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.

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.

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.

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.

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.

Abstract The utilization of novel noncollinear antiferromagnetic materials holds great promise for the development of energy‐efficient spintronic devices. However, only a few studies have reported on the all‐electrical control of perpendicular magnetization switching using noncollinear antiferromagnets as the spin source, and the underlying mechanism behind the unconventional spin‐orbit torque (SOT) is still a topic of debate. In this work, deterministic perpendicular magnetization switching in Mn3Sn/CoTb bilayers is successfully achieved. Compared to the control samples with heavy metal as the spin source, the critical switching current density is over one order of magnitude reduced, indicating an enhanced efficiency of the out‐of‐plane charge‐to‐spin conversion in the textured Mn3Sn films. The influence of film thickness and growth temperature on the efficiency of different spin polarizations suggests potential roles of crystal quality and spin texture in spin diffusion with different spin polarization directions. These findings provide valuable insights into the crystal structure, spin‐orbit torque effects, and charge‐to‐spin conversion in Mn3Sn films, highlighting the importance of understanding interface and bulk contributions in antiferromagnetic spin transport phenomena.

We investigate magnetic field driven domain wall motion and spin-orbit torque (SOT) induced perpendicular magnetization switching of the ferrimagnetic layer in a T-type magnetic heterojunction with the structure of Pt/Co/Ta/Co81Tb19/Ta, where the bottom Co layer has in-plane magnetic anisotropy and the top Co81Tb19 layer has perpendicular magnetic anisotropy. It is found that the magnetic field driven domain wall motion and the depinning field of the Co81Tb19 layer can be effectively tuned by the thickness of the Co layer (tCo). Meanwhile, SOT-induced perpendicular magnetization switching of the Co81Tb19 layer is observed, and the critical switching current density first decreases and then increases with increasing the thickness of the Co layer. A lower critical switching current density was obtained at the optimized thickness (tCo = 1.2 nm), resulting in a 37% reduction in critical switching current density. Meanwhile, the research reveals a strong correlation between critical switching current density and magnetic anisotropy field, indicating that tuning the magnetic anisotropy is an efficient way to modulate the switching current density in a T-type magnetic structure. These results provide a new perspective on SOT manipulation and will be useful for the design of SOT-based devices.

The exchange bias effect resulting from antiferromagnetic materials plays a crucial role in spintronics devices. This effect can effectively fix the orientation of magnetization at the interface and is essential for magnetization control and switching behavior. Noncollinear antiferromagnetic materials have recently received much attention due to their novel physical properties. Here, we investigate the exchange bias effect in the noncollinear antiferromagnetic Mn3Sn/Py bilayers. It indicates the exchange bias and blocking temperature is directly related to the surface roughness and thickness of the noncollinear antiferromagnetic layer. By optimizing the thickness and deposition temperature, we achieve an exchange bias of 538Oe at 5K and a blocking temperature of 280K, which is much larger than the previous works reported for hexagonal non-antiferromagnets. Our work provides a solid foundation for understanding the exchange bias of ferromagnetic/noncollinear antiferromagnetic bilayers, and we demonstrate the potential of Mn3Sn with unique exchange bias properties, which may contribute to the future design and construction of advanced antiferromagnetic spintronic devices.

Multiferroic tunnel junctions (MFTJs) comprised of magnetic electrodes and a ferroelectric tunnel barrier have been emerging as promising candidates for nonvolatile memory applications. The recently discovered above room-temperature van der Waals (vdW) ferromagnet Fe3GaTe2 and ferroelectric α-In2Se3 provides possibilities for constructing room-temperature vdW MFTJs. In this work, by using first-principles calculations, we investigate the spin-dependent transport in vdW MFTJs with structure of Fe3GaTe2/bilayer α-In2Se3/Fe3GaTe2. We predict a giant tunneling magnetoresistance (TMR) high up to 10 000% by switching the magnetic alignments of Fe3GaTe2 and tunneling electroresistance (TER) exceeding 300% by controlling the ferroelectric configurations of bilayer α-In2Se3 in the proposed MFTJs. Furthermore, by introducing interface asymmetry and inserting monolayer of h-BN on one interface, the TMR and TER ratios of the MFTJs can be substantially enhanced. In consequence, the multi-level resistance states can be achieved by applying magnetic and electric field in asymmetric MFTJs. Our results highlight full vdW MFTJs for their potential applications in spintronic devices, particularly in the field of multilevel nonvolatile memories.

