The magnetic nature of the altermagnet candidate ${\mathrm{RuO}}_2$ remains under debate. It has been recently shown from quantum oscillations and angle-resolved photoemission spectroscopy that the high-quality ${\mathrm{RuO}}_2$ bulk single crystal is a paramagnetic metal. Here we report the specific heat and magnetic susceptibility in ultraclean ${\mathrm{RuO}}_2$ single crystals with residual resistivity ratio up to 1200. The electronic specific heat, the magnetic susceptibility, and the $T^2$ coefficient in resistivity point to a weakly correlated three-dimensional Fermi-liquid state, as supported by the Wilson and Kadowaki-Woods ratios. The magnetic susceptibility increases with temperature and is phenomenologically fitted with an inclusion of $T\text{ln}(T/T_0)$ over a wide temperature range up to 400 K. In contrast, the energy dependence of the density of states and thermal activation of quasiparticles lead to a decrease with temperature. Such characteristic temperature dependence, similar to that observed in other $d$-electron metals, is attributable to an enhanced orbital contribution arising from lattice-expansion-induced changes in the band structure.

Here we argue that the angular harmonics of magnetotransport directly characterizes carrier imbalances in a multiband semimetal. A robust threefold modulation superimposed on the conventional $cos\theta$ angular Hall response is observed in ${\mathrm{WTe}}_2$ in the metallic regime at low temperatures under out-of-plane magnetic-field rotation. By tuning temperature and thickness, we demonstrate that this modulation is intrinsic and originates from enhanced nonlinear Hall response arising from its near-compensated two-band electronic structure. In contrast, a few-layer graphene exhibits a richer hierarchy of higher-order angular harmonics, consistent with its multiple dynamically distinct bands. By carefully ruling out extrinsic artefacts and employing Fourier analysis, we establish angular harmonic analysis as a sensitive probe of electronic structure in multiband semimetals.

Spin qubits are a promising platform for quantum computation and can operate at temperatures ranging from tens of millikelvin to a few kelvin. Some recent experiments have revealed a nontrivial, often nonmonotonic dependence of the qubit frequency on temperature, including regions of reduced temperature sensitivity. Motivated by these observations, we investigate whether the interaction of a spin qubit with phonons of the host material can contribute to such frequency shifts in the low-temperature regime. While the resulting shifts are too small to quantitatively account for the experimentally observed magnitudes, our analysis reproduces several qualitative features, including nonmonotonic temperature dependencies and sign changes of the frequency shift. More generally, we demonstrate that phonons can induce a temperature-dependent renormalization of the qubit frequency and provide insight into the interaction between spin qubits and their host material. Understanding and quantifying such individual contributions is an important step toward identifying the microscopic mechanisms underlying the experimentally observed temperature dependence of spin-qubit frequencies.

Skyrmions are topologically protected solitons with great potential as information carriers. Initially explored in condensed-matter physics, they have recently garnered much attention in photonics. Photonic skyrmions constructed from magnetic field vectors in electromagnetic waves are typically localized, long-range propagating skyrmions. They possess both theoretical and practical significance but remain elusive. Here, we report a class of high-fidelity optical counterparts capable of propagating over long distances in tubular structures, which satisfy the exact wave solutions of Maxwell's equations. By leveraging transformation optics to connect the material parameters with the vector field, the intrinsically twisted skyrmions with customized helicity are predicted in an anisotropic waveguide, where the required material parameters can be realized through effective medium theory. These propagating skyrmions with abundant helicity provide additional degrees of freedom to manipulate electromagnetic waves across space and time, further paving the way for applications in chiral sensing, information transmission, and storage.

We show that magnetism in moiré Mott-Wigner crystals can be induced by the collective vibration of electrons around their equilibrium positions (namely, electronic phonons), even without the electron-electron spin interaction. Due to a geometric valley-orbit coupling from the Berry phase effect, the zero-point energy of electronic phonons reaches minimum when electrons are fully valley polarized. This leads to a spontaneous magnetization when below a critical temperature. We further propose engineering magnetism in Mott-Wigner crystals through the photoexcitation of chiral electronic phonons.

