Uranium $5f$ electrons often yield heavy-fermion behavior via Kondo screening. However, the pronounced bad-metallic transport of uranium mononitride (UN) defies an incoherent Kondo explanation. Using density-functional theory combined with dynamical mean-field theory, we show that UN is a strongly correlated bad metal. The dominant correlations arise from intra-atomic Hund's exchange interaction between two $5f$ electrons, which aligns local magnetic moments and produces large quasiparticle mass renormalization. This identifies UN as a $5f$-electron analog of a Hund's metal—a paradigm chiefly associated with transition-metal $d$ systems. Our results motivate a reexamination of the interplay between Mott, Kondo, and Hund-driven correlations across actinide correlated materials.

We investigate fluctuation-dominated physics in a superconductor–insulator–superconductor Josephson junction modeled by a Bogoliubov–de Gennes Hamiltonian. The resulting free-energy functional, expanded in powers of the fluctuations, depends explicitly on the imbalance between the absolute values of the fluctuations in the two electrodes. By solving a Ginzburg-Landau equation for this imbalance field, we determine its spatial configuration and the corresponding Josephson current. Going beyond the harmonic approximation for the effective potential reveals the emergence of a regime characterized by singular behavior of the Josephson current.

We investigate the use of Berry curvature dipole in $n$-doped tellurium as a mechanism for achieving terahertz amplification and lasing by applying a DC electric field. When the electrical bias and wave vector are aligned along the trigonal $c$ axis, the right-handed circularly polarized mode experiences amplification at relatively low bias, while the left-handed mode is attenuated. Furthermore, when the electrical bias and wave vector are orthogonal to the $c$ axis, the structure supports elliptically polarized eigenmodes that also exhibit gain under suitable bias conditions, where the degree of ellipticity is tunable by the applied bias. We also investigate lasing conditions for a Fabry-Perot cavity incorporating biased Te as an active medium. Due to the resonance in the dielectric permittivity of tellurium, there are discrete lasing intervals. Our results show that bulk chiral tellurium could be used as an electrically tunable, polarization-selective gain medium for micrometer-scale terahertz lasers, with lasing achievable at bias fields below the material's breakdown threshold, paving the way towards new terahertz devices.

We investigate finite two-dimensional disordered systems with periodic confinement. At low energies, eigenstates exhibit strong Anderson localization, while at higher energies a subset of states exhibits variational scarring with anisotropic intensity patterns that deviate from random-wave expectations. Scaling theory predicts that in two dimensions all eigenstates localize in the large-system-size limit, yet the energy-dependent localization length and finite-size effects allow these regimes to coexist. We demonstrate that this coexistence produces distinct, robust signatures in both spatial intensity patterns and spectral statistics that are directly observable in mesoscopic electronic, photonic, and cold-atom systems.

The quantum anomalous Hall effect shows great promise for the realization of the ohm without the need for an external magnetic field. The most mature material platform is magnetically doped topological insulators. In these materials, precise quantization is limited to low temperatures, with the activation energy for dissipative transport typically in the range of $1\mathrm{K}$. One potential source of dissipative transport is nonchiral edge states. These states are expected to be present in sufficiently thick samples. In this work, we perform extensive Hall and nonlocal resistance measurements in a Hall bar geometry at 2 K. We perform 15 distinct measurements on a single device, each independent with respect to device symmetry and Onsager reciprocity. By comparing the results to different transport models, we find that the system behavior is well described by a simple continuum Ohm's law model. The addition of nonchiral edge states to the model does not significantly improve the fitting, and we conclude that there is not strong evidence for these states. We discuss the implications of our results for the prospect of a high-temperature quantized anomalous Hall effect in these materials.

