Altermagnets, a novel class of collinear magnets with momentum-dependent spin splitting and zero net magnetization, offer unique opportunities for tunable thermal transport. Here, we investigate the electronic thermal conductivity (ETC) in two-dimensional d-wave altermagnets, focusing on its anisotropy and responsiveness to external perturbations, such as electrostatic gating, circularly polarized light driving, and doping. Employing a semiclassical Boltzmann transport framework with relaxation-time approximation, we derive expressions for the ETC tensor integrated over the Floquet-renormalized quasiparticle spectrum. Our model incorporates Rashba spin–orbit coupling from perpendicular gating and Floquet engineering via high-frequency optical driving, which collectively modify the band structure, spin textures, and carrier velocities. Numerical evaluations reveal pronounced directional anisotropy in the ETC along principal crystallographic axes, with gating enhancing in-plane distortions and light driving enabling dynamic renormalization of the altermagnetic gap and Rashba parameters. These effects yield temperature-dependent thermal responses that deviate from the pristine phase of matter, positioning altermagnets as versatile platforms for thermospintronic devices and heat management without net magnetization.

The low-energy effective Hamiltonian of a cylindrical HgTe nanowire grown along the [001] crystallographic direction is constructed by using the perturbation theory. Both the anisotropic term and the bulk inversion asymmetry term of the Kane model are taken into account. Although the anisotropic term has converted the crossing between the $E_{1}$ and $H_{1}$ subbands into an anticrossing at $k_{z}R\!=\!0$, the gap-closing-and-reopening transition in the subband structure can still occur at finite wave vectors $k_{z}R\!\approx\!\pm0.24$ for critical nanowire radius $R\!\approx\!3.45$ nm. The bulk inversion asymmetry does not contribute to the low-energy effective Hamiltonian, i.e., there is no spin splitting in the $E_{1}$, $H_{1}$, and $H_{2}$ subbands for a [001] oriented cylindrical nanowire.

Altermagnets, due to spontaneous spin splitting induced by the breaking of the PT inversion symmetry, are now widely used in the design of novel antiferromagnetic (AFM) spintronic devices. Herein, we demonstrate symmetry breaking in AFM via slip and strain engineering, achieving a non-alter spin splitting compensated magnet. As a demo concept, a four-layer sliding strategy in GdI2 is put forward, enabling sliding-induced ferroelectric (FE) and magnetic switching. The FE polarization breaks PT symmetry, inducing spin-split band structures that drive AFM to ferromagnetic (FM) phase transformation or nonrelativistic spin-splitting (NRSS) AFM. The designed multiferroic tunnel junction demonstrates electric-field-controlled four-state resistance switching with low resistance area. The regulation effect of strain on the device's transport properties has also been simulated. The compressive strain enhances the crystal symmetry in the FE-FM phase, triggering an FM-NRSS-mediated AFM transition and boosting tunneling electromagnetic resistance, providing a novel strategy and mechanism for developing low-power, high-density memory devices.

Janus MoSSe has emerged as a promising 2D platform for photocatalytic water splitting owing to its intrinsic out-of-plane dipole, selective surface reactivity, and efficient charge separation. However, pristine MoSSe remains intrinsically limited for the oxygen evolution reaction (OER), which drives the need for structural, chemical, and interfacial engineering. In this perspective, we review recent progress in understanding how defect chemistry, transition-metal functionalization, doping, curvature, and van der Waals heterostructures alter dipole moments, band alignment, carrier lifetimes, and water adsorption energies-all key physical descriptors governing catalytic performance. An interesting picture emerges: MoSSe becomes an effective photocatalyst when paired with an OER-active partner that complements its strong HER-driving conduction band. Connecting it with 2D materials like WS2, black phosphorus, GaN, and AlN introduces the necessary valence-band depth and polarization to meet both redox requirements. The experimental MoSSe/GaN system supports the theoretical predictions and adds multifunctional Rashba-Dresselhaus spin splitting and magnetic-field-enhanced charge dynamics to the list of photocatalytic descriptors. Collectively, these insights lay out a design roadmap for engineering Janus-based heterostructures that optimize water splitting under visible light.

