In this paper, we report a detailed magnetotransport study on the conducting interface formed by juxtaposed ${\mathrm{LaVO}}_3$ (LVO) thin film on ${\mathrm{KTaO}}_3$ (KTO) substrate. Magnetoresistance (MR) shows a crossover from quadratic dependence to linear dependence at critical applied magnetic fields (${\mathrm{B}}^{*}$) for both in-plane (B $\parallel$ I) and out-of-plane (B $\perp$ I) configurations. The negative magnetoresistance and parabolic dependence of the ${\mathrm{B}}^{*}$ on temperature suggests the presence of linear band dispersion. In addition to linear magnetoresistance (LMR) at high magnetic fields, we have also observed weak antilocalization (WAL) cusp in magnetoresistance at low magnetic fields and temperatures for both in-plane and out-of-plane field configurations. Maekawa-Fukuyama (MF) theory is used to analyze the WAL data, which indicates the presence of two conduction channels. Angle dependence of WAL analysis shows that the conducting channels are not restricted to two dimensions. Temperature-dependent study reveals the presence of electron-electron and electron-phonon scattering mechanisms. Our analysis suggests the presence of a quasi-two-dimensional electron gas with linear band dispersion at the interface of ${\mathrm{LaVO}}_3$ and ${\mathrm{KTaO}}_3$.

Motivated by the largely unexplored domain of multipolar ordered spin states in the Kitaev-Heisenberg (KH) systems we investigate the ground state dynamics of the spin-$\frac{1}{2}$ KH model, focusing on quadrupolar (QP) order in two-leg ladder and two-dimensional honeycomb lattice geometries. Employing exact diagonalization and density-matrix renormalization group methods, we analyze the QP order parameter and correlation functions. Our findings reveal a robust QP order across a wide range of the phase diagram, influenced by the interplay between Heisenberg and Kitaev interactions. Notably, we observe an enhancement of QP order near Kitaev quantum spin-liquid (QSL) phases, despite the absence of long-range spin-spin correlations. This highlights a complex relationship between QP order and QSLs, offering different insights into quantum magnetism in low-dimensional systems. Our findings provide a rational explanation for the observed nonlinear magnetic susceptibility in $\alpha \text{−}{\mathrm{RuCl}}_3$.

While the possibility of topological superconductivity (TSC) in hybrid heterostructures involving topologically nontrivial band structure and superconductors has been proposed, the realization of TSC in a single stoichiometric material is most desired for fundamental experimental investigation of TSC and its device applications. Bulk measurements on ${\mathrm{YRuB}}_2$ detect a single superconducting gap of $\sim 1$ meV. This is supported by our electronic structure calculations, which also reveal the existence of topological surface states in the system. We performed surface-sensitive Andreev reflection spectroscopy on ${\mathrm{YRuB}}_2$ and detected the bulk superconducting gap as well as another superconducting gap of $\sim 0.5$ meV. From our analysis of electronic structure, we show that the smaller gap is formed in the topological surface states in ${\mathrm{YRuB}}_2$ due to the proximity of the bulk superconducting condensate. Thus, in agreement with the past theoretical predictions, we present ${\mathrm{YRuB}}_2$ as a unique system that hosts superconducting topological surface states.

Brucite $\left[\mathrm{Mg}{\left(\mathrm{OH}\right)}_2\right]$ is a mineral of great interest owing to its various applications and roles in geological processes. Its structure, behavior under different conditions, and unique properties have been the subject of numerous studies and persistent debate. As a stable hydrous phase in subduction zones, its elastic anisotropy can significantly contribute to the seismological properties of these regions. We performed ab initio calculations to investigate brucite's stability, elasticity, and acoustic velocities. We tested several exchange-correlation functionals and managed to obtain stable phonons for the $P\overline{3}$ phase with $r^2\text{SCAN}$ at all relevant pressures up to the mantle transition zone. We show that $r^2\text{SCAN}$ performs very well in brucite, reproducing the experimental equation of state and several key structure parameters related to hydrogen positions. The room-temperature elasticity results in $P\overline{3}$ reproduces the experimental results at ambient pressure. These results, together with the stable phonon dispersion of $P\overline{3}$ at all relevant pressures, indicate $P\overline{3}$ is the stable candidate phase not only at elevated pressures but also at ambient conditions. The success of $r^2\text{SCAN}$ in brucite suggests this functional should be suitable for other challenging layer-structured minerals, e.g., serpentines, of great geophysical significance.