We present an improved version of the algorithm contracting and optimizing finite projected entangled pair states (fPEPS) in conjunction with projected entangled pair operators (PEPOs). Our work has two components to it. First, we explain in detail the characteristic contraction patterns that occur in fPEPS calculations and how to slice them such that peak memory occupation remains minimal while ensuring efficient parallel computation. Second, we combine controlled bond expansion [A. Gleis, J.-W. Li, and J. von Delft, Phys. Rev. Lett. 130, 246402 (2023)] with randomized singular value decomposition [V. Rokhlin, A. Szlam, and M. Tygert, SIAM J. Matrix Anal. Appl. 31, 1100 (2009)] and apply it throughout the fPEPS algorithm. We present benchmark results for the Hubbard model for system sizes up to $8\times 8$ and SU(2) symmetric bond dimension of up to $D=6$ for PEPS bonds and $\chi =500$ for the environment bonds. Finally, we comment on the state and future of the fPEPS-PEPO framework.

Recently, the first successful synthesis of bulk manganese monocarbide (MnC) has been reported. The compound crystallizes in the zinc-blende structure and has been proposed as a potential superhard material. In this work, we present a comprehensive first-principles study of the structural, electronic, and magnetic properties of MnC using several exchange-correlation approximations. We demonstrate that the SCAN meta-GGA (generalized gradient approximation)  and the Perdew-Burke-Ernzerhof zero revised (PBE0r) hybrid functional outperform GGA–Perdew-Burke-Ernzerhof for solids (PBEsol), Heyd-Scuseria-Ernzerhof 2006 (HSE06), and the mean-field density functional theory [($\mathrm{DFT}\left)\right]+U+V$ schemes in correctly predicting the experimentally observed zinc-blende structure as the ground state. Our analysis reveals that the bond-exchange interaction plays a decisive role in stabilizing this phase. At theoretical equilibrium, hybrid functionals (PBE0r and HSE06) predict a metallic ground state, whereas semilocal functionals (PBEsol and SCAN) and $\mathrm{DFT}+U+V$ yield two distinct types of half-metallic ferromagnetism with opposite volume dependence, opening a debate on the origin and nature of this behavior. If confirmed experimentally, such a property would make MnC an attractive candidate for spintronic applications.

We introduce two classes of junctions in a toric code, a prototypical model of a ${\mathbb{Z}}_2$ quantum spin liquid, and study the nature of anyonic transport across them mediated by Zeeman fields. In the first class of junctions, termed potential barrier junctions, the charges sense effective static potentials and a change in the band mass. In a particular realization, while the junction is completely transparent to the electric charge, magnetic charge transmission is allowed only after a critical field strength. In the second class of junctions, we stitch two toric codes with operators which do not commute at the junction. We show that the anyonic transmission gets tuned by effective pseudospin fluctuations at the junction. Using exact analytical mappings and numerical simulations, we compute charge-specific transmission probabilities. Our work, apart from uncovering the rich physical mechanisms at play in such junctions, can motivate experimental work to engineer defect structures in topologically ordered systems for tunable transport of anyonic particles.

The Kondo effect is a hallmark of strongly correlated systems, where an impurity's local degrees of freedom are screened by conduction electrons, forming a many-body singlet. With increasing degrees of freedom in the impurity, theoretical studies face significant challenges in accurately identifying and characterizing the underlying mechanisms that screen the impurity. In this work, we introduce a straightforward yet powerful methodology for identifying the formation of Kondo singlets and their screening mechanisms, by utilizing the numerical renormalization group combined with the matrix product states technique. We demonstrate the effectiveness of our method on the single and two-level Anderson impurity models. Furthermore, we outline generalizations to multichannel and multiorbital Kondo impurities, showing how advanced tensor network techniques render our approach a versatile framework for tackling complex impurity systems.

Indium phosphide (InP) has attracted significant interest in high-frequency electronics, optoelectronics, and photovoltaics due to its wide band gap, high electron saturation velocity, and superior electron mobility. However, its relatively low hole mobility remains a pivotal bottleneck for practical applications. This study, employing mode-level first-principles calculations, elucidates that interband electron-phonon scattering is the primary factor limiting hole mobility in InP. Our results show that uniaxial strain induces splitting of the light-hole ($lh$) and heavy-hole ($hh$) bands near the valence band maximum. This splitting significantly suppresses the $lh-hh$ interband scattering, thereby substantially enhancing hole mobility. Furthermore, tailored uniaxial strain can enhance electron mobility by reducing scattering rates near the conduction band minimum. Specifically, our predictions indicate that hole mobility in InP along the [100] and [001] directions increases by approximately $240\%$ and $88\%$, respectively, under uniaxial compressive strain of $4\%$. These findings uncover a carrier transport mechanism and provide a generalized strategy for enhancing hole mobility in zinc-blende semiconductors.

