We propose a tilt-assisted tunneling chirality Hall effect in the normal metal-superconductor (NS) junctions based on the time-reversal-broken type-I Weyl semimetals. It is found that the chirality-dependent skew reflection occurs at the NS interface due to the tilt of the Weyl cones, which is responsible for the nonzero transverse chirality Hall currents. Distinct from the Hall effect induced by the Berry curvature, we further illustrate that the transverse chirality current here is determined by the symmetry of the tilted Weyl Hamiltonian. Specifically, both the transverse chirality Hall current and the transverse charge Hall current may occur when the tilt of the Weyl cones break the mirror symmetry $\left(\mathcal{M}\right)$ of the Weyl Hamiltonian. However, a pure transverse chirality Hall current with zero net charge is present when the tilt breaks $\mathcal{M}$ symmetry but preserves the combined $\mathcal{MC}$ symmetry, where $\mathcal{C}$ represents the ${\mathbb{Z}}_2$ exchange symmetry.

Topological crystalline phases (TCPs) are topological states protected by spatial symmetries. A broad range of TCPs have been conventionally studied by formulating topological invariants (symmetry indicators) at invariant momenta in the Brillouin zone, which leaves open the question of their stability in the absence of translational invariance. In this work, we show that robust basis-independent topological invariants can be generically constructed for TCPs using projected symmetry operators. Remarkably, we show that the real-space topological markers of these invariants are exponentially localized to the fixed points of the spatial symmetry. As a result, this real-space structure protects them against the presence of impurities that are located away from the fixed points and also sufficiently slowly varying disorder potentials. By considering all possible symmetry centers in a crystalline system we can generate a mesh of real-space topological markers that can provide a local topological distinction for TCPs. We illustrate the robustness of this mesh of invariants with one- and two-dimensional TCPs protected by inversion, rotational, and mirror symmetries. Finally, we find that the boundary modes of these TCPs can also exhibit robust topological invariants with localized markers on the edges. We illustrate this with the gapless Majorana boundary modes of mirror-symmetric topological superconductors, and relate their integer topological edge invariant with a quantized effective edge polarization.

We describe theoretically the spin Nernst effect for electrons tunneling to a quantum dot from a quantum wire with the heat flowing along it. Such a tunneling spin Nernst effect is shown to take place due to the spin-dependent electron tunneling produced by the spin-orbit coupling. The Coulomb interaction of electrons in the quantum dot is taken into account using nonequilibrium Green's functions and is shown to increase significantly the accumulated spin in a single quantum dot. The largest possible degree of spin polarization is discussed.

We study critical properties of the entanglement and charge-sharpening measurement-induced phase transitions in a nonunitary quantum circuit evolving with a U(1) conserved charge. Our numerical estimation of the critical properties of the entanglement transition at finite system sizes appears distinct from the generic nonconserving case and percolation. We provide two possible interpretations of this observation: (a) these two transitions occur at different measurement rates in the thermodynamic limit, but at finite system sizes their critical fans overlap and the critical exponents we probed here show a combination of both criticalities. Nonetheless, the multifractal properties of the entanglement transition remain distinct from the generic case without any symmetry, indicating a unique universality class due to the U(1) symmetry. (b) These two transitions occur at the same measurement rate at any lengthscale. Within this interpretation, our estimation of all the critical exponents is sharply different from the nonconserving case, again confirming the presence of a new universality class due to U(1) symmetry. We compute entanglement critical exponents and correlation functions via various ancilla measures, we use a transfer matrix for multifractality, and we compute correlators associated with charge sharpening to explain these findings. Through these correlators, we also find evidence consistent with the charge-sharpening transition being of the Berezinskii-Kosterlitz-Thouless type (including the predicted “jump” in stiffness), which simultaneously argues for a broad critical fan for this transition. As a result, attempts to measure critical properties in this finite-size system will see anomalously large exponents predicted by our numerical analysis.

Sliding bilayers are systems that exploit the possibility of two relatively translating monolayers along a specific direction in real space, such that different stackings could be implemented in the process. This simple approach allows for manipulating the electronic properties of layered materials similarly as in twisted multilayers. In this work, we study the sliding of bilayers composed of one type of monolayer with spatial symmetry described by space group $P\overline{3}1m$. Using a minimal tight-binding model along with symmetry analysis, we propose two effects that arise in a specific sliding direction. First, we demonstrate sliding-induced control of the band gap magnitude, which produces a metal-insulator transition. In addition, we discuss the potential to achieve a topological adiabatic charge pump for cyclic sliding. For each effect, we also present material implementations using first-principles calculations. Bilayer GaS is selected for the metal-insulator transition and bilayer transition metal dichalcogenide ${\mathrm{ZrS}}_2$ is found to display the topological pump effect. Both realizations show good agreement with the predictions of the model.

