlinearity into fermionic tensor networks through configuration-dependent neural network transformations of the local tensors. The construction uses the fTNS algebra to implement a natural fermionic sign structure and is compatible with standard tensor network algorithms but gains enhanced expressivity through the neural network parametrization. Using the 1D and 2D Fermi-Hubbard models as benchmarks, we demonstrate that NN-fTNSs achieve order of magnitude improvements in the ground-state energy compared to pure fTNSs with the same bond dimension and can be systematically improved through both the tensor network bond dimension and the neural network parametrization. Compared to existing fermionic neural quantum states based on Slater determinants and Pfaffians, NN-fTNSs offer a physically motivated alternative fermionic structure. Furthermore, compared to such states, NN-fTNSs naturally exhibit improved computational scaling and we demonstrate a construction that achieves linear scaling with the lattice size.

We present a comprehensive investigation of the structural and electronic properties of Sn-intercalated buffer layers on SiC(0001) using low-temperature scanning tunneling microscopy and spectroscopy (LT-STM and LT-STS), spot-profile analysis low-energy electron diffraction, and density functional theory (DFT) calculations. Sn intercalation effectively decouples the buffer layer, yielding quasifreestanding monolayer graphene while introducing local lattice distortions. Bias-dependent STM imaging revealed the coexistence of conventional and Kekulè-ordered graphene domains, governed by the underlying Sn(1×1) reconstruction at the SiC interface. The measured STS spectra exhibit good agreement with DFT results. However, achieving homogeneous Sn(1×1) domains remains challenging, apparently, due to strain within the Sn monolayer, which drives the emergence of Kekulè distortions and the associated electronic band-gap opening homogeneously in graphene. These findings highlight the crucial role of intercalant homogeneity and strain in tuning graphene's structural and electronic properties.

We theoretically investigate strategies for harnessing quantum interference to optimize the figure of merit $ZT$, power output, and thermodynamic efficiency in multi-quantum-dot Aharonov-Bohm thermoelectric heat engines. Within the nonequilibrium Green's function formalism, we demonstrate that interference effects, such as Fano-type asymmetries, Dicke-like superradiant and subradiant modes, and multipeaked transmission spectra, can be tailored through device geometry, magnetic flux, and dot-lead coupling to produce hybrid transmission profiles that combine features of Lorentzian, boxcar, and Fano line shapes. Such engineered profiles enable configurations that balance the high efficiency of sharp Lorentzian resonances with the high power output of boxcarlike spectra, achieving near-optimal power-efficiency trade-offs. For symmetric quantum-dot arrays in square, pentagonal, and hexagonal configurations, we identify an optimal coupling regime, $t/\gamma \simeq 2$ (with interdot tunneling amplitude $t$ and dot-lead coupling strength $\gamma$), which yields the most favorable trade-off between power and efficiency. In particular, a hexagonal six-dot configuration achieves a $ZT\sim 30$ at dilution temperatures, while the four-dot geometry reaches $\sim 76\%$ of Carnot efficiency with output power $4.74fW$. We further find a direct correspondence between the high-$ZT$ regime and the maximal violation of the Wiedemann-Franz law. Introducing coupling asymmetry between source and drain enhances both efficiency and power. Scaling analysis reveals that efficiency increases systematically with the number of quantum dots, whereas power output reaches its maximum at intermediate system sizes. These results establish coherent control in multidot nanostructures as a viable pathway toward high-performance quantum thermoelectric heat engines, particularly relevant for ultralow-power electronics applications.

Terahertz (THz) laser pulses can drive coherent vibrations through nonlinear phonon coupling, inducing transient lattice distortions that provide an optical pathway for manipulating quantum phases on ultrafast timescales. The excitation of specific phonon modes, in particular, shifts the atomic equilibrium positions, leading to structural distortions and symmetry breaking that alter the properties of symmetry-protected topological quasiparticles. Here, we investigate THz laser-induced nonlinear phonon interactions in the chiral semimetal CoGe, which contains multiple types of topological fermions, and reveal a symmetry-governed switching mechanism of topological states. Under THz excitation, lattice anharmonicity induces net displacements along the $A$ and $E$ Raman modes, breaking the $C_{3,111}$ rotational symmetry and lowering the space group from $P{2}_{1}3$ to its subgroup $P{2}_1{2}_1{2}_1$. Consequently, the unconventional chiral fermions with topological charges of 2 and 4 in CoGe transform into two and four Weyl fermions with the topological charge of 1 in the absence and presence of spin-orbit coupling, respectively. These findings demonstrate that ultrafast symmetry breaking driven by nonlinear phononics enables topological phase transitions of multifold fermions, offering a route for the dynamic control of topological quantum states.