Experiments carried out with the use of ultrasonic technique in doped crystals have established three mechanisms of relaxation of the Jahn-Teller subsystem at low temperatures. All of them have a quantum nature. The Debye relaxation function $f_D=1/(1+i\omega \tau )$ is changed due to the temperature-dependent relaxation time $\tau \left(T\right)$ provided the frequency $\omega$ is fixed. The dependence of $\tau \left(T\right)$ derived in an experiment on dissipation or/and dispersion of an ultrasonic wave makes it possible to obtain the temperature dependence of $f_D\left(T\right)$. As a consequence of quantum nature of the relaxation mechanisms, the dependence of $\tau \left(T\right)$ at low temperatures is an immanent characteristic of the system of Jahn-Teller complexes in a given matrix. Therefore graphical representations of $-\mathrm{Im}{f}_D\left(T\right)$ and $-\mathrm{Im}{f}_D\left(T\right)/T$ can serve as fingerprints of a certain Jahn-Teller complex.

Chiral magnetic states in two-dimensional (2D) layered noncentrosymmetric magnets, which are promising advanced spintronic materials, are usually attributed to Dzyaloshinskii–Moriya interactions (DMIs). However, the role of underlying higher-order spin couplings in determining the properties of chiral spin textures has been much less studied. In this work, taking the lithium-decorated monolayer ${\mathrm{CrTe}}_2$ (monolayer ${\mathrm{LiCrTe}}_2$) as an example, we develop a first-principles-based comprehensive spin model constructed by using the symmetry-adapted cluster expansion method. Based on this spin model, we identify the ground state of monolayer ${\mathrm{LiCrTe}}_2$ as a chiral spin spiral state, which can further assemble macroscopic chiral labyrinth domains under zero-field conditions as well as evolve into skyrmions under a finite magnetic field. Moreover, higher-order biquadratic and three-site interactions are identified to be responsible for modulating both the size and the field stability of the spin spiral state. Our study sheds light on complex magnetic couplings in 2D magnets.

${\mathrm{Mn}}_3\mathrm{Sn}$ has garnered significant attention due to its kagome lattice, ${120}^{\circ }$ noncollinear antiferromagnetic order, and substantial anomalous Hall effect. In this study, we comprehensively explore intrinsic and extrinsic contributions to anomalous Hall, anomalous Nernst, and anomalous thermal Hall effects, employing first-principles calculations and group theory analysis. Comparative analysis between our theoretical results and available experimental data underscores the predominance of the intrinsic mechanism in shaping anomalous transport properties at low temperatures. Specifically, Weyl fermions are identified as the primary contributors to intrinsic anomalous Hall conductivity. The significance of extrinsic mechanisms becomes evident at high temperatures, especially when the longitudinal charge conductivity falls into the dirty regime, where the side jump mechanism plays a vital role. Extrinsic contributions to anomalous transport properties are primarily influenced by the electronic states residing at the Fermi surfaces. Furthermore, anomalous transport properties exhibit periodic variations when subjected to spin rotations within the kagome plane, achievable by applying an external magnetic field. Our findings advance the understanding of anomalous transport phenomena in ${\mathrm{Mn}}_3\mathrm{Sn}$ and offer insights into potential applications of noncollinear antiferromagnetic materials in spintronics and spin caloritronics.

Frustrated triangular molecular magnets (MMs) with antiferromagnetic ground states (GSs) are an important class of magnetic systems with potential applications in quantum information processing. The twofold degenerate GS of these molecules, characterized by spin chirality, can be utilized to encode qubits for quantum computing. Furthermore, because of the lack of inversion symmetry in these molecules, an electric field couples directly states of opposite chirality, allowing a very efficient and fast control of the qubits. In this paper we present a theoretical method to calculate the spin-electric coupling for triangular MMs with effective local spins $s$ larger than 1/2, which is amenable to a first-principles implementation based on density functional theory (DFT). In contrast to MMs where the net magnetization at the magnetic atoms is ${\mu }_{\mathrm{B}}/2$ (${\mu }_{\mathrm{B}}$ is the Bohr magneton), the DFT treatment of frustrated triangular MMs with larger local magnetizations requires a fully noncollinear approach, which we have implemented in the nrlmol DFT code. As an example, we have used these methods to evaluate the spin-electric coupling for a spin $s=5/2\left\{{\mathrm{Fe}}_3\right\}$ triangular MM, where this effect has been observed experimentally for the first time quite recently. Our theoretical and computational methods will help elucidate and further guide ongoing experimental work in the field of quantum molecular spintronics.

