Chiral crystals have a noncentrosymmetric unit cell and can manifest spin-orbit coupling (SOC)-induced band splitting, even in the absence of an atomic magnetic moment. We examine the particular case of Strukturbericht B20 compounds, with AlPt as representative material, by means of first-principles electronic structure calculations. We show how nonzero, but punctually compensated $\mathit{k}$ textures for both the spin and the orbital magnetic moment, emerge as a function of the lattice geometry, SOC, and in dependence on finite temperature. An applied electric field perturbation is shown to set up a bulk Edelstein effect in terms of both spin and orbital magnetic moment.

In this work, we extend the dual triply irreducible local expansion (D-TRILEX) approach for correlated electronic systems by introducing a cluster reference system for the diagrammatic expansion. This framework allows us to consistently combine the exact treatment of short-range correlation effects within the cluster with an efficient diagrammatic description of the long-range charge and spin collective fluctuations beyond the cluster. We demonstrate the effectiveness of our approach by applying it to the one-dimensional nano-ring Hubbard model, where the low dimensionality enhances nonalocal correlations. Our results show that the cluster extension of D-TRILEX accurately reproduces the electronic self-energy at momenta corresponding to the Fermi energy, in good agreement with the reliable Hirsch-Fye quantum Monte Carlo solution of the problem. We further compare this method with the more computationally demanding parquet dynamical vertex approximation and find that our method yields substantially more accurate results at momenta associated with the Fermi surface. We show that the D-TRILEX diagrammatic extension drastically reduces the periodization ambiguity of cluster quantities when mapping back to the original lattice, compared to cluster dynamical mean-field theory (CDMFT). Furthermore, we identify the CDMFT impurity problem as the main source of the translational-symmetry breaking and propose a computational scheme for improving the starting point for the cluster-diagrammatic expansion.

We investigate the influence of magnon-magnon interactions on the nonlinear magnon spin Nernst effect in honeycomb antiferromagnets within the framework of semiclassical Boltzmann transport theory under the relaxation time approximation. To incorporate interaction effects, we examine both three-magnon and four-magnon processes using a combination of perturbative many-body Green's function and mean-field approximations. We compute the interactions-induced modification in the magnon band structure and assess its impact on the nonlinear spin transport. In the case of in-plane Dzyaloshinskii-Moriya interaction, three-magnon scattering processes lead to a nonreciprocal splitting of the magnon spectrum, which remains stable and amplifies the spin Nernst effect in the linear regime. Conversely, four-magnon interactions lead to thermal renormalization of the magnon spectrum, which tends to reduce the nonlinear spin Nernst response. Our findings highlight the crucial role of magnon-magnon scattering in shaping the nonlinear spin response magnetic systems.

We investigate fluctuations of electric and heat currents, along with their cross-correlations, in a two-channel charge Kondo circuit driven by either a voltage bias or a temperature gradient applied across the weak link. The ratios of voltage-driven electric/heat noise to the applied voltage $V$ exhibit oscillations with the gate voltage $N$, resembling the behavior of the thermoelectric coefficient $G_T$. In contrast, the ratios of temperature-driven electric/heat noise to the temperature difference $\mathrm{\Delta }T$ vary with $N$ in a manner analogous to the thermal coefficient $G_H$ or the electric conductance $G$. The mixed noise, which is defined as the correlation function between electric and heat currents, displays behavior opposite that of the above noises. The logarithmic temperature dependence of these noises signals non-Fermi-liquid behavior, while their oscillations with gate voltage reflect the roles of particle-hole and time-reversal symmetries in thermoelectric transport. Our results demonstrate that the fundamental relations linking voltage- and temperature-induced noises to thermoelectric transport across a tunnel junction persist beyond the Fermi-liquid paradigm.

We study global anomalies of nonlocal effective theories proposed to describe symmetry-preserving Luttinger surfaces, i.e., the momentum-space manifolds of Green's function zeros (GFZs) at zero energy, in strongly interacting fermionic systems. In particular, we focus on the simplest possible cases associated with a gapless Dirac zero, which is the counterpart of the gapless Dirac quasiparticle in weakly interacting systems. These theories may be derived by integrating out low-energy degrees of freedom that do not couple to the relevant gauge field. We discuss the global anomaly, the bulk-boundary correspondence, and the constraint on phases consistent with the anomaly, such as non-Fermi liquids and emergent gapless quasiparticles on Luttinger surfaces. Failing to avoid spontaneous symmetry breaking in the thermodynamical limit inevitably leads to unstable GFZs. We also provide some perspective on why the related nonlocal fermionic effective theory studied recently is not a suitable starting point for a symmetrically gapped phase.