Disorder is ubiquitous in any quantum many-body system and is usually considered to be an obstacle to the elucidation of the underlying physics of complex systems, but its presence can often introduce exotic phases of matter that cannot generally be realized in a clean system. We report here a detailed experimental and theoretical study of the magnetic properties of the highly disordered material ${\mathrm{Sr}}_3{\mathrm{CuNb}}_2{\mathrm{O}}_9$, which exhibits random site mixing between Cu and Nb. The magnetic moments $\left({\mathrm{Cu}}^{2+}\right)$ are arranged in a quasicubic (three-dimensional) manner, leading to a high degree of frustration with a Curie-Weiss temperature ${\theta }_{\mathrm{CW}}$ of about $-60$ K without any long-range magnetic ordering down to 466 mK. These observations suggest that ${\mathrm{Sr}}_3{\mathrm{CuNb}}_2{\mathrm{O}}_9$ is a candidate for a quantum spin liquid (QSL). More interestingly, the susceptibility $(\chi =M/{\mu }_{0}H)$ and $C_m/T$ ($C_m$ is the magnetic part of the heat capacity) follow a power-law behavior with decreasing temperature. In addition, $M(T,{\mu }_{0}H)$ and $C_m(T,{\mu }_{0}H)/T$ show scaling relationships over a wide range of temperatures and fields. This unusual behavior with respect to the conventional behavior of a QSL can be discussed qualitatively as the coexistence of a disorder-induced random spin-singlet (RSS) state and a QSL state. A quantitative description is given by numerical calculations considering a power-law probability distribution $P\left(J\right)\propto J^{-\gamma }$ ($J$ is the exchange interaction) of random spin singlets. The parameters extracted from the numerical calculations are in excellent agreement with the experimental data. Furthermore, the analytical results are also consistent with the power-law and scaling behavior of $\chi$ and $C_m(T,{\mu }_{0}H)/T$ as a whole. Thus, our comprehensive experimental and theoretical analysis provides evidence of the stabilization of the RSS state in a three-dimensional lattice.

The XY model is a valuable tool for analyzing spin systems. While the two-dimensional (2D) classical XY model and its variations that only consider spin interactions have been extensively studied, limited exploration has been conducted on the 2D XY model with orientation-position coupled (OPC) interactions. In the present study, we extend the 2D classical XY model by making the exchange energy dependent on the spin position; this model is referred to as the 2D compressible XY (CXY) model. Compared to the 2D classical XY model, we find that the OPC interaction enhances the stability of the orientational structure of the system. The deformation induced effects on the rotational degrees of freedom of the system indicates that the increase in the stretching deformation enhances the orientational order of spins. Furthermore, the coupling between orientation and position is demonstrated by calculating the joint probability distribution of spin orientation and position fluctuations. This study advances comprehension of spin systems' elasticity and provides new ideas for controlling the stability of the orientational order of spin systems.

Chiral phonons composed of circular atomic motion possess a tiny magnetic moment as a result of the small $g$ factor of ions. The couplings with the spin and orbit of electrons could entail a large magnetic moment. In this paper, we explore the possibility of an emergent phonon magnetic moment due to coupling with magnons in a hexagonal lattice. The magnetic moment of the phonon results from the mixture of magnon composition in the nonresonant coupling condition. Only one of the optical phonons gains a magnetic moment in the ferromagnetic case, while both phonon modes acquire a magnetic moment in the antiferromagnetic case. The magnon-induced magnetic moment of the phonon is proportional to the square of the magnon-phonon coupling strength. We also studied the case of nonequal atomic masses on sublattices which entails different magnetic moments of the two phonon modes.

We study two-dimensional $d$-wave altermagnetic metals, taking into account the presence of substrate-induced Rashba spin-orbit coupling. We consider the altermagnet band structure using a 2D band Hamiltonian near the $\mathrm{\Gamma }$ point under external magnetic field. It is shown that time-reversal-symmetry breaking due to altermagnetism, together with Rashba coupling and external magnetic field, can result in nontrivial band topology. The topological phases can be tuned by magnetic field strength and directions, and are classified by their Chern numbers. Furthermore, we investigate the charge response by computing the full optical conductivity tensor with and without magnetic field. In particular, we focus on magneto-optical responses, which are the finite-frequency analog of the Berry curvature-induced anomalous Hall conductivity. Finally, using experimentally realistic parameters for ${\mathrm{RuO}}_2$, we estimate the Faraday angle in the absence of magnetic fields.

In the doped topological insulator ${\mathrm{Sr}}_x{\mathrm{Bi}}_2{\mathrm{Se}}_3$, a pronounced in-plane twofold symmetry is observed in electronic properties below the superconducting transition temperature $T_c\sim 3\mathrm{K}$, despite the threefold symmetry of the observed $R\overline{3}m$ space group. The axis of twofold symmetry is nominally pinned to one of three rotationally equivalent crystallographic directions and crystallographic strain has been proposed to be the origin of this pinning. We carried out multimodal synchrotron diffraction and resistivity measurements down to $\sim 0.68\mathrm{K}$ and in magnetic fields up to 45 kG on a single crystal of ${\mathrm{Sr}}_x{\mathrm{Bi}}_2{\mathrm{Se}}_3$ to probe the effect of superconductivity on the crystallographic distortion. Our results indicate that there is no in-plane crystallographic distortion at the level of $1\times {10}^{-5}$ associated with the superconducting transition. These results further support the model that the large twofold in-plane anisotropy of superconducting properties of ${\mathrm{Sr}}_x{\mathrm{Bi}}_2{\mathrm{Se}}_3$ is not structural in origin, but electronic, namely, it is caused by a nematic superconducting order parameter of $E_u$ symmetry.