The bonding between a transition metal (TM) and carbon monoxide is found in many chemical complexes that are important in biological and catalytic processes. Density functional theory (DFT) methods have been widely used for many calculations; however, the validity of such calculations for complex spin state coupling induced by TM-CO bond formation remains unclear. Interestingly, binding between a 3d TM atom and carbon monoxide induces a spin state change, making it a good benchmark system for evaluating various functionals. There have been numerous studies evaluating the TM atom spin state splitting or spin state energy difference of CO-bound TM complexes. However, we did not find benchmark studies evaluating the potential energy surfaces of the TM-CO association for various spin states to determine the spin-state crossing point. In the present study, we calculated the 3d TM + CO association potential energy curve using various DFT functionals. For TM = Sc, Ti, Fe, Co, and Ni, we performed multireference calculations with multiple excited states to clarify the spin state crossing points. We found that hybrid functionals can give spin state crossing points within 0.15 Å of those obtained by multireference methods, and confirmed that accurate atomic spin splitting results in more accurate crossing point geometry. In addition, we found minimal basis set dependence for the association potential energy curve for B3LYP. To our surprise, this study showed that hybrid DFT functionals can describe spin crossing phenomena in the TM + CO association.

Hyperbolic altermagnets with high-fold spin splitting

Symmetry-driven spin splitting in altermagnets: an angle-resolved photoemission spectroscopy perspective.

Altermagnets (AMs) are unconventional collinear antiferromagnetic materials that have recently been discovered to exhibit nonrelativistic spin splittings despite their fully compensated magnetization. Leveraging the advantages of ferromagnets and conventional antiferromagnets, AMs offer great potential for high-density, high-frequency spintronic devices. Combining symmetry analysis and first-principles calculations, we show that such altermagnetic spin splittings exist locally in layered Ruddlesden-Popper oxides (e.g., Ca2MnO4 and La2NiO4) but are ultimately hidden when there are an even number of perovskite layers. We demonstrate that the local spin splitting can be made globally apparent via an electric field effect, which breaks inversion symmetry. Furthermore, we demonstrate the tunability of altermagnetic properties by oxygen stoichiometry engineering with equatorial oxygen vacancies enhancing the spin splitting. A large concentration of apical oxygen vacancies further drives an insulator-to-metal transition. Our work not only broadens the AM materials platforms but also provides strategies for tuning the electronic structure for antiferromagnetic spintronic applications.

The spin degree of freedom of charge carriers provides an effective way to expand the functionality of conventional electronic devices. In this work, based on density functional theory, we discover giant Rashba-type spin splitting with a remarkable Rashba coefficient of 2.85 eV Å in wafer-scale lead sulfide (PbS) thin films. As a matter of fact, single-crystal PbS has a rock salt crystal structure, which is centrosymmetric. However, structural inversion symmetry breaking at the surface of PbS enhances Rashba splitting at the M-point of the Brillouin zone due to spin–orbit coupling. The electron spin and momentum are tightly locked, thus the spin current can be effectively converted into charge current under circularly polarized light excitation. Consequently, an obvious circular photogalvanic effect (CPGE) voltage was observed in the Rashba-type spin–orbit interaction system, as identified by electrical measurements of the CPGE in PbS thin films. This work demonstrates the feasibility of achieving strong spin–orbit coupling in centrosymmetric materials, providing a compelling platform for developing low-cost spintronic devices.

Abstract The ability to engineer molecular junctions with adjustable spin and thermoelectric properties is at the core of developing high-performance nanoscale devices. We explore endohedral fullerenes M@C 80 (M = Fe, Co, Ni) connecting gold and graphene electrodes through DFT combined with the non-equilibrium Green's function method. The insertion of transition metals within the C 80 cage induces huge charge transfer, orbital hybridization, and spin splitting, which results in transmission spectra that are heavily modulated. Au-Fe@C 80 -Au possesses the highest spin polarization and partial unity transmission at the Fermi level and is therefore best suitable for spintronics applications. Gr-Co@C 80 -Gr achieves an ultrahigh thermoelectric figure of merit (ZT > 1000) due to sharp energy-dependent transmission characteristics and enhanced π-π coupling with graphene. Ni@C 80 displays broad conduction peaks optimal for energy-selective transport. A direct comparison of gold and graphene electrodes reveals that gold ensures strong and stable molecularelectrode coupling with higher conductance, whereas graphene offers superior energy filtering and enhanced Seebeck response.

Abstract In this work, we propose a series of novel two-dimensional (2D) Janus CrBZS 2 (Z = N, P, As) monolayers and systematically investigate their physical properties, including structural characteristics, mechanical behavior, piezoelectric (PIE) responses, electronic properties, and transport characteristics, using density functional theory calculations. Stability analyses indicate that these 2D materials possess robust crystal structures and are potentially synthesizable using conventional experimental methods. In their ground state, the CrBZS 2 monolayers are semiconductors with moderate band gaps. Zeeman-type spin splitting is observed when spin–orbit coupling is taken into account. The broken mirror symmetry in these materials induces both in-plane and out-of-plane PIE effects, with CrBAsS 2 exhibiting a particularly large out-of-plane response, reaching a d 31 coefficient of up to 0.50 pm V −1 . The intrinsic carrier mobility is governed by different scattering mechanisms depending on carrier type, carrier concentration, and material composition. Acoustic deformation potential (ADP) scattering is identified as the dominant mechanism determining total electron mobility, whereas ionized impurity, PIE, and ADP scattering can all play decisive roles in controlling total hole mobility, depending on the specific case.