Multiferroic material $\mathrm{C}{\mathrm{o}}_3\mathrm{Te}{\mathrm{O}}_6$ exhibits a sequence of structural and magnetic phase transitions, reflecting the interplay of lattice, orbit, and spin degrees of freedom. Here we report a different avenue to single-crystal growth and related morphology of $\mathrm{C}{\mathrm{o}}_3\mathrm{Te}{\mathrm{O}}_6$, and the compound is studied by magnetic susceptibility, specific heat, high-field magnetization, and electric polarization. We find that both magnetic susceptibility and specific heat in $\mathrm{C}{\mathrm{o}}_3\mathrm{Te}{\mathrm{O}}_6$ develop antiferromagnetic ordering $\sim 26\mathrm{K}$ and a first-order phase transition $\sim 18\mathrm{K}$. The emergence of an increase of magnetic moment in magnetic susceptibility is compatible with the anomaly in specific heat for $H\parallel b\text{—}\mathrm{we}$ suppose that is ascribed to the orbital physics because of the degenerate state of $t_{2\mathrm{g}}$ in $\mathrm{C}{\mathrm{o}}^{2+}$ ions. Low-field magnetization shows complex magnetic transitions and strong anisotropy in the system. Two spin flop transitions have been observed in high-field magnetization curve when magnetic field up to 55 T is applied along the $b$ axis. The changes of electric polarization are compatible with the magnetic transitions in magnetization. Those results reveal that the complex transitions arise from the competing interactions among spin, lattice, orbit, and external magnetic field.

The evolution of the vortex glass (VG) phase transition and vortex creep with decreasing film thickness is studied in ultrathin, polycrystalline niobium films with thickness in the range 7.4 to 44 nm, using current-voltage characteristics measurements in perpendicular magnetic field. Standard methods, including scaling laws, allow us to identify VG transition in the thickest film, while in thinner films creep produces large uncertainty in the putative VG transition temperature and scaling exponents. Using strong pinning theory we perform analysis of the creep and extract the dependence of the activation energy for vortex pinning on temperature, magnetic field, and film thickness. This analysis provides more information on vortex dynamics than the standard evaluation of critical current density. The results reveal two distinct regimes of pinning, which we propose to identify with $\delta l$ or $\delta T_c$ types of pinning (due to spacial fluctuation of mean free path $l$ or spacial fluctuation of superconducting transition temperature $T_c$, respectively). In the thickest film $\delta l$ pinning is observed, but with the decrease of film thickness the second pinning regime appears and becomes dominant in the thinnest film. We link these pinning regimes with the structural disorder due to grain boundaries, which produce charge carrier scattering in the thickest film but with decreasing film thickness gradually evolve into amorphous inclusions, producing fluctuations in the $T_c$.

Thermoelectric materials facilitate the mutual conversion of thermal energy and electric energy, representing environmentally friendly candidates for power generation. Consequently, there is significant interest in two-dimensional materials due to their potential for achieving superior thermoelectric performance when compared to their bulk counterparts. However, theoretical overestimations are prevalent for many of them, which originates from the fact that most theoretical studies have utilized a constant relaxation time within the framework of a single-mode deformation potential theory (DPT). In this work, we take monolayer $\mathrm{In}{\mathrm{P}}_3$ as an example to systematically revisit its thermoelectric transport by using parameter-free ab initio calculations combined with the Boltzmann transport equation. It is found that the scatterings from longitudinal acoustic phonons to charge carriers are not the most influential ones in monolayer $\mathrm{In}{\mathrm{P}}_3$, manifesting that the scattering rates are significantly underestimated within the crude approximation of single-mode DPT. By considering the state-dependent electron-phonon scattering rates, the monolayer $\mathrm{In}{\mathrm{P}}_3$ is found to have room-temperature maximum $\mathit{ZT}$ values of 0.37 and 0.18 for $n$- and $p$-type doping, respectively, which are one order of magnitude smaller than those predicted using a constant scattering rate from single-mode DPT. We demonstrate that conventional methods like single-mode DPT do not adequately describe the thermoelectric properties of monolayer $\mathrm{In}{\mathrm{P}}_3$. To calculate the thermoelectric transport of monolayer $\mathrm{In}{\mathrm{P}}_3$ properly, one needs to consider the scatterings from all phonons. We not only uncover the underlying mechanisms governing thermoelectric transport, but also offer a paradigm approach to accurately predict the thermoelectric transport with less computation cost.