We introduce an extended framework for the simultaneous gauging of modulated symmetries in $(d+1)$ dimensions, employing multiple gauge symmetry operators the corresponding gauging procedures of which must be carried out simultaneously. Simultaneous gauging can capture a broader class of dualities than sequential gauging, the latter corresponding to the conventional gauging applied in successive steps. In general, performing simultaneous gauging and conventional gauging in sequence constitutes the most general framework for gauging modulated symmetries. We further show that the associated duality transformations can be implemented via adaptive state preparation protocols. As a concrete example, we consider a dipole symmetry in $(2+1)\text{dimensions}$ and illustrate both the simultaneous gauging procedure and the adaptive preparation protocol. Interestingly, we find that the intermediate state of the simultaneous gauging/adaptive circuit corresponds to a symmetry-protected topological phase protected by the dipole bundle symmetry. Finally, we utilize the duality to analyze the phase diagram of the rank-2 toric code under transverse fields.

The heavy fermion compound ${\mathrm{CeRu}}_4{\mathrm{Sn}}_6$ was recently shown to exhibit a spontaneous nonlinear Hall effect, indicating its topological nature. This is consistent with the lack of inversion symmetry that allows for the existence of Weyl nodes. Here, we employ density functional theory combined with dynamical mean field theory, which is state of the art for strongly correlated materials, and study the topology of ${\mathrm{CeRu}}_4{\mathrm{Sn}}_6$. We find five inequivalent Weyl nodes of either type I or II, each having either 8 or 16 symmetry-related replicas. These Weyl nodes bridge the Kondo insulating gap, which is a direct but not an indirect gap. The Weyl points closest to the Fermi level are situated only 0.5 meV below it and have a very flat dispersion. Our ab initio results establish ${\mathrm{CeRu}}_4{\mathrm{Sn}}_6$ as a model system for investigating the interplay between strong electronic correlations and nontrivial topology. These findings provide a theoretical foundation for future studies of quantum transport and interaction-driven topological phases in heavy fermion systems.

Recently, two unusual features were theoretically predicted for the Raman response of out-of-plane phonons in magnetic two-dimensional materials hosting massive Dirac fermions. First, the phase difference between certain Raman tensor elements was found to be quantized to $\pm \pi /2$, sensitive only to the sign of the Dirac fermion mass. Second, a selection rule was identified in the Raman intensity under circularly polarized light, which generalizes the well-known optical valley selection rule. These predictions were based on a low-energy effective model in the continuum approximation. Here, we test the robustness of those results for more realistic theoretical approaches. First, we calculate the Raman tensor for an electronic tight-binding model on a honeycomb lattice with broken time-reversal and inversion symmetries. Second, we compute the Raman tensor from density-functional theory for a monolayer of ferromagnetic $2\mathrm{H}\text{−}{\mathrm{RuCl}}_2$. Both calculations corroborate the analytical results found in the continuum model, thereby theoretically confirming the peculiar behavior of the Raman tensor for two-dimensional massive Dirac fermion systems.

Recently, the non-Hermitian skin effect has attracted significant attention. In systems exhibiting this effect, the spectrum under the periodic boundary conditions and open boundary conditions are different, i.e., the spectrum is highly sensitive to the boundary conditions. However, most of present examples of such boundary sensitivity pertain to systems related to the non-Hermiticity, and the analogous phenomena in the spectrum of a purely Hermitian system is rare. In this work, inspired by the doubled-Hamiltonian method, we present a general construction of boundary-sensitive topological phases in Hermitian multileg ladders with chiral symmetry. Then we take a $p$-wave superconducting multileg ladder as an example. We find that both the Hermitian spectrum and the topological phase of this system are sensitive to the boundary conditions perpendicular to each leg, which persists even in the presence of an impurity chain or disorders. Our work provides a possible approach for engineering spectra and topological phases via manipulating boundary conditions in some artificial Hermitian systems.

