The pursuit of beyond-Moore information technologies has stimulated the exploration of novel information carriers, such as electron spin, orbital, and magnon, beyond electron charge. Efficient interconversion among these degrees of freedom and precise control over the information states are crucial for advancing nanoelectronic devices. However, a direct coupling between orbital angular momentum (L) and magnons (M) has remained elusive, and magnetization switching through orbital-to-magnon (L-M) conversion has not yet been achieved. Here, we report the experimental demonstration of L-M conversion in an orbital metal/antiferromagnetic insulator bilayer at room temperature, with an efficiency over an order of magnitude higher than that in traditional orbital systems lacking the L-M process. Consequently, we achieved efficient room-temperature perpendicular magnetization switching in a CoFeB ferromagnetic layer mediated by this new mechanism. Our findings establish a direct link between orbitronics and magnonics, providing a new platform for the development of advanced nano-devices based on orbital-driven magnonic phenomena.

Noncollinear antiferromagnets show great potential for next-generation spintronic devices due to their unique spin textures and ultrafast dynamics, with Kagome-lattice Mn3Sn a key spin-orbit torque (SOT) candidate enabled by room-temperature unconventional spin polarization. However, the impact of crystal orientation on its SOT efficiency remains unaddressed. Herein, we combine experiments and first-principles calculations to investigate Kagome-facet-dependent unconventional out-of-plane SOT in Mn3Sn, confirming z-direction polarized spin current and unconventional spin polarization in the material. Strikingly, (112̅0)-oriented Mn3Sn films exhibit 13-fold higher unconventional SOT efficiency ξz associated with z-direction spin polarization than (0002)-oriented counterparts, a behavior governed by Kagome lattice symmetry and facet-dependent spin transport. First-principles calculations further verify the Kagome plane's critical role in enhancing anisotropic spin textures and transport properties. This crystal-facet engineering strategy resolves the longstanding ambiguity in SOT anisotropy of noncollinear antiferromagnets and establishes Mn3Sn as a versatile platform for energy-efficient antiferromagnetic spintronic devices.

Magnetic skyrmions are localized magnetic structures that retain their shape and stability over time, thanks to their topological nature. Recent theoretical and experimental progress has laid the groundwork for understanding magnetic skyrmions characterized by negligible net magnetization and ultrafast dynamics. Notably, skyrmions emerging in materials with altermagnetism, a novel magnetic phase featuring lifted Kramers degeneracy-have remained unreported until now. In this study, we demonstrate that BiFeO3, a multiferroic renowned for its strong coupling between ferroelectricity and magnetism, can transit from a spin cycloid to a Neel-type skyrmion under antidamping spin-orbit torque at room temperature. Strikingly, the altermagnetic spin splitting within BiFeO3 skyrmion can be reversed through the application of an electric field, revealed via the Circular photogalvanic effect. This quasiparticle, which possesses a neutral topological charge, holds substantial promise for diverse applications-most notably, enabling the development of unconventional computing systems with low power consumption and magnetoelectric controllability.

Specific power generation capacity ΓP is a critical performance metric for micro-thermoelectric generators (μ-TEGs), yet the best reported values are constrained to a few hundred µW cm-2 K-2. Here, we report a giant ΓP of ∼5000 µW cm-2 K-2 in μ-TEGs based on the anomalous Nernst effect (ANE) in medium-entropy (FeCoNi)100- xPtx films. Leveraging the high-entropy cocktail strategy, we have simultaneously achieved a large anomalous Nernst thermopower Sxy (>1.4 µV K-1) and low resistivity ρxx (<85 µΩ cm), and suppressed the classical and quantum size effects on both Sxy and ρxx at the optimal composition of x ≈ 50 and film thickness of a few nanometers, enabling the record-high ΓP. The underlying mechanism arises from cocktail-driven modulation of energy-band smearing, density of states, and Berry curvature at the Fermi surface, resulting in an ultrashort carrier mean-free-path of ∼3 nm, an ultrahigh carrier density of ∼1023 cm-3, and a large anomalous Nernst conductivity above 1.7 A m-1 K-1. This claim is further supported by first-principles calculations, which collectively highlight the experimental and theoretical potential of utilizing such materials for high-performance μ-TEG applications.