Twisted van der Waals (vdW) bilayers can support tunable surface/hyperbolic phonon polaritons (S/HPhPs) depending on the interlayer twist angle. S/HPhPs can be thermally excited and significantly modify the thermal near field. A photonic topological transition occurs at a critical twist angle, where the polariton dispersion switches from hyperbolic to elliptical. Because the twist angle governs the polariton modes, it is intrinsically linked to the optical helicity density (OHD) of the near-field thermal emission. In this work, a relationship between the OHD of near-field emission and the twist angle of twisted bilayer vdW materials is identified and investigated. To evaluate the OHD, a $3\times 3$ coherence-matrix method is derived from the fluctuation-dissipation theorem (FDT), which provides a complete description of the thermal electromagnetic field of the twisted bilayer and a formalism for OHD based on the polarization matrix is employed. The topological transition angle (TTA) is determined by calculating the polariton dispersion of the vdW bilayer at different twist angles. A strong correlation between the OHD and TTA is observed. This behavior is associated with polariton canalization and the asymmetric polariton modal response. In this study, we provide insights into the analysis of angular momentum in near-field thermal radiation from twisted vdW structures.

We perform an investigation of the quantum transmission in a quantum wire that is coupled locally to a nonreciprocal quantum chain. Our findings reveal that in this system, the quantum transmission properties are determined by the characteristics of the quantum chain. For the case of the Hermitian chain, it induces abundant antiresonance and bound states in continuum, governed by the length parity of the chain and the wire-chain coupling manner. Next, when nonreciprocal couplings are incorporated in the quantum chain, more Fano antiresonance points are allowed to appear in the transmission function spectra, accompanied by the disappearance of the bound states in continuum. Besides, with the lengthening of the quantum chain, the antiresonance points are transformed into a well-defined insulating band in the transmission function spectra. Further analysis suggests that except the Fano antiresonance, the occurrence of the non-Hermitian skin effect induces additional suppression of the quantum transmission, which leads to the formation of an insulating band. We conclude that this research provides valuable insights for the transmission properties in quantum systems featuring nonreciprocal couplings.

We investigate the thermodynamic properties of elemental cerium by assessing the crucial role of phonon free energy within the framework of dynamical mean-field theory (DMFT). While conventional density functional theory (DFT) often fails to capture the intricate energy landscape of $f$-electron materials, our approach integrates many-body electronic correlations with lattice dynamics to achieve a more rigorous description of the equation of state. We calculate the total energy as a function of the lattice constant at both the DFT and $\mathrm{DFT}+\mathrm{DMFT}$ levels, subsequently incorporating the vibrational free energy derived from the phonon density of states. Our findings reveal that electronic renormalization of the force constants significantly alters the phonon spectra, particularly in the strongly correlated $\gamma$ phase. By applying these phonon corrections to the energy profiles, we observe a substantial refinement in the predicted equilibrium volumes. Using principal component-based machine learning, we interpolate phonon dispersions continuously from a finite set of first-principles calculations and compare them with experiment, finding significantly closer agreement than conventional DFT and $\mathrm{DFT}+\mathrm{U}$ calculations that neglect dynamical many-body correlations. This study underlines the necessity of accounting for both electronic and vibrational entropy when evaluating the phase stability and structural transitions of lanthanide systems under varying pressures and temperatures.

Surface confined electronic states provide a fertile ground for discovering emergent phenomena that have no counterpart in the bulk, offering new routes to manipulate correlations, symmetry breaking, and dimensionality at the atomic scale. Here, we show that charge density wave (CDW) symmetry breaking can yield surface states in $1\mathrm{T}\text{−}{\mathrm{TiSe}}_2$. Micro–angle-resolved photoemission spectroscopy ($\mu$-ARPES) resolves a sharp, two-dimensional surface resonant state (SRS) that emerges within the CDW reconstructed low energy spectrum. The SRS exhibits notable temperature dependence and its spectral weight collapses around $\sim 160\mathrm{K}$, while CDW transition temperature $T_{\mathrm{CDW}}$ is commonly reported as $\approx 202\mathrm{K}$. Slab $\mathrm{DFT}+U$ calculations reproduce a surface localized resonance when CDW folding brings valence and conduction states into near degeneracy, suggesting a correlation tuned, surface selective origin. These results point to a form of correlation-tuned surface resonance in a layered CDW compound and suggest a framework for engineering low-dimensional quantum states in van der Waals materials via symmetry breaking and electronic structure tuning.