Type-II hyperbolic lattices constitute a new class of hyperbolic structures that are projected onto the Poincaré ring and possess both an inner and an outer boundary. In this work we reveal the higher-order topological phases in type-II hyperbolic lattices, characterized by the generalized quadrupole moment. Unlike the type-I hyperbolic lattices where zero-energy cornerlike states exist on a single boundary, the higher-order topological phases in type-II hyperbolic lattices possess zero-energy cornerlike states localized on both the inner and outer boundaries. These findings are verified within both the modified Bernevig-Hughes-Zhang model and the Benalcazar-Bernevig-Hughes model. Furthermore, we demonstrate that the higher-order topological phase remains robust against weak disorder in type-II hyperbolic lattices. Our work provides a route for realizing and controlling higher-order topological states in type-II hyperbolic lattices.

Single atomic wires of transition metal compounds have been successfully isolated within carbon nanotubes. These real one-dimensional (1D) materials with enhanced electron-electron correlations and strong electron-phonon coupling provide a unique platform to explore the competition and synergy among different quantum phases. Here we predict a new single atomic wire of niobium triiodide (${\mathrm{NbI}}_3$). Under the ${\mathrm{D}}_{2\mathrm{h}}$ symmetry, pronounced states from localized Nb-$d$ orbitals emerge at the Fermi level, inducing strong electron correlations and instability. Inclusion of Hubbard $U$ leads to a metal-to-insulator transition. Simultaneous Peierls dimerization occurs and coexists with the Mott state. Consistently, our first-principles calculations identify a ground state with ${\mathrm{C}}_{2\mathrm{v}}$ symmetry in ${\mathrm{NbI}}_3$ atomic wire and antiferromagnetic order featuring strong magnetic anisotropy. Notably, the bands near the gap remain nearly flat with narrow bandwidths irrespective of the $U$ value, indicating strongly suppressed electron kinetic energy. These results shed light in exploring correlated physics in single atomic wires and pave the way for quantum devices governed by the interplay between spin and charge orders.

$T_d$ phase type-II Weyl semimetals are of technological interest in part due to their novel sliding ferroelectricity and nontrivial topology being dependent on their van der Waals stacking orders. Optical manipulation of these stacking orders via interlayer sliding can lead to new types of energy-efficient ultrafast memory and topological switches. Despite the existing reports on $T_d$ phase $\mathrm{WT}{\mathrm{e}}_2$ and $\mathrm{MoT}{\mathrm{e}}_2$, such light-driven sliding dynamics are unexplored in ternary $\mathrm{TaIr}{\mathrm{Te}}_4$, a material that has recently demonstrated more pronounced topological properties and greater environmental stability. Here we apply an ultrafast near-infrared pulse to bulk $\mathrm{TaIr}{\mathrm{Te}}_4$ and observe a $15\text{−}\mathrm{c}{\mathrm{m}}^{-1}$ coherent interlayer shear phonon in both transient reflectivity and time-resolved second harmonic generation (TRSHG). The initial cosinelike phase of this oscillation is characteristic of a displacive excitation mechanism, evidencing a pump-induced excited state distortion along the interlayer sliding coordinate. With increasing pump fluence, the temporal phase of the oscillation undergoes a π phase shift. We exclude a sliding ferroelectric switching origin using phase-sensitive TRSHG, instead concluding that the coherent phonon phase shift arises from inversion of the sliding distortion direction, supported by first-principles calculations of the crystal polarization. Our findings advance the understanding of nonequilibrium properties in layered topological semimetals and may serve as proof of principle for ultrafast electronics based on terahertz-speed modulation of the symmetry-dependent topological properties of $\mathrm{TaIr}{\mathrm{Te}}_4$.