Magnetic materials support both time-reversal-even (T-even) and time-reversal-odd (T-odd) spin Hall currents, yet their underlying microscopic origins remain elusive. Here, we elucidate the spin Hall effect (SHE) in collinear ferromagnets by treating spin-orbit coupling (SOC) as a perturbation that breaks spin-group symmetry, thereby revealing how magnetic order activates distinct spin Hall response. To first order in SOC, we identify two dominant T-even SHE mechanisms: a magnetization-independent conventional contribution and a magnetization-dependent channel associated with anomalous Hall charge transport. At the same order, the leading T-odd magnetic spin Hall effect (MSHE) originates from the exchange interaction between the conventional spin current and the local magnetization. At second order in SOC, we further uncover a distinct T-odd planar spin Hall mechanism. Our spin-symmetry analysis is corroborated by first-principles calculations, which reveal a pronounced anisotropic magnetic spin Hall effect whose magnitude can be comparable to the T-even spin Hall conductivity (SHC) when the magnetic moment is tilted away from the principal crystallographic axes. These findings clarify the microscopic origins of the SHC in collinear ferromagnets and pave the way for ferromagnet-based spin current sources with versatile properties in spintronic applications.

Conventional spin and charge Nernst effects emerge from the spin-orbit coupling mechanism. Here we present a theoretical and computational investigation of Nernst responses in anisotropic ferromagnets, systematically analyzing contributions originating from both electrons and magnons. Through symmetry analysis, we identify giant intrinsic Nernst conductivities in MnAl(101) that persist at room temperature. Remarkably, the calculated spin and charge Nernst conductivities at 300 K reach values of 6.7h/2e A(mK)-1 and 33.7 A(mK)-1, respectively, which even exceed the spin-orbit coupling driven mechanism. Our findings establish low-Z transition metal alloys as a promising materials platform for spin-caloritronic applications, while providing fundamental insights into the interplay between crystalline symmetry and transverse thermoelectric spin transport.

Current-induced spin-orbit torques (SOTs) provide a crucial mechanism for the electrical control of antiferromagnetic order. However, SOTs in antiferromagnets (AFMs) and the resulting spin dynamics remain largely unexplored. Here we present a complete classifications of SOTs in bulk collinear AFMs based on magnetic point group symmetry. Depending on the symmetry operations that connect the two antiparallel spin sublattices, the SOTs are categorized into six distinct types. We focus on three representative AFMs in which the spin sublattices are linked by fractional translation, spatial inversion, or neither of these symmetries, respectively. Using first-principles calculations within Kubo linear response theory, we compute the SOTs on each sublattices, and simulate the N & eacute;el vector dynamics via the Landau-Lifshitz-Gilbert equation. In the prototypical PT-symmetric AFM and the inversion symmetry breaking altermagnet, our simulations reveal that deterministic N & eacute;el vector switching can be driven entirely by field-like torques. Moreover, all-electrical writing of a single domain state with preset N & eacute;el vector direction, as well as 180 degrees deterministic switching is attainable. This work sheds light on current-controlled antiferromagnetic orders in collinear AFMs. In particular, for the inversion symmetry breaking altermagnet, the demonstrated electrical writing and reading of the N & eacute;el vector hold promise for antiferromagnetic memory applications.

Current-induced spin-orbit torques (SOTs) are central to the electrical manipulation of magnetic order in spintronic devices. In transition-metal/collinear ferromagnet bilayers, field-like and damping-like torques have been described only phenomenologically via the spin or orbital Hall effect, lacking a rigorous symmetry-based foundation. The precise role of spin-orbit coupling (SOC) in both the Edelstein effect and SOTs has remained unresolved. Here we develop a spin-group symmetry theory for the Edelstein effect and SOTs in collinear ferromagnets, treating SOC as a symmetry-breaking perturbation. For 4mm (C4v) point group symmetry, we derive the full forms of field-like and damping-like torques, which arise predominantly from first- and second-order SOC. We further show that SOTs in both orbital-Hall-dominated Ti/Ni and spin-Hall-dominated Pt/CoFe bilayers originate at first-order SOC. Taking the 3m (C3v) torque as a paradigmatic example, we elucidate the role of second- and higher-order SOC torques in field-free switching of perpendicular magnetic anisotropy. Remarkably, in PtMnSb, we demonstrate that SOTs under certain point group symmetries deviate from the conventional form: zeroth- and first-order SOC contributions vanish identically, with the leading SOT emerging at second order. All symmetry-based predictions from spin-group theory are in excellent quantitative agreement with first-principles calculations. Our work establishes a unified symmetry framework for the microscopic understanding of the Edelstein effect and current-induced spin torques in ferromagnetic systems.