We introduce and study a realistic model for superconductivity in twisted bilayer ${\mathrm{WSe}}_2$, where electron pairing arises from spin-valley fluctuations in the weak-coupling regime. Our model comprises both the full continuum model moiré band structure and a short-ranged repulsive interaction. By calculating the spin-valley susceptibility, we identify a significant enhancement of the spin-valley fluctuations near half filling of the topmost moiré band. We then analyze the dominant Kohn-Luttinger pairing instabilities due to these spin-valley fluctuations and show that the leading instability corresponds to a two-component order parameter, which can give rise to nematic, chiral, and topological superconductivity. As our findings are asymptotically exact for small interaction strengths, they provide a viable starting point for future studies of superconductivity in twisted transition metal dichalcogenide bilayers.

We use high-resolution angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) to investigate the electronic structure of the charge density wave (CDW) system ${\mathrm{LaSb}}_2$. This compound is among an interesting group of materials that manifests both a CDW transition and lower temperature superconductivity. We find the DFT calculations to be in good agreement with our ARPES data. The Fermi surface of ${\mathrm{LaSb}}_2$ consists of two small hole pockets close to $\mathrm{\Gamma }$ and four larger pockets near the Brillouin zone boundary. The key features of the Fermi surface do not vary significantly with temperature. A saddle point is present at $-0.19\mathrm{eV}$ below the Fermi level at $\mathrm{\Gamma }$. Saddle points in the band structure have more pronounced effects on materials properties when they are located closer to the Fermi level, making doped ${\mathrm{LaSb}}_2$ compounds a potential interesting subject of future research. Multiple peaks are present in the generalized, electronic susceptibility calculations, indicating the presence of three possible nesting vectors. We were not able to detect any signatures of the CDW transition at 355 K down to the lowest temperature of 7 K, pointing to the subtle nature of this transition. This is unusual, given that such a high transition temperature is expected to be associated with the presence of a large CDW gap. This is confirmed through investigation of the Fermi surface and through analysis of momentum distribution curves. It is possible that changes are subtle and occur below current sensitivity of our measurements.

Defects in semiconductors, traditionally seen as detrimental to electronic device performance, have emerged as potential assets in quantum technologies due to their unique quantum properties. This paper investigates the microwave-induced current and the interaction between defects and quantum electron transport in GaN/AlGaN field-effect transistors near the pinch-off state and discusses the observed Fano resonances at low temperatures. We observe the resonance spectra and their dependence on gate voltage and magnetic fields. To explain the observed behavior, we construct the possible scenario as a Fano interferometer with finite width. Our findings reveal the potential of semiconductor defects to contribute to the development of quantum information processing, providing their role to key components in next-generation quantum devices.

A study of curved graphene in the presence and absence of a real magnetic field is conducted to determine the magnetization and magnetic susceptibility. Utilizing a Dirac model, the Landau-level energy corrections are found. These results are compared with those obtained from a tight-binding model analysis, showing good agreement with the Dirac model. The obtained spectra are then used to calculate the free energy, magnetization, and magnetic susceptibility as functions of the external magnetic field and curvature. The resulting de Haas–van Alphen effect exhibits distinctive signatures due to the curvature of graphene, including a resonance effect when the pseudomagnetic and the real magnetic fields are equal. Considering that curvature induces effective pseudomagnetic fields, a mechanical effect stemming from an electronic contribution is found, resulting in a pseudo de Haas–van Alphen effect without needing an external magnetic field. This effect is associated with oscillating (electronic) forces opposing deformations. These forces, divergent in flat graphene, suggest that graphene (without a substrate) attains mechanical equilibrium through local corrugations. These mechanical deformations prevent the theoretically calculated pristine graphene's diamagnetic divergence at low temperatures, indicating that corrugations produce a finite, experimentally measurable magnetic susceptibility. The divergent susceptibility becomes apparent only when such corrugations are removed using various strategies.

In the original article a mistake in the methodology led to an incorrect prediction of exciton delocalization below a critical exciton density. This unrealistic delocalized exciton state yielded a sizable domain-wall photovoltage. When done correctly, the simulations yield self-trapped (localized) excitons at all considered exciton densities, without any evidence for a transition to a delocalized exciton. This realistic self-trapped exciton state yields only a negligible domain-wall photovoltage. The original conclusion that ferroelectric domain walls could be responsible for the measured photovoltage if carrier lifetime and diffusion length are higher than expected is incorrect. Correct is: The domain-wall photovoltage in ${\mathrm{BiFeO}}_3$ is much too small to explain the measured photovoltage. The original analysis is meaningful for ferroelectrics without carrier self-trapping, not for ${\mathrm{BiFeO}}_3$.