We numerically study topological effects of electromagnetic (EM) waves in a two-dimensional non-Hermitian photonic crystal composed of lossy magneto-optical materials. In this system, not only the EM wave functions but also the complex eigenfrequencies exhibit nontrivial topological properties. We demonstrate that the non-Hermitian skin effect, protected by point gaps in the complex eigenfrequency spectrum, emerges at both the edges and corners of truncated structures. This phenomenon has no counterpart in Hermitian systems. In addition, we identify non-Hermitian topological edge states originating from the nontrivial topology of the bulk bands. While most previous studies of non-Hermitian topology have focused on tight-binding models, our work addresses a continuous photonic system, providing a more realistic platform and offering a concrete route toward experimental realization of non-Hermitian effects.

The spin-dependent transport properties and spin polarization through a time-periodic potential well in the altermagnet are investigated. Photon-assisted transport occurs in periodically driven quantum systems, where incident electrons can exchange energy with the driven field by absorbing or emitting photons (in units of $\hslash \omega$), leading to transitions between electron channels. The photon-assisted tunneling spectrum in the altermagnet features Fano resonances with asymmetric line shapes, where the resonance energy is located exactly at $E=E_b+\hslash \omega$ ($E_b$ is the bound-state energy in the static potential). The transport is spin-polarized and depends sensitively on the orientation of the altermagnet relative to the interface. Compared with conventional ferromagnetic and antiferromagnetic mechanisms, the transmission in our system presents alternating zero or nonzero net magnetization. These orientation-dependent transport characteristics highlight the unique nature of the altermagnetic state.

Multi-Q magnets consist of superposed spin-density waves with distinct magnetic modulation vectors, enabling a wide range of magnetic orders depending on their combination. Among them, topologically nontrivial spin textures, such as a magnetic skyrmion, have been extensively studied owing to the emergence of topological Hall effects induced by real-space scalar spin chirality. Contrary to this expectation, we theoretically investigate another route to enhancing the Hall response under a topologically trivial double-Q spin textures with neither net scalar spin chirality nor a nonzero skyrmion number. Despite the cancellation of the scalar spin chirality, the double-Q magnetism exhibits a Hall response significantly larger than that of the ferromagnetic phase with a nonmonotonic dependence on the uniform magnetization, which is in stark contrast with a ferromagnetic state and a single-Q spiral state. Analyzing the multiorbital Kondo lattice model, we show that orbital hybridization induced by the double-Q superstructure result in a proliferation of Berry curvature hot spots in $\mathbf{k}$ space, thereby giving rise to a large anomalous Hall effect (AHE). This mechanism accounts for the observed giant AHE in ${\mathrm{GdRu}}_2{\mathrm{Si}}_2$ and ${\mathrm{GdRu}}_2{\mathrm{Ge}}_2$, thereby highlighting topologically trivial double-Q spin textures as promising spintronic materials.

Mesoscopic transport measurements are underexplored as probes of quasiparticles and their properties in correlated metals. The mixed valence compound ${\mathrm{YbAl}}_3$ exhibits a single-ion Kondo temperature of 670 K, while thermodynamic and transport properties (probed with specific heat, magnetic susceptibility, Hall effect, and resistivity) imply the onset of coherence of heavy fermion quasiparticles at $T^{*}\approx 37$ K. To characterize these quasiparticles, we utilize mesoscopic techniques familiar from weakly correlated conductors. In lithographically defined nanowires etched from epitaxial films, we observe weak antilocalization magnetoresistance and universal conductance fluctuations, consistent with electronic coherence lengths of tens of nanometers. Additionally, analysis of Johnson-Nyquist noise measurements as a function of bias current reveal, within the context of a range of accepted models, a significant electron-phonon energy loss that increases with decreasing temperature, a finding that we contextualize within the broader properties of ${\mathrm{YbAl}}_3$.