We introduce a functional renormalization group framework formulated directly in the Floquet steady state that systematically incorporates frequency-dependent interaction effects. By retaining the frequency structure of the two-particle vertex up to second order in interaction strength, our approach provides controlled access to dynamical response functions and nonequilibrium transport in driven, interacting systems. Using the periodically driven single-impurity Anderson model as a paradigmatic example, we benchmark our results against state-of-the-art Floquet Green's function methods and find quantitative agreement for finite-frequency observables up to intermediate interaction strengths. Remarkably, we also show that static properties are often captured reliably by much simpler approximations, suggesting practical pathways for modeling driven quantum materials. Finally, we demonstrate that although periodic driving of the dot strongly broadens the Kondo resonance through inelastic scattering, it leaves the many-body Kondo cloud largely intact. This robustness suppresses Floquet replicas of the Kondo peak and leads to a partial persistence of Kondo pinning, highlighting the resilience of emergent many-body correlations under local periodic driving.

Twisted bilayer hyperbolic metasurfaces provide versatile control over surface-wave dispersion via rotational stacking, enabling highly directional canalization and flexible wave-front engineering. While prior studies have mainly focused on hyperbolic eigenmodes, the behavior of antihyperbolic surface waves—characterized by distinct polarization and substantially smaller wave vectors—remains largely unexplored. Here, we investigate antihyperbolic surface waves in twisted bilayer hyperbolic metasurfaces, revealing that their isofrequency contours undergo a topological reconfiguration from open to closed at a critical twist angle. Furthermore, we find that tuning the interlayer separation of bilayer metasurfaces can induce the conversion between anisotropic and isotropic surface-wave propagation. These findings demonstrate that antihyperbolic eigenmodes can offer a method for dispersion engineering in nanophotonics, paving the way for advanced wave-front control and topological photonic devices.

Near-field radiative heat transfer (NFRHT), which can surpass the blackbody limit by orders of magnitude through evanescent waves like surface plasmon polaritons (SPPs), holds great promise for advanced thermal management and energy conversion. A central challenge is achieving dynamic, nonreciprocal control over heat flow. This work proposes a scheme for velocity-programmed nonreciprocal thermal radiation using graphene. We develop a comprehensive fluctuational-electrodynamics framework that self-consistently incorporates both macroscopic plate motion, described by Lorentz transformations, and microscopic carrier drift, captured by a nonlocal, non-reciprocal conductivity model. This dual-velocity approach allows active sculpting of the SPP dispersion in momentum space, thereby tailoring the photon-tunneling probability in a directional manner. We demonstrate that by merely adjusting the relative velocities—while maintaining both plates at an identical temperature (300 K)—the net heat flux can be continuously tuned from strong forward to strong reverse flow, passing through multiple zero-crossing points. Momentum-space analyses provide a clear physical picture: the programmable heat flux originates from the Doppler-shifted mismatch or alignment of the SPP dispersions of the two graphene sheets. This work establishes a platform for active thermal photonics, where heat flow becomes a dynamically programmable function of velocity, with implications for on-chip thermal routing, adaptive thermal management, and energy recovery systems.

We study dilute two-dimensional systems of interacting excitons with a moat dispersion, whose ground-state manifold consists of a set of discrete or continuously degenerate energy minima. At low densities and in the presence of contact interactions, it is known that the bosons can undergo statistical transmutation and give rise to a chiral spin liquid. Here, we show that long-range interactions such as those expected in excitonic systems introduce a rich competition between the chiral spin liquid and different kinds of Bose-Einstein condensates. The moat dispersion can favor Bose-Einstein condensation into states occupying multiple momenta, leading to inhomogeneous and supersolid phases with a highly anisotropic superfluid response. We demonstrate that a proper $T$-matrix renormalization of the exciton-exciton interaction is essential for describing these phases and show that they can arise even from purely repulsive interactions. This formalism is employed to obtain the phase diagram of competing homogeneous and stripe condensates with the chiral spin liquid in an electron-hole bilayer model. In addition, we show how the $T$ matrix enters the familiar Gross-Pitaevskii framework and map out extended phase diagrams within a pseudopotential approximation. We place our findings in the context of real excitonic systems by discussing the roles of finite lifetimes, disorder, band-structure warping, and nonzero temperatures. We conclude that moat bands can drive Bose-Einstein condensation and supersolidity already at weak coupling, in contrast to the case of a standard parabolic dispersion.