It is established that the polarity of a time-reversal-odd (𝒯-odd) physical quantity can be reversed under the 𝒯 operation. Here, we use the spin-group analysis to directly demonstrate that the 𝒯-odd magnetic spin Hall effect in ferroelectric altermagnets can be switchable by electric fields beyond the 𝒯 operation. This arises from the ferroelectric switching of the nonrelativistic spin splitting, which swaps the roles of spin up and down channels in the reciprocal space. As a result, the 𝒯-odd spin conductivity that are proportional to the spin-polarized conductivity difference reverses its polarity upon polarization switching. We identify spin-group operations to switch both the polarization and the magnetic spin Hall effect simultaneously for non-centrosymmetric spin point groups. Then, we exemplify those phenomena in the ferroelectric altermagnet VOI_2 monolayer based on density functional theory calculations and an effective Hamiltonian analysis. Our findings not only provide novel strategies to switch the magnetic spin Hall effect using the dissipation-free electric field but also open a promising avenue for electrically programmable spintronic devices.

The emergence of altermagnets has driven groundbreaking advances in spintronics. Notably, d-wave altermagnets support non-relativistic spin transport, efficient charge-to-spin conversion, and T-odd spin currents. In addition, their integration as electrodes in antiferromagnetic tunnel junctions (AFMTJs) enables a tunneling magnetoresistance (TMR) effect, allowing electrical detection of N & eacute;el vectors for next-generation memory devices. In this work, we investigate the non-relativistic spin transport properties of the quasi-two-dimensional (quasi-2D) d-wave altermagnet KV2Se2O and the TMR effect in KV2Se2O -based AFMTJs via first-principles calculations. Our results reveal that KV2Se2O exhibits both non-relativistic longitudinal spin polarization and a spin Hall angle exceeding 60% at room temperature, while KV2Se2O -based AFMTJs achieve a giant TMR ratio of 8.20 & times; 10(13)%, which remains robust against Fermi-level shifts. These findings highlight the anisotropic spin polarization inherent to d-wave staggered magnetism and underscore the critical role of Fermi surface topology in enhancing T-odd spin transport and the TMR effect in AFMTJs.

Two-dimensional (2D) reticular framework films featuring highly accessible surface areas, tunable active sites, and well-defined channels are promising candidates for flexible in-plane micro-supercapacitor (MSC) electrodes. However, the interlayer Van der Waals forces in 2D heterojunctions can limit mass/charge transport. Herein, we design a non-Van der Waals force bonded heterojunction of covalent organic frameworks (COFs) and metal–organic frameworks (MOFs) linked by metal-ion coordination. A COF@MOF monolithic nanofilm is constructed by growing MOF (M3(HHTP)2) in situ on the COF (COFTD) surface, using nickel (Ni) as the optimal metal to connect the two layers and form a sandwich electrode. We further explore various transition metals in M3(HHTP)2, from manganese (Mn) to zinc (Zn), to adjust the electronic structure and charge redistribution. The optimal MSC-Ni-COFTD@Co3(HHTP)2 device exhibits an impressive specific capacitance (1645.3 ​F ​cm−3 at 10 ​mV ​s−1), a high energy density (146.3 ​mWh cm−3), as well as superior cycling and bending stability. This work offers an innovative perspective on overcoming the mass transfer and electron migration limitations of 2D reticular frameworks for miniaturization and wearable energy storage electronics.

Ferromagnetic metals, with the potential to generate spin current with unconventional spin polarization via the spin Hall effect, offer promising opportunities for field-free switching of perpendicular magnetization and for spin–orbit torque devices. In this study, we investigate two distinct spin Hall mechanisms in 3d ferromagnetic metals including spin–orbit coupling driven spin Hall effect in Fe, Co, Ni, and their alloys, and non-relativistic spin Hall effect arising from anisotropic spin-polarized transport by taking L10-MnAl as an example. By employing first-principles calculations, we examine the temperature and alloy composition dependence of spin Hall conductivity in Fe, Co, Ni, and their alloys. Our results reveal that the spin Hall conductivities with out-of-plane spin polarization in 3d ferromagnetic metals are on the order of 1000 ℏ/2e(Ω cm)−1 at 300 K, but with a relatively low spin Hall angles around 0.01–0.02 due to the large longitudinal conductivity. For L10-MnAl(101), the non-relativistic spin Hall conductivity can reach up to 10 000 ℏ/2e(Ω cm)−1, with a giant spin Hall angle around 0.25 at room temperature. By analyzing the magnetization switching process, we demonstrate deterministic switching of perpendicular magnetization without an external magnetic field by using 3d ferromagnetic metals as spin current sources. Our work may provide an unambiguous understanding of the spin Hall effect in ferromagnetic metals and pave the way for their potential applications in related spintronic devices.