ABSTRACT Although significant progress has been made in devising approaches to control magnetism and spin polarization in 2D multiferroic systems, ferroelasticity, widely recognized as a fundamental ferroic order, has received far less attention compared with ferroelectricity. In this work, we constructed a general tight‐binding (TB) model that provides a universal framework for describing the ferroelastic switching in 2D ferrimagnetic metals. Based on this model and first‐principles calculations combined with a swarm‐intelligence structure‐search strategy, we identified an example, monolayer Nb 2 CN, which simultaneously exhibits ferroelasticity, ferrimagnetism, and metallicity. Interestingly, the system can present a triply‐coupled ( S , M , ε ) switching—reversible local spin splitting ( S ), net magnetization ( M ), and ferroelastic strain ( ε ). These spin‐magnetic‐lattice couplings inevitably lead to sign reversals in anomalous transport responses such as the anomalous Hall and magneto‐optical effects. These findings not only reveal a novel magnetoelastic coupling mechanism for triply‐coupled control of magnetism and spin polarization in 2D materials but also provide a promising platform for designing multifunctional spintronic devices.

Exploiting the atomistic tight-binding theory with the sp-d exchange term, the electronic and magnetic characteristics of CdSe nanoparticles embedded with Mn, Fe and Co are determined as a function of external magnetic fields to realize the sp-d exchange interactions. The transition metal species and applied magnetic fields are powerful factors to manipulate the electronic and magnetic characteristics of doped CdSe nanoparticles. With growing applied fields, the energies of spin splitting, Zeeman splitting and magnetic polaron improve and are assumed to reach saturation at high fields. All g-factor values are boosted in the presence of the external field and then fade with increasing applied fields. The electron spin-splitting energies and electron g values are ordered as Fe:CdSe > Mn:CdSe > Co:CdSe. The single-particle gaps, hole spin-splitting energies, Zeeman splitting energies and hole g values follow the order Co:CdSe > Fe:CdSe > Mn:CdSe.

Abstract This study systematically investigated the effects of defect stanene and transition metal adsorption on its geometric structure, electronic properties, and magnetism through first-principles calculations. Optimization results indicate that intrinsic stanene exhibits a typical low-curvature hexagonal honeycomb structure with a lattice constant of 4.67 Å and Sn-Sn bond length of 2.83 Å, consistent with literature findings. Following the introduction of vacancy defects, the local geometry of stanene undergoes slight distortion, with the Sn-Sn bond length increasing to 2.87 Å and the bond angle becoming 122°. However, the overall hexagonal structure and low-degree warping remain stable. Further calculations reveal that after adsorption of transition metals (such as Sc, Ti, V, Cr, Mn, etc.), spin splitting occurs near the Fermi level in the band structure of stanene, indicating that these systems possess stable magnetic ground states with local magnetic moments of 0.95 μB, 3.34 μB, and 4.73 μB, respectively. The work function calculation results reveal that the adsorption of transition metals effectively modulates the electron emission capability of stanene, with the adsorption of Mn and Co significantly enhancing surface electron emission.Charge density difference analysis indicates that metal adsorption induces redistribution of the stanene surface electronic structure, particularly exhibiting strong electron donation effects upon Mn and Co adsorption. Notably, after Cr defect adsorption, the stanene exhibits an indirect bandgap of approximately 0.042 eV, indicating a transition from metallic to semimetallic states. This provides novel insights for bandgap tuning in stanene materials. The findings offer theoretical support for potential applications of stanene in spintronics, optoelectronic devices, and quantum computing.

In this work, We present a comprehensive density functional theory based on first-principle calculation of chiral magnons in tetragonalβ-MnO2, a collinear compensated altermagnet. Our calculations confirm the thermal and dynamical stabilities of the tetragonal lattice and reveal an antiferromagnetic (AFM) ground state with momentum-dependent spin splitting, characteristic of altermagnetic behavior. Heisenberg exchange parameters derived from DFT+Wannier analysis indicate dominant nearest-neighbor AFM interactions, enabling non-degenerate magnon modes. Spin-wave magnon spectra calculated via linear spin-wave theory demonstrate clear chiral magnon behavior, manifested as nonreciprocal dispersion and chirality-dependent band splitting, arising from exchange anisotropy interactions permitted by the crystal symmetry. Furthermore, the influence of strain on magnon excitations was systematically examined, revealing that compressive strain enhances while tensile strain suppresses the spin-splitting in magnon spectra, highlighting the tunability of magnonic properties through lattice-strain engineering. Additionally, we explored the orientational spin-dependent transport features of altermagnetβ-MnO2, such as spin-dependent Seebeck coefficient as a function of chemical potential at temperature using Boltzmann transport technique. These findings highlightβ-MnO2as a promising platform for spintronic and magnonic applications, offering field-free, unidirectional spin transport and tunable chiral excitations.

