Magnetoelectronic coupling can be defined as cross-domain coupling between electronic and magnetic properties, where modulation in magnetic properties changes the electronic properties. In this Letter, explicit experimental evidence of magnetoelectronic coupling is presented, which is uncovered from the oscillatory Hall effect response in Hall measurement. The strain gradient in a MgO (1.8 nm)/$p$-Si ($\sim 400$ nm) freestanding sample leads to transfer of electrons ($\sim 5\times {10}^{18}\mathrm{c}{\mathrm{m}}^{-3}$) from valence to conduction band due to flexoelectronic charge separation in the $p$-Si layer. The resulting flexoelectronic polarization gives rise to the temporal magnetic moment from dynamical multiferroicity. The external magnetic field changes the net temporal magnetic moment, which causes modulations in charge carrier concentration and oscillatory Hall effect. The period of oscillatory Hall response is 1.12 T, which is attributed to the magnitude of the temporal magnetic moment. The discovery of the oscillatory Hall effect adds another member to the family of Hall effects.

Achieving thermal equilibrium in two-dimensional lattices of interacting nanomagnets has been a key issue on the route to study exotic phases in artificial frustrated magnets. We revisit this issue in one-dimensional artificial kagomé spin chains. Imaging arrested microstates resulting from a field demagnetization protocol and analyzing their pairwise spin correlations in real space, we unveil a nonequilibrated physics. Remarkably, this physics can be reformulated into an at-equilibrium one by rewriting the associated spin Hamiltonian in such a way that one of the coupling constants is quenched. We interpret this quenching mechanism as a kinetic hinderance occurring upon demagnetization, which induces the formation of local flux closure spin configurations that compete with those energetically favored by the magnetostatic interaction coupling the nanomagnets.

Here we systematically investigate the impact of the spin direction on the electronic and optical properties of transition metal phosphorus trichalcogenides ($M\mathrm{P}{X}_3, M=\mathrm{Mn}$, Ni, Fe; $X=\mathrm{S}$, Se) exhibiting various antiferromagnetic arrangements within the 2D limit. Our analysis based on the density functional theory and versatile formalism of Bethe-Salpeter equation reveals larger exciton binding energies for $M{\mathrm{PS}}_3$ (up to 1.1 eV in air) than $M{\mathrm{PSe}}_3$ (up to 0.8 eV in air), exceeding the values of transition metal dichalcogenides (TMDs). For the (Mn,$\mathrm{Fe})\mathrm{P}{X}_3$, we determine the optically active band-edge transitions, revealing that they are sensitive to in-plane magnetic order, irrespective of the type of chalcogen atom. We predict the anistropic effective masses and the type of linear polarization as important fingerprints for sensing the type of magnetic AFM arrangements. Furthermore, we identify the spin-orientation-dependent features such as the valley splitting, the effective mass of holes, and the exciton binding energy. In particular, we demonstrate that for $\mathrm{MnP}{X}_3$ ($X=\mathrm{S}$, Se), a pair of nonequivalent $K+$ and $K-$ points exists yielding the valley splittings that strongly depend on the direction of AFM aligned spins. Notably, for the out-of-plane direction of spins, two distinct peaks are expected to be visible below the absorption onset, whereas one peak should emerge for the in-plane configuration of spins. These spin-dependent features provide an insight into spin flop transitions of 2D materials. Finally, we propose a strategy for how the spin valley polarization can be realized in 2D AFM within a honeycomb lattice.

We investigate a model many-body system of spinless Fermi gas in two dimensions, where the bare two-body interaction is repulsive and takes the form of a soft-core disk potential. We obtain the zero-temperature phase diagram of this model by numerical functional renormalization group (FRG), which retains the effective interaction vertices in all channels to provide a detailed picture of how Cooper pairing emerges under the renormalization flow. The repulsion drives the system to a series of superfluid states with higher angular momentum pairing, for example in the $f$- and $h$-wave channels instead of the $p$-wave channel. This is in sharp contrast to the original Kohn-Luttinger mechanism where pairing of very large angular momenta and exponentially small transition temperature was predicted. We trace the stabilization and enhancement of $f$- and $h$-wave pairing back to the momentum dependence of the bare interaction. A perturbative calculation is carried out to show that while the second-order Kohn-Luttinger diagrams provide a qualitative understanding of the onsets of the various superfluid phases, they are unable to accurately capture the phase boundaries predicted by FRG. Our findings suggest that tuning the shape of the interaction potential offers a promising route to achieve stronger “pairing glue” and to realize nontrivial superfluid phases in repulsive Fermi gases beyond the scope of the original Kohn-Luttinger analysis.