Spin-splitting antiferromagnets with spin-polarized band structures in momentum space have garnered intensive research attention due to their zero net magnetic moments, ultrafast spin dynamics as conventional antiferromagnets, and spin-polarized transport properties akin to ferromagnets, making them promising candidates for antiferromagnetic spintronics. However, unlike spin-torque switching of ferromagnets by electric current, efficient electric control of spin-splitting antiferromagnetic order remains challenging. In this work, we identify prototypes of multiferroic spin-splitting antiferromagnets, including BiFeO3, Fe2Mo3O8, and compensated ferrimagnet GaFeO3 with ferroelectric polarization as well as spin-polarized electronic structures. We establish design principles for the spin-splitting multiferroic antiferromagnets and compensated ferrimagnet, elucidating the band symmetry features in the Brillouin zone. We demonstrate that the spin polarization in spin-splitting magnets, despite zero net magnetic moment, can be switched by ferroelectric polarization, providing an efficient means of controlling the antiferromagnetic order. Our work may inspire future development of novel multiferroic functional magnets with zero magnetic moments and pave the way for their applications in magnetoelectric spintronic devices.

A vital goal in spintronics is the efficient electrical generation of spin currents, a pursuit that has recently focused on using antiferromagnets (AFMs) as spin current sources. It has been demonstrated that antiferromagnets with broken PT symmetry (parity + time reversal) can efficiently generate longitudinal and transverse spin currents. At the same time, it has been generally thought that antiferromagnets with PT symmetry (PT-AFMs) forbid the longitudinal spin polarization due to their spin-degenerate band structure. Here, in contrast to this common expectation, we show, using theoretical analysis based on magnetic point group symmetry, that most PT-AFMs can generate longitudinal spin currents due to spin-orbit coupling. Using density-functional theory, we calculate the longitudinal spin conductivity of representative PT-AFMs, L10-MnPt and Mn2Au, and show that its magnitude is comparable to that of their PT-broken counterparts. Our symmetry-enabled classification of antiferromagnets and theoretical results for the longitudinal spin conductivity in representative PT-AFMs expands our understanding of spin transport and shows the possibility of robust spin-current generation in a broad range of spin-degenerate antiferromagnets.

Current-induced spin torque is essential and crucial in spintronics. In this work, we systematically investigate the spin torque in transition metal (TM)/ferromagnet (FM) bilayers by using first-principles calculations and taking into account the phonon scattering at room temperature. To examine the spin and orbital Hall contributions, the studied transition metals include 5d heavy metals Pt, W, Au, and Ta as well as 3d light metals Ti, V, Cr, Cu, etc. We found that in TM/CoFe bilayers with typical 3d and 5d transition metals, the spin torque on CoFe mainly originates from the spin Hall mechanism, with the magnitude and sign of the damping-like torque efficiency consistent with those of the spin Hall conductivity (SHC). In TM/Ni bilayers, the spin torque is contributed by three mechanisms, including the spin and orbital Hall effect in the TM, as well as self-torque in Ni. For TM/Ni bilayers, when SHCs are large in TMs, for instance in W and Pt, the spin torques are mainly contributed by the spin Hall effect rather than the orbital Hall effect due to the partial cancellation of orbital and self-torque. For other cases, including Ti/Ni, V/Ni, and Ta/Ni, the orbital Hall torques also compete with either self-torque in Ni or the spin Hall effect in the TMs, which leads to the resultant spin torque efficiency not being pronounced. Our work reveals the less efficient contribution of the orbital Hall effect than the spin Hall effect on the spin torque in TM/FM bilayers.

Noncollinear antiferromagnets have emerged as promising platforms for next-generation spintronic devices due to their unique spin textures and unconventional spin-polarized currents. However, the limited understanding of factors governing the out-of-plane spin polarization efficiency (4z) in materials such as Mn3Sn hinders their practical application. Here, we demonstrate a strain-engineering strategy to significantly enhance 4zby tailoring the lattice constant c of Mn3Sn thin films. Through controlled annealing processes, we induce tunable crystalline strain in Mn3Sn and systematically investigate its impact on spin-to-charge conversion via angle-resolved spin-torque ferromagnetic resonance measurements. Remarkably, the unconventional dampinglike torque efficiency increases by over an order of magnitude when the lattice constant c approaches its equilibrium value, attributed to strain-modulated chiral spin configurations. First-principles calculations corroborate the critical role of lattice strain in amplifying anisotropic spin textures and spin-orbit coupling. This work not only elucidates the structural origin of spin polarization anisotropy in noncollinear antiferromagnets but also establishes a scalable route for designing high-efficiency spin sources compatible with semiconductor integration. The findings advance the development of low-power, all-electric spintronic devices based on strain-engineered antiferromagnetic heterostructures.