The semimetal transition metal dichalcogenides (TMD) MoTe2 have attracted extensive research interests in Spintronics. The understanding of the magnetic properties of MoTe2/Ferromagnetic (FM) heterostructures is critical to the design of novel Spintronics-based devices. However, there is lack of research on the magnetic anisotropy of the semimetal TMD/FM. Here, we demonstrate the in-plane crystalline orientation-related magnetic properties of MoTe2/Co to clarify the relationship between the crystalline orientation and the magnetic anisotropy. We carried out the studies of crystalline orientation-related magnetic anisotropy in 1T-MoTe2/Co heterostructures from both experiments and first-principles calculations. Our results show that for Co with different thicknesses, the easy axis of Co film is along the b-axis of MoTe2 with uniaxial magnetic anisotropy. It is also consistent with the results of our theoretical results. When Co film thickness increases, the magnetocrystalline anisotropy (MCA) oscillates around a constant value with a lower MCA along the out-of-plane direction. Meanwhile, the demagnetization energy which increases linearly as a function of Co thickness, which would make the easy axis in-plane. Our work may give a fundamental inspiration for Spintronics based devices with semi-metallic TMDs/ferromagnetic materials. (C) 2021 Published by Elsevier B.V.

Lithium phosphorus sulfuric oxide nitride (LiPSON) prepared by radio frequency sputtering is investigated as a transparent solid lithium‐ion conductor for use in all‐solid‐state electrochromic (EC) devices. The LiPSON layers are characterized by X‐ray photoelectron spectroscopy (XPS) and their electrical characteristics are studied by temperature‐dependent impedance spectroscopy. Half‐cells of LiPSON deposited on tungsten oxide (WOx) in contact with 1 m LiClO4 in propylene carbonate are studied by electrochemical impedance spectroscopy (EIS) and spectroelectrochemical measurements by cyclic voltammetry and chronoamperometry. A significant influence of LiPSON deposition conditions on the EC characteristics of WOx is observed in the achievable transparency change, as well as the color impression in the bleached and colored state. Formation of a solid−electrolyte interface (SEI) is indicated that leads to poor EC performance with long switching times of 20−60 min. Appropriate deposition conditions for LiPSON are established that maintain a good EC activity of WOx. An all‐solid‐state EC device is assembled of WOx/LiPSON with vanadium titanium oxide as counter electrode and aluminum‐doped zinc oxide as back contact. Temperature‐dependent EIS and spectroelectrochemical measurements show that in such an all‐solid‐state stack, the detrimental contact resistance could be avoided and switching times of less than 60 s are achieved.

Spin-dependent transport in full van der Waals (vdW) giant magnetoresistance (GMR) junctions with the structure of Fe3GeTe2/XTe2/Fe3GeTe2 (X = Pt, Pd) is investigated by using first-principles calculations. The ballistic conductance, magnetoresistance (MR), and resistance-area product (RA) are calculated in a current-perpendicular-to-plane (CPP) geometry. A giant magnetoresistance of around 2000% and RA less than 0.3 Omega mu m(2) are found in the proposed vdW CPP GMR. In addition, the spin-orbit-coupling effect on transport and anisotropy magnetoresistance (AMR) are also investigated. The calculated AMR is found to be around 20% in the Fe3GeTe2/trilayer PdTe2/Fe3GeTe2 CPP GMR. Both GMR and AMR in the proposed vdW CPP GMR mainly originate from the bulk electronic structure properties of Fe3GeTe2. This work demonstrates a vdW CPP GMR with superior advantages, including perpendicular magnetic anisotropy, large GMR, low RA, and sizable AMR, which may stimulate future experimental explorations and should be appealing for its application in spintronic devices, including magnetic sensors and memory.

Fe undergoes a corrosion process under aerobic conditions. Oxidized forms of Fe lose malleability, durability, and other critical physical properties. For spintronic applications, alloy forms or capping layers are used to modulate the properties of Fe. Observing the Fe(111) spin structure is critical for practical applications. We suggest a method of coating Fe to retain its original magnetic properties. Thanks to monolayer graphene (MLG) growth, the properties of the Fe spin structure do not change, even under ambient conditions. Through angle-resolved photoemission spectroscopy (ARPES) and low-energy electron diffraction (LEED) measurements, we also found that interfacial band structures are modulated due to the presence of MLG.

Multiferroic tunnel junctions (MFTJs) have aroused significant interest due to their functional properties useful for nonvolatile memory devices. So far, however, all of the existing MFTJs have been based on perovskite-oxide heterostructures limited by a relatively high resistance-area (RA) product unfavorable for practical applications. Here, using first-principles calculations, we explore spin-dependent transport properties of van der Waals (vdW) MFTJs which consist of two-dimensional (2D) ferromagnetic FenGeTe2 (n = 3, 4, 5) electrodes and 2D ferroelectric In2Se3 barrier layers. We demonstrate that such FemGeTe2/In2Se3/FenGeTe2 (m, n = 3, 4, 5; m ≠ n) MFTJs exhibit multiple nonvolatile resistance states associated with different polarization orientation of the ferroelectric In2Se3 layer and magnetization alignment of the two ferromagnetic FenGeTe2 layers. We find a remarkably low RA product (less than 1 Ω·μm2) which makes the proposed vdW MFTJs superior to the conventional MFTJs in terms of their promise for nonvolatile memory applications.