We study the nonlinear response of conventional superconducting alloys with weak magnetic impurities to an external alternating electromagnetic field. In particular, we calculate a correction to the superconducting order parameter $|\delta {\mathrm{\Delta }}_{\mathrm{\Omega }}|exp\left(i\mathrm{\Omega }t\right)$ up to second order in the external vector potential and show that the frequency dependence of the order parameter amplitude has a characteristic resonant shape with a maximum at the frequency which is smaller than twice the magnitude of the pairing amplitude in equilibrium, $\mathrm{\Omega }<2\mathrm{\Delta }$, and at the same time exceeds the single-particle threshold energy. Our results suggest that in the presence of magnetic impurities the dynamics of the pairing amplitude in the collisionless regime will remain robust with respect to dissipative processes. We also evaluate the third harmonic contribution to the current as a function of the probe frequency and for various concentrations of magnetic impurities.

The discovery of unconventional superconductivity in the heavy-fermion material ${\mathrm{UTe}}_2$ has reinvigorated research of spin-triplet superconductivity. We perform a theoretical study of coupled two-component spin-triplet superconducting order parameters and their thermodynamic transitions into the superconducting state. With focus on the behavior of the temperature dependence of the specific heat capacity, we find that two-component time-reversal symmetry breaking superconducting order may feature vanishing or even negative secondary specific heat anomalies. The origin of this unusual specific heat behavior is tied to the nonunitarity of the composite order parameter. Additionally, we supply an analysis of the topological surface states associated with the different possible spin-triplet orders: single-component orders host Dirac Majorana surface states in addition to possible bulk nodes. A second component breaking time-reversal symmetry gaps these surface states producing chiral Majorana hinge modes. $\mathrm{DFT}+U$ band-structure calculations support that these topological phases are realized in ${\mathrm{UTe}}_2$ when introducing weak superconducting pairing. Our topological analysis suggests measurable signatures for surface-probe experiments to acquire further evidence of the superconducting pairing symmetry.

In various chaotic quantum many-body systems, the ground states show nontrivial athermal behavior despite the bulk states exhibiting thermalization. Such athermal states play a crucial role in quantum information theory and its applications. Moreover, any generic quantum many-body system in the Krylov basis is represented by a tridiagonal Lanczos Hamiltonian, which is analogous to the matrices from the $\beta \text{ensemble}$, a well-studied random-matrix model with level repulsion tunable via the parameter $\beta$. Motivated by this, here we focus on the localization properties of the ground and anti-ground states of the $\beta \text{ensemble}$. Both analytically and numerically we show that both the edge states demonstrate nonergodic (fractal) properties for $\beta \sim \mathcal{O}\left(1\right)$, while the typical bulk states are ergodic. Surprisingly, the fractal dimension of the edge states remains three times smaller than that of the bulk states irrespective of the global phase of the $\beta \text{ensemble}$. In addition to the fractal dimensions, we also consider the distribution of the localization centers of the spectral edge states, their mutual separation, as well as the spatial and correlation properties of the first excited states.

A field theory approach for the nonequilibrium relaxation dynamics in open systems at late times is developed. In the absence of conservation laws, all excitations are subject to dissipation. Nevertheless, ordered stationary states satisfy Goldstone's theorem. It implies a vanishing damping rate at small momenta, which in turn allows for competition between environment-induced dissipation and thermalization due to collisions. We derive the dynamic theory in the symmetry-broken phase of an $O\left(N\right)$-symmetric field theory based on an expansion of the two-particle irreducible (2PI) effective action to next-to-leading order in $1/N$ and highlight the analogies and differences to the corresponding theory for closed systems. A central result of this approach is the systematic derivation of an open-system Boltzmann equation, which takes a very different form from its closed-system counterpart due to the absence of well-defined quasiparticles. As a consequence of the general structure of its derivation, it applies to open, gapless field theories that satisfy certain testable conditions, which we identify here. Specifically for the $O\left(N\right)$ model, we use scaling analysis and numerical simulations to show that interactions are screened efficiently at small momenta and, therefore, the late-time evolution is effectively collisionless. This implies that fluctuations induced by a quench dissipate into the environment before they thermalize. Goldstone's theorem also constrains the dynamics far from equilibrium, which is used to show that the order parameter equilibrates more quickly for quenches preserving the $O\left(N\right)$ symmetry than those breaking it explicitly.