Symmetry plays a vital role in determining properties of a system, and therefore, breaking the symmetry often gives rise to physical phenomena beyond the parent system. Here, we show that breaking rotational symmetry of an atomic collapse potential can induce intervalley scattering between states with different orbital angular momenta and result in an additional phase singularity around a supercritically charged vacancy in graphene. By using scanning tunneling microscopy, we directly detect transition of phase accumulation in the intervalley scattering from $4\pi$ outside the potential, contributed purely by pseudospin rotation, to $2\pi$ or $0\pi$ inside the potential, contributed by both the pseudospin rotation and nonzero angular momentum transfer. Moreover, in this study, we reveal that the anisotropic atomic collapse potential breaks the $C_3$ rotational symmetry of graphene and results in unexpected anisotropic interorbital angular momentum scatterings. Our observations establish a route to tune the quantum phase at atomic scale and highlight the role of breaking the symmetry in discovering emergent quantum phenomena in Dirac materials.

We present a detailed study of magnetization, resistivity, heat capacity, and x-ray and neutron powder diffraction measurements performed on single crystals of nonstoichiometric ${\mathrm{CeAuBi}}_2$, Au deficiency $18\%$, a strongly correlated antiferromagnet with Néel temperature $T_N=13.2$ K. Field-dependent magnetization measurements reveal a large magnetic anisotropy at low temperatures with an easy axis along the crystallographic $c$ axis, in which direction a spin-flop transition exhibits strong features in magnetization, specific heat, and resistivity at $H_c=75$ kOe. The constructed temperature-field phase diagram connects this transition to the suppression of magnetic order, which evolves from a second-order nature into a first-order transition that bifurcates at the spin-flop transition into three transitions below 1 K. The smoothed nature of the metamagnetic transitions in nonstoichiometric ${\mathrm{CeAuBi}}_2$ is well described by an Ising model with weak quenched disorder, suggesting that the presence of Au vacancies is sufficient to smear the complex metamagnetic behavior and tune the critical behavior of magnetic order.

Spin-orbit coupling in transition-metal oxides entangles lattice, charge, and spin degrees of freedom to generate unconventional magnetic states. In Sn-doped ${\mathrm{Ca}}_{\text{2}}{\mathrm{RuO}}_{\text{4}}$, compression of the ${\mathrm{RuO}}_6$ octahedra enhances the ${\mathrm{Ru}}^{4+}$-ordered moment and drives $a$-axis spin canting via Dzyaloshinskii-Moriya interactions from staggered octahedral tilts and rotations. Neutron diffraction, depolarization, and magnetization measurements reveal a canted component ($\alpha \approx 2.{92}^{\circ }$) together with a weak ferromagnetic response. These results demonstrate that tetragonal compression stabilizes an in-plane canted AFM state with enhanced moment, establishing it as an effective lever to engineer spin-orbit entangled magnetism in layered ruthenates.

Artificial spin ices (ASIs) provide a versatile platform to explore magnetic frustration and emergent phenomena. However, in kagome ASI, experimental access to the ground state remains elusive due to dynamical freezing. Here we demonstrate a deterministic and rewritable approach to attain the ground state using ultrafast, site-selective laser annealing. By engineering sublattice-dependent optical absorption through selective capping of the nanomagnets with Cr or utilizing different nanomagnet thicknesses, we achieve selective partial demagnetization and subsequent reversal of one nanomagnet sublattice under a subcoercive magnetic field, driving the system into the ground state in a single switching step. Magnetic force microscopy reveals nearly perfect long-range ordering, while heat-transfer simulations confirm the sublattice-selective excitation mechanism. This work establishes an ultrafast method to attain the kagome ASI ground state, which does not require a modification of the geometry of the ASI or the materials used for the individual nanomagnets. Beyond ground-state writing, this site-selective activation provides an important tool for controlling the magnetic states, which is important for applications such as reconfigurable magnonic crystals, neuromorphic computing and programmable nanomagnetic logic.