Our understanding of vibrations in solids currently rests on concepts and techniques designed for crystals and explicitly relying on periodicity, hence inapplicable to amorphous materials. As a consequence, no established framework enables a systematic decomposition of the vibrational spectrum of amorphous solids into contributions associated with well-defined types of atomic motions. This methodological gap obscures the interpretation of various experimental probes of linear response, based on the measurements of acoustic, thermal, or optical properties. Here, we construct such a framework—Recursive Orthogonal Splitting Analysis (ROSA)—which decomposes the vibrational space by recursive applications of the projection formalism. Each step of the procedure exploits a dominant stiffness contrast to split a vibrational displacement subspace into two weakly coupled orthogonal complements. We illustrate ROSA by applying it to the archetypal covalent glass—vitreous silica. Successively separating bond-stretching, symmetric and antisymmetric oxygen motions, isotropic and deviatoric tetrahedral strains, and distinct classes of tetrahedral bending, reveals a hierarchical structure of the space of vibrational degrees of freedom, involving six mutually orthogonal subspaces. These subspaces selectively capture all salient spectral features, including the two-humped structure in the low-frequency range, the peak near $800{\mathrm{cm}}^{-1}$, and the high-frequency doublet. In the low-frequency range, rigid-unit tetrahedral rotations do not constitute independent degrees of freedom but are kinematically enslaved to bending coordinates by no-stretch constraints. Because ROSA relies solely on the existence of contrasted stiffness scales associated with the point symmetry of local structural units, and on their separation by enforcing geometric constraints via the projection formalism, it is directly applicable to a broad class of covalent network glasses.

The zero-field magnetic ground state of the superconducting polar semimetal $\mathrm{EuAuBi}$ is determined using neutron powder diffraction. The system realizes a commensurate antiferromagnetic ground state of wave vector $\mathbf{k}=(1/3,0,0)$ with moments along the crystallographic $b$ axis and unequal moment amplitudes between the two magnetically inequivalent Eu orbits. On warming above an intermediate transition temperature, $T_{\mathrm{N}2}\approx 3.3\mathrm{K}$, a commensurate-incommensurate transition occurs with $\mathbf{k}\left(T\right)=[1/3-\delta (T),0,0]$, preserving the moment direction and occurring only within a narrow temperature window below the incommensurate-paramagnetic transition at $T_{\mathrm{N}1}\approx 4\mathrm{K}$. A minimal isotropic exchange toy model including interactions up to third-nearest neighbors suggests the presence of competing interactions. Together, these results provide a foundation for future studies of materials hosting an interplay between magnetism, superconductivity, and electric polarity.

We perform the variational Monte Carlo calculation for recently proposed chiral superconducting states driven by strong Coulomb interactions. We compare the resulting energetics of these electronic phases for the electron dispersion relation $E_k=c_2{k}^2+c_4{k}^4$. Motivated by the recent discovery of chiral superconductivity in rhombohedral graphene systems, we apply our analysis to relevant parameter regimes. We demonstrate that topological chiral superconducting phases (including a spin-unpolarized state) can be energetically favored over the spin-valley polarized Fermi liquid above the density of Wigner crystal phase. Our results show that the preference for chiral superconductivity is strongest when $c_2$ lies between zero and a negative value corresponding to a Fermi sea on the verge of forming a hole pocket around $k=0$. This finding suggests that superconductivity can arise from pure repulsive Coulomb interactions in systems with an almost flat band bottom, without relying on the pairing instability of a Fermi surface. This mechanism opens a new pathway to superconductivity beyond the conventional BCS mechanism.