By using the high-level quantum chemistry method, we investigate the electronic and magnetic properties of Ni substituted polyacene structures as well as the laser-induced ultrafast spin dynamics and related spin logic gates. It is found that among the 61 lowest many-body states for each structure, the states with spin localized on a single magnetic atom mainly concentrate in the lower-energy region, while the states with spin localized on fused benzene rings are located in the higher-energy region. As the acene length becomes longer, the amount of states with spin localization on Ni atoms increases and the possibility of finding states with spin localization on benzene rings gets larger. Through the exploration of laser-induced spin dynamics in these structures, we find that different structures achieve different types of spin-transfer scenarios. Especially, although there exist several states with spin localization on different magnetic atoms for all the structures, the transfer between the two Ni atoms via one $\mathrm{\Lambda }$ process is only achieved in ${\mathrm{Ni}}_2({\mathrm{C}}_{18}{\mathrm{H}}_{10}$), ${\mathrm{Ni}}_2({\mathrm{C}}_{22}{\mathrm{H}}_{12}$), and ${\mathrm{Ni}}_2({\mathrm{C}}_{38}{\mathrm{H}}_{20}$). However, the indirect transfer between two Ni atoms is possible through several bridging $\mathrm{\Lambda }$ processes. Based on the achieved spin scenarios and by appropriately defining the bit information according to the spin localization and directions of the initial and final states, two types of ultrafast spin logic gates, i.e., SWAP and XOR, are constructed. The results obtained in these carbon-based magnetic structures provide valuable insights into their electronic structures and ultrafast spin manipulation and show their potential applications in future molecular spintronic devices and quantum computing.

Recently, Y. Sharma et al. [Adv. Sci. 9, 2203473 (2022)] claimed that thin films $(\sim 20 \mathrm{nm})$ of ${\mathrm{UO}}_2$ deposited on perovskite substrates exhibit strongly enhanced paramagnetism (called “induced ferromagnetism” by the authors). Moments of up to $3{\mu }_{\mathrm{B}}$/U atom were claimed in magnetic fields of 6 T. We have reproduced such films and, after characterization, have examined them with x-ray circular magnetic dichroism (XMCD) at the uranium M edges, a technique that is element specific. We do not confirm the published results. We find a small increase, as compared to the bulk, in the magnetic susceptibility of ${\mathrm{UO}}_2$ in such films, but the magnetization versus field curves, measured by XMCD, are linear with field and there is no indication of any ferromagnetism. The absence of any anomaly around 30 K (the antiferromagnetic ordering temperature of bulk ${\mathrm{UO}}_2$) in the XMCD signal suggests the films do not order magnetically.

The putative spin-triplet superconductor ${\mathrm{UTe}}_2$ exhibits multiple superconducting phases under applied pressure [Braithwaite et al., Commun. Phys. 2, 147 (2019)]. The clarification of pairing mechanisms and symmetries of gap functions are essentially important for understanding the multiple-phase diagram. Since the coexistence of ferromagnetic and antiferromagnetic spin fluctuations with Ising-like anisotropy is suggested from measurements of magnetic susceptibilities and neutron scattering measurements, it is expected that the interplay between these spin fluctuations plays a crucial role in the emergence of the multiple superconducting phases. Motivated by these observations, we examine the spin-fluctuation-mediated pairing mechanism, analyzing the linearized Eliashberg equations for an effective model of $f$-electron bands. It is found that the Ising-like ferromagnetic fluctuations stabilize spin-triplet pairings in either the $A_u$ or $B_{3u}$ states, whereas Ising-like antiferromagnetic fluctuations stabilize spin-triplet pairings in the $B_{1u}$ state. These results provide a plausible scenario elucidating the multiple superconducting phases under pressure.