The quantitative description of the electrical resistivity of a magnetic material remains challenging to this day. Qualitatively, it is well understood that the temperature-induced lattice and spin disorder determines the temperature dependence of the resistivity. While prior publications reached good agreement with experiment in the so-called supercell or direct approach for nonmagnetic materials, where the spin-disorder contribution to the resistivity is negligible, an accurate, purely theoretical description of magnetic materials remains elusive. This shortcoming can be attributed to the missing accuracy in the description of the temperature-dependent spin disorder itself. In this work, we employ a joint approach from ab initio transport calculations and atomistic modeling of the temperature-dependent spin disorder. Using the example of $\alpha$-Fe, we demonstrate that including quantum-mechanical effects via a semiclassical local quantization of the Heisenberg model significantly improves the description of the spin-disorder component of the electrical resistivity. Compared to previous approaches, this model includes the description of magnetic short-range order effects, enabling us to study temperature effects around and above the Curie temperature, where prior mean-field theory-based approaches inevitably predicted a constant contribution.

Hydride superconductors under extreme pressure exhibit record-high critical temperatures as a result of their exceptionally strong electron-phonon coupling (EPC). To clarify how such strong EPC influences nonequilibrium carrier dynamics, ultrafast hot-electron relaxation in calcium hydrides ($\mathrm{Ca}{\mathrm{H}}_n, n=2$, 4, 6) was investigated using momentum-resolved first-principles quantum dynamics. A two-stage relaxation process was identified: an initial momentum relaxation, where phonons randomize electron momentum with little energy loss, followed by an energy relaxation dominated by optical phonon emission that transfers electronic energy into the lattice. With increasing EPC from semiconducting $P{6}_3/mmc-{\mathrm{CaH}}_2$ to superconducting $Im\overline{3}m-{\mathrm{CaH}}_6$, both processes were found to be markedly accelerated. In the superconducting phase, the energy relaxation was completed within several tens of femtoseconds, demonstrating ultrafast energy transfer from electrons to the lattice. A fundamental regularity is thus revealed: while stronger EPC enhances $T_{\mathrm{c}}$, it also governs an ultrafast channel for initial carrier thermalization and energy injection into the lattice following a perturbation. This defines a distinct early-stage microscopic pathway for energy redistribution in strongly coupled superconductors.

The ability to nondissipatively tune the Josephson coupling energy of Josephson junctions is a useful tool in frequency-tunable qubits. This is typically done by threading magnetic flux through two junctions connected in a loop, a geometry that exposes the qubit to magnetic environmental noise. In this paper, we show that by biasing a junction with supercurrent from a separate pair of superconducting leads coupled to the device, the Josephson energy can be tuned without the need for a flux loop. Our multiterminal device may enable the realization of a frequency-tunable qubit with greatly reduced susceptibility to flux noise.

Understanding the transport properties of quantum many-body systems is a central challenge in condensed matter and statistical physics. Theoretical studies usually rely on two main approaches: dynamics of linear-response functions in closed systems and boundary-driven dynamics governed by Markovian master equations for open systems. While the equivalence of their dynamical behavior has been explored in recent studies, a systematic comparison of the transport coefficients obtained from these two classes of approaches remains a largely open question. Here, we address this gap by comparing and contrasting the dc diffusion constant ${\mathcal{D}}_{\text{dc}}$ according to the two approaches, focusing on the specific example of magnetization transport in the spin-$1/2$ XXZ chain. Using exact numerical simulations for finite system sizes, we find (i) a clear mismatch between the two ${\mathcal{D}}_{\text{dc}}$ and (ii) a strong dependence of ${\mathcal{D}}_{\text{dc}}$ on the system-bath coupling strength for the open system, where neither (i) nor (ii) tend to vanish in the thermodynamic limit. These findings suggest limitations of the open-system approach to transport coefficients. To gain insight into the origin of (i) and (ii), we go beyond ${\mathcal{D}}_{\text{dc}}$ and analyze the full time dependence of the diffusion coefficient $D\left(t\right)$ in the open system. In this way, we find that both (i) and (ii) vanish up to a finite timescale. While this timescale gradually increases with system size and tends to be macroscopic in the thermodynamic limit, this increase is still slow compared to the increase of the time to reach the steady state, where (i) and (ii) do not vanish. This observation can be seen as a wrong, yet unavoidable order of limits of long times first and large system sizes afterward.