Zintl-phase compounds ${AM}_2{\mathrm{Pn}}_2$ ($A=\mathrm{Ca}$, Sr, Ba; $M=\mathrm{Zn}$, Cd; $\mathrm{Pn}=\mathrm{N}$, P, As, Sb) have recently garnered growing attention in photovoltaic applications. Herein, we systematically investigate some key physical properties (quasiparticle band structures, exciton binding energies, and optical absorption coefficients) of these Zintl-phase materials as solar absorbers via first-principles calculations combining with the $G_0{W}_0$ approximation and Bethe-Salpeter equation. We demonstrate that the $G_0{W}_0@\mathrm{PBE}$ approach accurately predicts the band gaps of ${AM}_2{\mathrm{Pn}}_2$ compounds with $\mathrm{Pn}=\mathrm{P}$, As, and Sb, whereas $G_0{W}_0@\mathrm{LDA}+U$ achieves better consistency with experimental data for the ${AM}_2{\mathrm{N}}_2$ series. Calculated optical absorption spectra indicate that ${\mathrm{CaZn}}_2{\mathrm{P}}_2$ and ${\mathrm{SrZn}}_2{\mathrm{P}}_2$ exhibit relatively wide band gaps, rendering them promising candidates for top cells in tandem solar configurations. In contrast, ${A\mathrm{Cd}}_2{\mathrm{P}}_2$ ($A=\mathrm{Ca}$, Sr, Ba) and ${A\mathrm{Zn}}_2{\mathrm{N}}_2$ ($A=\mathrm{Ca}$, Sr, Ba) feature band gaps well suited for single-junction solar cells, while ${AM}_2{\mathrm{As}}_2$ and ${\mathrm{CaCd}}_2{\mathrm{Sb}}_2$, with narrower band gaps, are more suitable for bottom cells in tandem devices. Furthermore, the low exciton binding energies and small carrier effective masses of ${AM}_2{\mathrm{Pn}}_2$ compounds further underscore their potential for photovoltaic applications.

Flat bands host compact localized states arising from destructive interference and exhibit enhanced sensitivity to weak perturbations, making them a versatile arena for band-geometry engineering. The present geometry-tunable splitting provides a linear-wave analog of flat-band reconstruction, enabling controllable gaps without invoking intrinsic nonlinearity. This work demonstrates that in a two-dimensional periodic conductor array of Lieb lattice, interlayer inductive coupling enables the single-layer zeroth-order flat band to split into two Even-Odd branches that are continuously tunable. Due to the mutual inductance depending on the interlayer spacing, geometry-induced hybridization gap is realized without nonlinear elements. Circuit theory and numerical analysis validate the approach, advancing geometry-based band engineering and reconfigurable photonics.

Attaining a reliable complete basis set (CBS) limit remains a significant challenge in ab initio correlated electronic-structure calculations. Building on our previous work for atoms and diatomic molecules, we present a finite-element (FE) Delta-Sternheimer approach for numerically accurate random-phase approximation (RPA) calculations applicable to general molecules. This approach seamlessly integrates atomic orbital basis sets with FE grids, enabling an arbitrarily precise representation of the first-order variation of the wave function. As a result, the density response function and RPA correlation energies can be computed with fully controlled numerical precision. The Delta-Sternheimer approach thus provides direct access to RPA correlation energies at the CBS limit, eliminating reliance on conventional extrapolation schemes. We apply this approach to two problems: The energy hierarchy of 20 water-dimer configurations and the atomization energies of 50 molecules from the G2 set. For the water dimer, we examine the basis set dependence of the isomer energy ordering. For the G2 set, we investigate the residual numerical uncertainty in the conventional extrapolated CBS limit, both with and without correction for basis-set superposition error.

Jackiw-Rebbi zero modes were first proposed in 1976 as topologically protected zero-energy states localized at domain walls in one-dimensional Dirac systems. They have attracted widespread attention in the field of topological quantum computing, as they serve as nonsuperconducting analogs of Majorana zero modes and support non-Abelian statistics in topological insulator systems. However, compared to their Majorana cousins, the braiding properties of Jackiw-Rebbi zero modes are vulnerable to the on-site energy deviation between the modes involved in the experiment. In this work, we propose to estimate the braiding properties of Jackiw-Rebbi zero modes through measurements of transport signatures, which are readily measurable in current experiments. We find that the fidelity of the braiding operation reaches unity when the current noise is fully suppressed, while this braiding fidelity monotonously decreases with the increasing of the current noise. Based on these transport signatures, we further discuss the correspondence between Majorana and Jackiw-Rebbi zero modes, highlighting their similarity in supporting non-Abelian statistics.