Flat bands, in which kinetic energy is quenched and quantum states become macroscopically degenerate, host a rich variety of correlated and topological phases, from unconventional superconductors to fractional Chern insulators. In Hermitian lattices, their formation mechanisms are now well understood, but whether such states persist, and acquire new features in non-Hermitian (NH) crystals, relevant to open and driven systems, has remained an open question. Here we show that the Hermitian principle for flat-band formation in bipartite lattices, based on a sublattice degeneracy mismatch, extends directly to the NH regime: whenever one sublattice hosts a momentum-independent eigenvalue with degeneracy exceeding that of its partner on the other sublattice, flat bands arise regardless of gain, loss, or complex couplings. Strikingly, at exceptional points, dispersive bands coalesce to form exceptional flat bands (EFBs) that persist beyond these singularities, exhibiting biorthogonal eigenmodes spanning both sublattices, with energies and lifetimes tunable via sublattice asymmetry and nonreciprocal couplings. This general framework unifies Hermitian and NH flat-band constructions, and reveals dispersionless states with no closed-system analog, as is the case of a bipartite lattice with imbalanced but constant sublattice chemical potentials. The proposed construction is applicable to synthetic platforms, from classical metamaterials, where flat bands can be directly emulated, to quantum-engineered systems such as photonic crystals and ultracold atom arrays, which should host correlated and topological phases emerging from such EFBs.

Identification of isolated Majorana zero modes (MZMs) is a key step toward the realization of fault-tolerant topological quantum computation. Here we show how the $T_1$-based noise magnetometry of a nitrogen-vacancy (NV) center qubit can reveal unique signatures of Majorana fermions bound to vacancies in a non-Abelian Kitaev quantum spin liquid (KQSL). The $1/T_1$ of the NV center is found to increase significantly when the working frequency of the NV center matches the energy difference between a MZM and a low-energy hybridized mode involving dangling Majorana fermions adjacent to vacancies. In experiments, this energy difference can be tuned by an external Zeeman field. Owing to the large excitation gap for flipping a local $Z_2$ gauge field, compared to the working frequency of NV centers, the $1/T_1$ spectrum is robust against other fluctuations in KQSLs at low temperatures. Our study presents a promising probe for identifying the non-Abelian phase in Kitaev materials.

The square-kagome lattice (SKL) antiferromagnet, composed of two-dimensional corner-sharing triangles, provides a prominent platform for studying frustrated magnetism. However, material realizations of the SKL remain scarce. Here, we report the single-crystal growth, structural characterization, magnetic and electric properties of ${\mathrm{KCu}}_7{\mathrm{TeO}}_4{\left({\mathrm{SO}}_4\right)}_5\mathrm{Cl}$, a nabokoite compound featuring a distorted and decorated SKL. Weak anomalies at temperature near 4 K are observed in both the magnetization and the specific heat data, indicating the onset of a magnetic transition. The observation of the ${}^{35}\mathrm{Cl}$ nuclear magnetic resonance line splits below 4.5 K further confirms the formation of the long-range-order antiferromagnetism. Magnetic susceptibility data reveal nearly isotropic Curie-Weiss temperatures ($\sim -145\mathrm{K}$) and $g$ factors ($\sim 2.4$) for both in-plane and out-of-plane magnetic fields. Moreover, we observe two successive ferroelectric transitions at $T_{\mathrm{FE}}1\sim 30\mathrm{K}$ and $T_{\mathrm{FE}}2\sim 27\mathrm{K}$, driven by inversion symmetry breaking, most likely associated with distortions in the ${\mathrm{Cu}2\mathrm{O}}_4{\mathrm{Cl}}_1$ pyramids and the adjacent ${\mathrm{SO}}_4$ tetrahedra. These results suggest that a three-dimensional model incorporating interlayer couplings via decorating Cu2 sites is essential for capturing the magnetic and electric behaviors in ${\mathrm{KCu}}_7{\mathrm{TeO}}_4{\left({\mathrm{SO}}_4\right)}_5\mathrm{Cl}$.