Altermagnets,a class of unconventional antiferromagnets with non-relativistic spin-splitting,offer promising potential for antiferromagnetic spintronic devices.While many altermagnets are limited by either low magnetic transition temperatures or weak spin splitting,the recently discovered metal CrSb,with high Néel temperature(TN=710 K)and significant spin-splitting due to its unique spin space group,provides a robust platform for remarkable tunneling magnetoresistance(TMR)in collinear all-antiferromagnetic tunnel junctions(AATJs).This study systematically investigates the spin-polarized Fermi surface of CrSb and spin-dependent electron transport in CrSb-based AATJs.The CrSb/β-InSe/CrSb junction with a three-monolayer InSe barrier exhibits a TMR ratio of approximately 290％,with energy-dependent analysis revealing TMR ratios that may exceed 850％when considering the shift of the Fermi energy.We also demonstrate the angle-dependent TMR of CrSb-based AATJs by adjusting Néel vector orientations.Our findings might provide strong theoretical support for CrSb as a versatile building block for all-antiferromagnetic memory devices.

Altermagnets,a new type of collinear antiferromagnet,exhibiting non-degenerate electron and magnon dis-persion in momentum space have attracted intensive research attention.We theoretically analyze the origin and feature of chiral magnon splitting in representative altermagnets including tetragonal RuO2,hexagonal MnTe,and orthorhombic LaMnO3.The magnon spin transport properties including spin Seebeck and spin Nernst co-efficients have been investigated.Through these materials,we demonstrate the difference of chiral splitting in d-wave and g-wave antiferromagnet on magnon transport.RuO2 with planar magnon splitting exhibits significant magnon spin Nernst and magnon spin Seebeck anisotropy in(110)and(001)planes,whereas MnTe,due to its bulk-like magnon splitting,is incapable of producing magnon spin Nernst effect.Our work may provide in-depth understanding on the mechanisms of nonrelativistic magnon splitting and thermal spin transport in altermagnets.

The development of next‐generation spin nanomemory systems faces the challenge of achieving nonvolatile electrical control of magnetic states in magnetic tunnel junctions. Here, a strategy is proposed using trilayer van der Waals heterostructures combining an A‐type antiferromagnetic YBr 2 bilayer and a ferroelectric Al 2 Se 3 monolayer. Nonvolatile modulation of the ferroelectric polarization direction of Al 2 Se 3 can flip the interlayer magnetic coupling of YBr 2 between ferromagnetic and antiferromagnetic states. The interlayer magnetic phase transition is caused by the band structure shift and interfacial charge transfer induced by the polarization field. The TiTe 2 /2L‐YBr 2 /Al 2 Se 3 /TiTe 2 multiferroic devices achieve a fully electrically controlled tunneling magnetoresistance with a ratio of up to 11550% and an exceptionally low resistance‐area product of 0.28 Ω µm 2 by establishing a good P‐type Ohmic contact between the TiTe 2 electrode and the central heterojunction. There is also a perfect spin filtering effect. This work provides new perspectives for the development of low‐power, fast‐response, nonvolatile and fully electrically controlled spintronic memory devices.

Zigzag graphene nanoribbons (ZGNRs) with two antiferromagnetic coupled edges possess PT (combined spatial inversion and time reversal) symmetry and spin double degenerate electronic structures. By breaking PT symmetry via the structure design, we are able to generate spatial spin density in twisted bilayer ZGNRs (TBZGNRs) with different stacking configurations and twisted angles, forming a class of quasi-one dimensional carbon nanoribbon antiferromagnets. We investigate the spin transport in TBZGNRs by employing the non-equilibrium Green's functions method and reveal that the electric current is nonreciprocal and spin-polarized in non-PT symmetric TBZGNRs. Moreover, in PT symmetric TBZGNRs, the spin degenerate can be lifted by applying bias voltage. It shows unique nonreciprocal spin transport with opposite spin-polarization under positive and negative bias voltages. Our results indicate that TBZGNRs should be useful carbon-based materials exhibiting antiferromagnetic order and spin-polarized transport. Thus, this work provides a strategy to achieve spin transport in graphene nanoribbons and carbon-based spintronics via the structural design.