We propose an effective model for the study of the interplay between correlation and topology by decorating the Kane-Mele model with a set of localized interacting orbitals hybridized to just one sublattice, breaking the inversion symmetry. We show that, in the time-reversal symmetric case, the interplay between interactions and hybridization extends the stability of the topological phase and depending on the driving mechanism very different behaviors are observed after the topological phase transition (TPT). We discuss the fate of the TPT in the presence of weak ferromagnetic order, by introducing a weak local magnetic field at the localized orbitals, which splits the two band inversion points. One of the platforms to apply this model to are ferrovalley compounds, which are characterized by two independent band inversion points. Understanding this family of materials is crucial for the development of the valleytronics. An alternative to spintronics, which uses valley polarization as opposed to spin degrees of freedom as the building block, promises great opportunities for the development of information storage.

Topological phase transitions are typically associated with the formation of gapless states. Spontaneous symmetry breaking can lead to a gap opening, thereby obliterating the topological nature of the system. Here we highlight a completely different destiny for a topological transition in the presence of interaction. Solving a Bernevig-Hughes-Zhang model with local interaction, we show that dynamical quantum fluctuations can lead to the opening of a gap without any symmetry breaking. As we vary the interaction and the bare mass of the model, the continuous gapless topological transition turns into a first-order one, associated with the presence of a massive Dirac fermion at the transition point, showing a Gross-Neveu critical behavior near the quantum critical endpoint. We identify the gap opening as a condensed matter analog of the Coleman-Weinberg mechanism of mass generation.

The heavy-fermion compound ${\mathrm{CeRhIn}}_5$ can be tuned through a quantum critical point, when In is partially replaced by Sn. In this way additional charge carriers are introduced and the antiferromagnetic order is gradually suppressed to zero temperature. Here we investigate the temperature-dependent optical properties of $\mathrm{CeRh}{\left({\mathrm{In}}_{1-x}{\mathrm{Sn}}_x\right)}_5$ single crystals for $x=4.4\%$, 6.9%, and 9.8%. With increasing Sn concentration the infrared conductivity reveals a clear enhancement of the $c\text{−}f$ hybridization strength. At low temperatures we observe a non-Fermi-liquid behavior in the frequency dependence of the scattering rate and effective mass up to approximately 50 meV in all three compounds. In addition, below a characteristic temperature $T^{*}\approx 10$ K, the temperature-dependent resistivity $\rho \left(T\right)$ follows a $logT$ behavior, typical for a non-Fermi-liquid. The temperature-dependent magnetization also exhibits anomalous behavior below $T^{*}$. Our investigation reveal that below $T^{*}$ the system shows a pronounced non-Fermi-liquid behavior and $T^{*}$ monotonically increases as the quantum critical point is approached.

The aluminum matrix composites (AMCs) reinforced with silicon carbide have attracted significant interest in several high-tech industries. In this work, we provide an insightful atomistic understanding of harmonizing mechanical and thermal properties of Al/SiC composites using superlattice models and ab initio machine-learning-potential calculations. Our calculations reveal the optimal value of SiC percentage as $25\%\sim 27\%$ in superlattice-type composites for combining high mechanical strength with ductility. With increasing the SiC percentage, the coefficients of thermal expansion decrease in the range of $0.5–2.5\times {10}^{-5}{\mathrm{K}}^{-1}$, while the lattice thermal conductivity increases in the range of $24–38$ W ${\mathrm{m}}^{-1}{\mathrm{K}}^{-1}$ at 300 K. These data will help tailor AMCs to the terms desired with the proposed ab initio based computational procedure.