The efficient electrical control of the magnetic states of antiferromagnets is one of the main focus in antiferromagnetic spintronics. In this work, the voltage-controlled magnetic anisotropy (VCMA) effect in two representative antiferromagnets L1(0)-type MnPt and MnPd thin films has been investigated by employing first-principles calculations. Our results indicate that both of the MnPt and MnPd films show in-plane magnetic anisotropy and the magnetic easy axis points either along [1 0 0] or [1 1 0] direction depending on the film thickness. The applied electric field in the range of -0.3 V/angstrom and + 0.3 V/angstrom (vacuum as dielectric) leads to the change of magnetocrystalline anisotropy of both films at the order of tens of mu J/m(2). Especially, for MnPt film with thickness of two unit cells on Pt(0 0 1), it shows that the moderate electric field is able to switch the in-plane magnetic easy axis between [1 0 0] and [1 1 0] directions. For MnPd thin films, the VCMA effect shows generally linear dependence on the electric field and the VCMA coefficients are estimated in the range of 2.7 to 22.6 fJ/V/m. Our calculation results may stimulate future investigations on the VCMA effect of metallic antiferromagnetic films and pave the possible applications in memory device.

The development of ultralow power and high density nonvolatile magnetic random access memory stimulates the search for promising materials in magnetic tunnel junction with large voltage-controlled magnetic anisotropy (VCMA) efficiency. In this work, we investigate the 4dand 5dtransition metal interlayer effect on perpendicular magnetic anisotropy (PMA) and VCMA at Fe/MgO interface by using first-principles calculations. Large PMA more than 11 mJ m(-2)is found at Fe/MgO interface with Pt insertion layer and the mechanism for PMA is clarified based on the second order perturbation theory. Furthermore, we find that the magnitude and the sign of VCMA efficiency are varied by introducing different insertions at Fe/MgO interface. The Re and Os interlayers lead to a sizable increase in both of the PMA and the VCMA coefficient. Our findings may further emphasize the essential importance of the interface structure on PMA and VCMA and may offer new material platforms for low-power consumption spintronic devices.

The level of short circuit current in power system is increasing rapidly, and flux-coupling superconducting fault current limiter based on paralleled superconducting windings can effectively limit short-circuit current by the increased impedance after decoupling of the windings. The superconducting winding with high coupling factor is the core component of this SFCL, and the voltage distribution of windings may be uneven depending on the winding type and operating condition. This could affect the quenching of superconducting windings, and even endanger the insulation. In this paper, the voltage distribution of pancake-winding and layer-winding is theoretically analyzed, then simulations considering different operating conditions were carried out, and two prototypes were processed and the experiment results are in accordance with simulation to some degree.

Superconducting magnetic energy storage (SMES) is composed of three main components, which are superconducting magnet, power conditioning system (PCS), and system controller to fulfil the task of power exchange between the power system and SMES. In addition to the basic design of single component, the interaction between different components of SMES should be considered during the design process. Firstly, the dynamic power compensation has effect on the losses of SMES magnet, which should be considered in the magnet design. Secondly, the dynamic response characteristic of PCS influences the power response capability of SMES. Thirdly, the high frequency pulse width modulation (PWM) pulse voltage generated by the PCS and applied directly to the SMES magnet could induce insulation issues of the magnet, which is the key factor of ensuring the security of the magnet. Considering the mutual effect of SMES components comprehensively, an integrated design method for SMES system is proposed in this paper. To evaluate the effectiveness of the proposed integrated design method, a 3.8 MJ/1.2 MW SMES system applied in a micro grid is designed comprehensively.

Fault current limiter (FCL) is commonly applied as a current-limiting device to improve the stability of the power system. A flux-coupling type superconducting FCL (FC-SFCL) which mainly consists of a current-limiting unit has been developed. Because of its low steady-state impedance and larger current-limiting impedance at pre-and post-fault, it is regarded as a possible way to restrict fault currents. In this paper, ac loss performances of three structures with different winding methods under three operations were discussed. Then an experimental platform for a small-scale prototype was set up, and several relevant experiments were implemented to test current reduction capacity and loss levels. In theory, the resistive loss obtained by integrating the instantaneous power corresponds to the ac losses of the current-limiting unit. It provides a feasible way to measure ac losses of a magnet, but it needs further verification.

High-voltage DC arrester is one of the key equipment for overvoltage protection of ultra-high voltage DC (UHVDC) transmission system. This device plays a decisive role in the insulation level of the whole process. The current distribution between resistance pieces of multi-column parallel arresters is non-uniform, which affects the overall energy absorption capacity of arresters. First, a real failure case of ±500 kV Xiluodu-Nuozhadu HVDC project is introduced. Then, the analysis of the specific failure case is proposed. Finally, a corresponding model is built on PSCAD/EMTDC to study the current distribution characteristics.