ABSTRACT The Fermi surface structure in the half‐Heusler semimetallic compound LuAuSn was systematically investigated using quantum oscillation studies of high‐quality single crystals and first‐principles calculations. Clear bulk quantum oscillation signals were observed for multiple complementary physical properties, including magnetization, Hall resistance, and dynamic magnetostrictive coefficient. Quantum oscillations measured in a strong magnetic field (up to 35 T) confirmed the existence of four hole pockets and two electron pockets. Furthermore, spin splitting caused by spin–orbit coupling was discovered in the hole pockets. Our findings revealed the detailed topology of the Fermi surface in LuAuSn, which may help improve understanding of the electronic transport in this and related half‐Heusler materials.

Abstract The spin photogalvanic effect (SPGE) in Janus monolayer WSSe is systematically studied using nonequilibrium Green's function (NEGF) combined with density functional theory (DFT). Intrinsic defects such as S vacancies, Se vacancies, and Se-S swap defects introduce localized mid-gap states that modulate light absorption and carrier transitions but only marginally affect spin splitting and spin-polarized photocurrents. To enhance SPGE, substitutional doping with transition metals including Fe, Co, and Ni is explored, with Ni doping showing the most significant enhancement of spin polarization and photocurrent amplitude, particularly at high photon energies. External bias further modulates the spin current, enabling polarization reversal. These findings highlight a synergistic modulation strategy-combining intrinsic defect engineering, targeted transition metal doping, and bias control-for optimizing spin-dependent optoelectronic performance in Janus WSSe nanodevices.

A significant progress toward next-generation electronic devices that combine memory and processing functions could involve the electrical manipulation of charge carrier spin textures in semiconductors. In this context, GeTe has recently emerged as a promising ferroelectric Rashba semiconductor, exhibiting a giant spin splitting in its band structure. This remarkable property stems from the inversion symmetry breaking induced by its ferroelectric polarization. Here, we address the control of the domain structure of GeTe thin films grown on miscut silicon substrates. We show that the domain structure of the GeTe thin films is strongly influenced by the miscut direction with respect to the nominal Si(111) substrate. Considering miscut in the [1¯1¯2] direction, highly crystallized GeTe films are grown without twins, and the domain structure exhibits a reduction in domain size parallel to the step edges. In the case of [112¯] miscut direction, we evidence that thin films exhibit a predominance of twins and a complex ferroelectric structure that is affected by a large density of interfacial defects. Our results also show that the miscut direction plays a key role in the growth morphology of the GeTe thin film. All these results support the view that atomic steps on silicon substrates have a profound effect on the structure and growth morphology of GeTe thin films as well as on the domain structure via local stress relaxation mechanisms.

Topological insulators (TIs) such as Sb-doped Bi2Te3 and Bi2Se3 exhibit promising phenomena for advanced spintronics. While previous studies explored isolated doping levels; a systematic understanding of how Sb concentration influences topological behavior, Rashba-type spin splitting, and surface state formation is lacking. Here, we use density functional theory to investigate the structural, electronic, topological and transport properties of (Bi1−xSbx)2Te3 and (Bi1−xSbx)2Se3 thin films across 0 ≤ x ≤ 1. We identify pronounced Rashba spin splitting in Bi2Te3 at x = 0.5, 0.6, and 0.9 with in-plane helical spin textures. We identified the orbital origins of topological surface states and demonstrate that band inversion persists across the Sb doping range. At x = 0.2, 0.4, and 0.8, calculated surface electron mobilities are consistent with experiments and increase an order of magnitude over Sb2Te3, with minimal impact on bulk mobilities. These insights advance our understanding of TIs for spintronic and quantum device applications.

Abstract Stimulated by recent debates on the ultranodal state in FeSe, we examine the stability of Bogoliubov Fermi Surface (BFS) under Zeeman fields. As a simple model, we consider a spherical j = 3/2 model introduced by Agterberg et al. [Phys. Rev. Lett. 118 , 127001 (2017)]. By solving the BCS gap equation, we present the H − T phase diagram, showing a first-order transition in the high-field regime. Furthermore, we discuss the evolution of the BFS under Zeeman fields. Since the BFS does not necessarily consist of symmetry-protected nodes, its evolution is nontrivial; BFSs become larger in Fermi surfaces with significant spin splitting under Zeeman fields. Such BFS evolution can be observed using angle-resolved photoemission spectroscopy.