Topological transport phenomena, such as transverse charge, spin, or thermoelectric effects, have attracted significant attention due to both fundamental challenges in their interpretation and their promising spintronic functionalities. Among the most studied phenomena is the anomalous Hall effect (AHE) which can arise from momentum-space or real-space Berry curvature. In most materials, the anomalous Hall response remains below ${10}^3\mathrm{S}/\mathrm{cm}$, with larger values often attributed to extrinsic mechanisms. Here we show that ${\mathrm{CeCoGe}}_3$ exhibits a giant field-induced anomalous Hall conductivity (AHC) exceeding ${10}^5\mathrm{S}/\mathrm{cm}$. We carefully evaluate the intrinsic and extrinsic contributions by comparing samples of different longitudinal conductivity. Remarkably, the intrinsic AHC is over an order of magnitude larger than that of other topological materials, and is the largest value reported to date. Our findings promote ${\mathrm{CeCoGe}}_3$, a noncentrosymmetric strongly correlated Kondo Weyl metal as a platform to study giant anomalous Hall responses.

Through systematic structural predictions and electronic-structure analyses of La-Al intermetallic compounds at ambient pressure, we identify a previously unknown hexagonal phase, ${\mathrm{LaAl}}_5$. In this phase, planar Al-Al bonds assemble into a graphenelike sublattice, while adjacent Al layers are interconnected through additional Al-Al bonds. Extended structural searches of all rare-earth ($R$ = Sc-Lu) and selected actinide ($\mathit{AC}$ = Ac, Th, Pa, U, and Np) aluminides with the composition $(R/AC){\mathrm{Al}}_5$ reveal 16 dynamically stable compounds, confirming the robustness and universality of this graphenelike configuration. Electronic-structure calculations reveal that all these compounds are metallic, with conductivity arising from pronounced hybridization between $\mathrm{Al}\text{−}3p$ and $R/\mathit{AC}-d/f$ states near the Fermi level. The formation of $\sigma$-like Al-Al bonds is driven by electron transfer from $R/\mathit{AC}$ atoms to the Al sublattice, accompanied by redistribution of Al valence electrons. Furthermore, electron-phonon coupling calculations predict weak superconductivity in ${\mathrm{LaAl}}_5$, which is moderately enhanced in ${\mathrm{AcAl}}_5$. Gibbs free-energy calculations show that $(\mathrm{La}/\mathrm{Y}/\mathrm{Sc}){\mathrm{Al}}_5$ could become energetically stable at temperature below 800 K, a regime routinely accessible in aluminide synthesis. These findings provide direct evidence for the existence of graphenelike structures formed by Al atoms and establish a foundation for the experimental realization of this intriguing class of rare-earth aluminides.

The atomic-scale influence of disorder on the topological order can be quantified by a universal topological marker, although the practical calculation of the marker becomes numerically very costly in higher dimensions. We propose that for any symmetry class in higher dimensions, the topological marker can be calculated in a very efficient way by adopting the kernel polynomial method. Using class AII in three dimensions as an example, which is relevant to realistic topological insulators such as ${\mathrm{Bi}}_2{\mathrm{Se}}_3$ and ${\mathrm{Bi}}_2{\mathrm{Te}}_3$, this method reveals the criteria for the invariance of topological order in the presence of disorder, as well as the possibility of a smooth crossover between two topological phases caused by disorder. In addition, the significantly enlarged system size in the numerical calculation implies that this method is capable of capturing the quantum criticality much closer to topological phase transitions, as demonstrated by a nonlocal topological marker.

The $R{\mathrm{Mn}}_2{\mathrm{Ge}}_2$ ($R=\mathrm{rare}$ earth) intermetallic compounds have garnered significant attention owing to their diverse magnetic structures and magnetotransport responses. Here, we report the anisotropic magnetic properties, magnetoresistance (MR), magnetostriction (MS), and magnetocaloric (MC) effect in a $\mathrm{Dy}{\mathrm{Mn}}_2{\mathrm{Ge}}_2$ single crystal. With decreasing temperature, the Mn subsystems exhibit antiferromagnetic (AFM) ordering, while the Dy moments undergo ferromagnetic ordering at a critical temperature, resulting in an intermediate state between $T_0\sim 39.6\mathrm{K}$ and $T_1\sim 34.2\mathrm{K}$. Below $T_1$, the AFM interaction between the Mn and Dy subsystems results in a ferrimagnetic phase. Three field-induced phase transitions are observed along the $c$ axis. The transitions occurring below $T_1$ and above $T_0$ demonstrate pronounced metamagnetic characteristics. When the current is applied along the $a$ axis and the magnetic field along the $c$ axis, positive and negative MR effects with significant changes are observed at the critical magnetic field of the metamagnetic transitions below $T_1$ and above $T_0$, respectively. A substantial positive MR of +81% is observed at 20 K under 9 T. Upon applying physical pressure, the MR effect is significantly reduced. During the metamagnetic transitions, a remarkable MS effect is observed, indicating strong spin-lattice coupling. The responses of Dy and Mn sublattices to the magnetic field yield a maximum magnetic entropy change of $18.84\mathrm{J}\mathrm{k}{\mathrm{g}}^{-1}{\mathrm{K}}^{-1}$ along the $c$ axis under the field change of 0–7 T near $T_0$, suggesting a giant MC effect. This MC effect shows a plateaulike behavior across a broad temperature window from 39 to 60 K, making it a promising candidate for magnetic refrigeration applications.