An increase in spin imbalance induced by magnetic sublattice disorder within rare-earth (RE) metals can in turn increase the exchange bias coupling at the interfaces of RE–RE multilayers below the temperature of conical phases. In this work we have regulated the sublattice disorder by using different monolayers (MLs) of Ho within two highly textured multilayers Ho/Er comprising ${\mathrm{ML}}_{\mathrm{Ho}}=7$ and 29 while keeping ${\mathrm{ML}}_{\mathrm{Er}}=21$. For ${\mathrm{ML}}_{\mathrm{Ho}}=29$, the spin spiral constituting a fraction of the whole stack is expected to decrease the surface area–to–volume ratio and help in the profoundness of the conical phase, thereby contributing to the consequent increase in sublattice disorder. For ${\mathrm{ML}}_{\mathrm{Ho}}=7$, due to its limited extension, the spin spiral is expected to remain truncated and allow a relatively lower disorder. The sample with ${\mathrm{ML}}_{\mathrm{Ho}}=29$ exhibits two temperature-dependent phase transitions of the spin configurations (conical and helical), whereas only a single phase (conical) is identified for the ${\mathrm{ML}}_{\mathrm{Ho}}=7$ sample. Furthermore, a significant shift in temperature for the characteristic peak related to the conical-to-helical phase is observed as compared to an insignificant shift that is related to the helical-to-paramagnetic phase as we decrease the number of Ho MLs from 29 to 7, which eventually reduces the accumulated magnetic repeat distance (10 MLs) by three times. Interestingly, a meager exchange bias field of up to –0.007 $\mathrm{kOe}\pm 0.001$ kOe for ${\mathrm{ML}}_{\mathrm{Ho}}=7$ is found to increase by threefold to –0.02 $\mathrm{kOe}\pm 0.005$ kOe for ${\mathrm{ML}}_{\mathrm{Ho}}=29$, accounting for the increased sublattice disorder in its conical phase. For ${\mathrm{ML}}_{\mathrm{Ho}}=29$, as we replace 21 MLs of Er with 30 MLs of a ferromagnet (CoFe), we find the usual double hysteresis loops and the coupling strength also increases further to 0.07 $\mathrm{kOe}\pm 0.01$ kOe. Thus, the increased exchange bias phenomenon below 20 K in Ho/Er multilayers for the ${\mathrm{ML}}_{\mathrm{Ho}}=29$ sample reflects a higher spin imbalance induced by the magnetic sublattice disorder within Ho.

In this work, the phenomenon of downward deviations from the Curie-Weiss law is found above the Curie temperature (329–458 K) in ${\mathrm{Ni}}_2\mathrm{MnSb}$ polycrystalline Heusler alloy, and it was confirmed by the change in inverse magnetic susceptibility under different magnetic fields that it is the Griffiths phase. This abnormal phenomenon can be attributed to short-range nanoferromagnetic clusters caused by local lattice distortion within the paramagnetic state. The ac magnetic susceptibility further showed characteristics of long-range disordered and short-range ordered glassy magnetic states in Griffiths phase range, where the magnetization intensity of the spin glass state has a frequency dependence. This work revealed the nature of the Griffiths phase in Heusler alloys and observed the characteristics of spin glass at high temperatures, providing experimental evidence and support for the study of high-temperature spintronics.

The bilayer structures consisting of ${\mathrm{Mn}}_3\mathrm{PtN}$ (5 nm)/CoFeB(3 nm) and ${\mathrm{Mn}}_3\mathrm{Pt}$(5 nm)/CoFeB(3 nm) were fabricated via magnetron sputtering to investigate the role of nitrogen on charge-to-spin conversion efficiency in the noncollinear antiferromagnets (AFMs). The crystal structure of ${\mathrm{Mn}}_3\mathrm{PtN}$ (MPN) without N is consistent with that of ${\mathrm{Mn}}_3\mathrm{Pt}$ (MP) with $L{1}_2$-ordered structure, which allows us to study the different charge-to-spin conversion efficiency for AFMs with and without N. The spin-torque ferromagnetic resonance and second-harmonic Hall measurements were performed for both samples. It was revealed that the spin Hall angle $\left({\theta }_{\mathrm{SH}}\right)$ of the MPN with spin polarization in the $y$ direction was observed to be ∼0.033, exceeding the corresponding value of MP (∼0.025), which was qualitatively supported by the first-principles calculation. These results led us to conclude that N plays a crucial role in stabilizing the noncolliear antiferromagnetic structure and creating an electronic state advantage for the enhanced ${\theta }_{\mathrm{SH}}$.