Silicon hole quantum dots have been the subject of considerable attention thanks to their strong spin-orbit coupling enabling electrical control, a feature that has been demonstrated in recent experiments combined with the prospects for scalable fabrication in CMOS (complementary metal-oxide-semiconductor) foundries. The physics of silicon holes is qualitatively different from germanium holes and requires a separate theoretical description, since many aspects differ substantially: the effective masses, cubic symmetry terms, spin-orbit energy scales, magnetic field response, and the role of the split-off band and strain. In this work, we theoretically study the electrical control and coherence properties of silicon hole dots with different magnetic field orientations, using a combined analytical and numerical approach. We discuss possible experimental configurations required to obtain a sweet spot in the qubit Larmor frequency to optimize the electric dipole spin resonance (EDSR) Rabi time, the phonon relaxation time, and the dephasing due to random telegraph noise. Our main findings are as follows. (i) The in-plane $g$ factor is strongly influenced by the presence of the split-off band, as well as by any shear strain that is typically present in the sample. The $g$ factor is a nonmonotonic function of the top gate electric field, in agreement with recent experiments. This enables coherence sweet spots at specific values of the top gate field and specific magnetic field orientations. (ii) Even a small ellipticity (aspect ratios $\sim 1.2$) causes significant anisotropy in the in-plane $g$ factor, which can vary by $50\%–100\%$ as the magnetic field is rotated in the plane. This is again consistent with experimental observations. (iii) EDSR Rabi frequencies are comparable to Ge and the ratio between the relaxation time and the EDSR Rabi time $\sim {10}^5$. For an out-of-plane magnetic field the EDSR Rabi frequency is anisotropic with respect to the orientation of the driving electric field, varying by $\approx 20\%$ as the driving field is rotated in the plane. Our work aims to stimulate experiments by providing guidelines on optimizing configurations and geometries to achieve robust, fast, and long-lived hole spin qubits in silicon.

Silicon-emitting centers constitute promising candidates for quantum telecommunication technologies. Their operation depends on the fabrication of light-emitting defect centers such as the tri-interstitial Si complex, the W-center. In this paper the formation of Si tri-interstitial clusters after Ga ion beam bombardment on pure silicon substrates and a subsequent annealing stage is investigated using molecular dynamics simulations. This study aims to understand the dynamic formation process of W-centers after Ga irradiation and annealing in order to facilitate their creation using focused ion beam and annealing experimental systems. A tri-interstitial cluster identification method is proposed which considers the configuration of the clusters in the Si lattice in order to identify the defects which will act as candidates for the W-center. This method successfully identifies W-center defect candidates in an ideal system. The number of tri-interstitial clusters increases and spreads deeper into the Si for higher energies and their probability of generation increases until a limiting Ga fluence. Furthermore annealing can eliminate a lot of the unwanted defects maintaining at the same time the number of the tri-interstitial clusters, leading to isolated clusters with less distorted local environment.

The effect of the magnetic field on diffusion of the photogenerated holes was studied in a mesoscopic channel formed in a high-mobility GaAs quantum well where the electron-hole plasma reveals hydrodynamic properties. The reported results demonstrate that the magnetic field leads to a significant asymmetry of the diffusion profile, which depends on the direction of the magnetic field. According to the presented results, the observed asymmetry is due to the entrainment of holes by the electron Hall current. As a result, a magnetic-field-induced spatial separation of the diffusion of heavy and light holes was found. The valve effect, which controls the number of photogenerated light holes reaching the collection probes, is observed when the current through the collection probes is varied.

Janus materials have attracted much interest due to their intrinsic electric dipole moment and Rashba band splitting. We show that, by building bilayers of MoSeTe and WSeTe with different chalcogen atom sequences and different stacking patterns, one can modulate the net dipole moment strength and the Rashba effect, as well as the band alignment of the MoSeTe/WSeTe bilayer. Type-II band alignment is found which can be exploited to create long-lived interlayer excitons. Moreover, it is shown that the atomic sequence and stacking play pivotal roles in the interlayer distance of MoSeTe/WSeTe and thus its electronic structure and vibrational, especially low-frequency, characteristics. The long-range dispersion forces between atoms are treated with a conventional additive pairwise as well as a many-body dispersion method. It is shown that under the many-body dispersion method, more clear and rational thermodynamic trends of bilayer stacking are realized and interface distances are estimated more accurately. Vibrational spectra of the bilayers are calculated using first-principles phonon calculations and the fingerprints of monolayer attraction and repulsion are identified. An anticorrelation between distance and the shearing mode frequency of the rigid monolayers is demonstrated which agrees well with experimental findings. The results suggest that the judicious selection of the atomic sequence and stacking helps to widen the scope of the low-dimensional materials by adding or enhancing properties for specific applications, e.g., for spintronics or valleytronics devices.