A comprehensive analysis of the impact of strain on spin-orbit coupling (SOC) in permalloy (Py, $\mathrm{N}{\mathrm{i}}_{80}\mathrm{F}{\mathrm{e}}_{20}$) thin films is presented. Utilizing a combination of ferromagnetic resonance (FMR) and x-ray magnetic circular dichroism (XMCD) techniques, we systematically evaluate the modifications in SOC as a function of applied strain. Our FMR data indicate a marked enhancement in Gilbert damping and an increase in the perpendicular magnetic anisotropy constant, suggesting that SOC strength intensifies with both compressive and tensile strains. XMCD results, in concert with first-principles calculations, elucidate the underlying mechanism: strain-induced lattice distortions substantially elevate the orbital moments within the Py films. This boost in the orbital moment is attributed to the strain's modulation of the orbital quenching effect, revealing a direct correlation between lattice strain and SOC enhancement. These insights not only deepen our understanding of SOC in ferromagnetic thin films but also have potential implications for the design of spintronic devices where controlling SOC is paramount.

We report on the generation of ultrafast spin currents through femtosecond laser excitation of epitaxial bilayer thin films comprising $\alpha \text{−}{\mathrm{Fe}}_2{\mathrm{O}}_3$ (an insulating antiferromagnet) and Pt (a heavy metal). The epitaxial thin films of $\alpha \text{−}{\mathrm{Fe}}_2{\mathrm{O}}_3$ were simultaneously grown in three distinct orientations, namely, R, A, and C planes, employing pulsed laser deposition. By using the R plane $\alpha \text{−}{\mathrm{Fe}}_2{\mathrm{O}}_3$, we demonstrate a substantial enhancement of the THz signal, nearly one order of magnitude greater compared to the A and C planes $\alpha \text{−}{\mathrm{Fe}}_2{\mathrm{O}}_3/\mathrm{Pt}$. We perform a detailed investigation into the sample azimuthal and laser polarization dependence of the THz emission. Our investigations establish that the sample azimuthal dependence of THz emission in the $\alpha \text{−}{\mathrm{Fe}}_2{\mathrm{O}}_3/\mathrm{Pt}$ system is linked to the spin domain distribution as well as the crystalline symmetry of the orientation of $\alpha \text{−}{\mathrm{Fe}}_2{\mathrm{O}}_3$. These results contribute significantly to understanding the ultrafast dynamics of spin currents in antiferromagnets.

We propose a method for realizing tunable higher-order topological superconductors (TSCs) by coupling class DIII TSCs with recently discovered altermagnets exhibiting nonrelativistic spin splitting. We exemplify our approach using $d$-wave spin splitting and demonstrate the emergence of inversion-protected Majorana zero modes (MZMs) localized at the corner of the system, i.e., Majorana corner modes. Critically, we show that manipulating the Néel vector of the altermagnets enables control over the MZM distribution. This constitutes a crucial step towards achieving non-Abelian braiding of MZMs, a key ingredient for fault-tolerant topological quantum computation. Finally, we discuss a physical system that implements our proposal.

We model an interacting quantum dot of electrons by a Hamiltonian with random and all-to-all single-particle hopping (of root-mean-square strength $t$) and two-particle interactions (of root-mean-square strength $J$). For $t\ll J$, such a model has a regime exhibiting the nonquasiparticle physics of the Sachdev-Ye-Kitaev (SYK) model at temperatures $E_{\mathrm{coh}}\ll T\ll J$, and that of a renormalized Fermi liquid at $T\ll E_{\mathrm{coh}}$, where $E_{\mathrm{coh}}=t^2/J$. Extending earlier work has computed the mean thermoelectric properties of such a dot weakly coupled to two external leads, we compute the sample-to-sample fluctuations in the conductance and thermopower of such a dot, and describe several distinct regimes. In all cases, the effect of the SYK interactions is to reduce the strength of the sample-to-sample fluctuations. We also find that in the regime where the mean transport coefficients are determined only by the value of $J$ at leading order, the sample-to-sample fluctuations can be controlled by the influence of the smaller $t$.