van der Waals (vdW) heterojunctions formed between GaN and transition metal dichalcogenides (TMDs) hold promise for application in broadband photodetection. Here, we investigate the electronic structure of GaN/WSe2 heterojunctions. Ga-terminated GaN surfaces exhibit strong covalent interactions with WSe2, and the interfacial charge significantly perturbs the heterojunction band structure, thereby preventing effective modulation of the band alignment via GaN conductivity. In contrast, passivated GaN surfaces (pseudo-hydrogen) form robust vdW heterojunctions with WSe2, and their band alignment can be tuned from type-II to type-I through controlled GaN doping. This is consistent with the results we previously tested in our experiments. Our calculations provide good design guidance for van der Waals heterojunctions between GaN and 2D materials.

Soft magnetic materials (SMMs) play a critical role in high-frequency energy conversion technologies for power electronics and renewable energy applications. However, with the rapid adoption of third-generation widebandgap semiconductors, there is an urgent demand for advanced SMMs in the MHz-range switching power supply applications that exhibit ultra-low losses, high saturation magnetization, and thermal stability. Here, we reported excellent soft magnetic properties of 800 nm-thick epitaxial Th2Ni17-type Gd2Co17 alloys films with an intrinsic easy-plane hexagonal magnetocrystalline anisotropy, featuring a coercivity (Hc) below 1273 A/m, a room-temperature saturation magnetization (Ms) exceeding 8.5 x 105 A/m, and a Curie temperature (Tc) reaching 1041 K. It's found that the hexagonal magnetocrystalline anisotropy is modulated by inevitable uniaxial strain anisotropy during grow progress, which gives rise to a real and imaginary parts of permeability of 72 and 0.2 at 400 MHz, a magnetic loss tangent (tan delta mu) of 0.002 at 400 MHz, a natural resonance frequency (fr) of 1.1 GHz, and a Snoek's product (SP) of 90 GHz. Furthermore, doping with 2 % Fe, while preserving the original crystal structure of Gd2Co17, significantly enhances the high-frequency soft magnetic performance. The (Gd2Co17)0.98Fe0.02 films hold promising soft magnetic properties, with a real and imaginary parts of permeability of 141 and 0.4 at 400 MHz, a tan delta mu of 0.002 at 400 MHz, and an elevatedfr of 1.5 GHz, and a superior SP of 255 GHz with higher Ms above 1.1 x 106 A/m and low Hcbelow 1591 A/m. Our work reveals the broad application prospects of rare-earth transition-metal alloys with planar anisotropy in the MHz-range applications.

Surface acoustic waves (SAWs) have emerged as an efficient approach for the acoustic manipulation of magnetization and the generation of spin currents, attracting significant attention in spintronics. In this work, we systematically investigate the magnetotransport properties of a lithium niobate/nickel (LiNbO3/Ni) device under nonresonant SAW excitation using time-resolved electrical measurements. The time-resolved SAW-induced voltage is measured as a function of delay time, external magnetic field magnitude, and magnetic field orientation. The SAW-induced voltage exhibits pronounced magnetization-dependent modulation, characterized by a double-valley structure with two valleys appearing near zero magnetic field and the magnetization switching field during magnetic field sweeps and a fourfold angular dependence. These features differ markedly from the single switching-related feature and twofold angular dependence expected for the conventional anisotropic magnetoresistance effect (AMR). We attribute the SAW-induced response to dynamic strain-mediated magnetoelastic coupling, which modulates the magnetization configuration and spin-dependent scattering in the Ni film. Our results demonstrate a feasible route for using SAWs to probe and control strain-mediated spin-lattice interactions in magnetic thin-film devices.

Magnetic interactions have long served as the most robust and widely used approach for realizing nonreciprocity, with an externally applied magnetic field breaking time-reversal symmetry (TRS) and chiral photon-magnon interactions introducing spatial asymmetry. In this work, we investigate the chirality mechanisms essential for magnetic nonreciprocity from a unified experimental and theoretical perspective. We begin by examining conventional chiral interactions that generate chiral electromagnetic fields through specially designed structures, and then place particular emphasis on synthetic chirality enabled by nontrivial phase accumulation in traveling-wave-mediated coupling systems. We establish a microscopic theoretical framework that maps field polarization onto the phase of a complex coupling strength and validate it with systematic experiments, thereby providing a consistent formalism that describes both conventional and synthetic chirality. Notably, we highlight the symmetry properties and the unique features of synthetic chirality that distinguish it from conventional nonreciprocal mechanisms.

The linewidth of ferromagnetic resonance (FMR) in ferrites reflects the damping factor and energy loss, and is a primary focus in magnetism and spintronics. However, the mechanism of broadening FMR spectrum in bulk ferrite is still elusive. Here, we investigate the FMR of MgAl0.5Fe1.5O4 polycrystalline bulk and single-crystal thin film, and find that the linewidth increases by one order of magnitude when MgAl0.5Fe1.5O4 transitions from single-crystal thin film to polycrystalline bulk. The breadth of linewidth in bulk material results from inhomogeneity of resonance fields, which originates from the random grain orientation distribution and inter-grain variations. These results demonstrate that the broadened FMR spectrum of polycrystalline ferrite bulk can be regarded as a superposition of narrow FMR spectra of single-crystal grains, offering a unified explanation for anomalous linewidth broadening and asymmetric FMR spectra observed in low-damping polycrystalline ferrites. Our work provides an accurate understanding of FMR linewidth in polycrystalline ferrites.

Understanding the interconversion between charge current and spin current in antiferromagnetic materials is crucial for advancing antiferromagnetic spintronic devices. In this work, we utilize the second harmonic technique and the spin Hall magnetoresistance method to investigate the spin current generation in Mn3Ir/Co bilayers. The angular dependence of the second harmonic Hall voltage shows that only a y-polarized spin current is generated, which exerts spin-orbit torques on Co magnetic moments. Contrary to the positive spin Hall magnetoresistance induced by y-polarized spin current, we observe the anomalous negative spin Hall magnetoresistance in Mn3Ir/Co bilayers. By further investigating the Mn3Ir thickness dependence of the negative spin Hall magnetoresistance and spin-orbit torque, we demonstrate that the negative spin Hall magnetoresistance originates from the interconversion between charge current and spin current driven by interfacial spin-orbit coupling. Our findings provide compelling evidence for interfacial spin-orbit coupling conversion at the antiferromagnetic/ferromagnetic bilayer interface. This indicates that the interface engineering is essential for optimizing noncollinear antiferromagnetic spintronic devices.

Electron quantum transport in disordered systems has attracted great interest because of its fundamental importance in condensed matter physics. Although the incipient Anderson localization related to electron-phonon scattering or electron-electron interactions has been reported in several nonmagnets and ferromagnets, it has not been reported in antiferromagnets so far, and the role of electron-magnon scattering remains elusive. In this work, we report the observation of incipient Anderson localization and dimensional crossover in antiferromagnetic gamma-FeMn films. Temperature (T)-dependent conductivity (sigma) exhibits an additional linear-T contribution below 30 K, attributed to the two-dimensional (2D) spin-wave mediated electron-electron interactions in antiferromagnets. At higher temperatures (40-160 K), the conductivity sigma cx bT 1/3, with coefficient b scaling with disorder strength kFl0 and the exchange interaction J, is consistent with the 3D incipient Anderson localization theories in the presence of dominant electron-magnon scattering. Moreover, the electron-magnon scattering time tau in was estimated based on the 2D to 3D dimensional crossover observed at about 40 K, which is consistent with theoretical results using the formula predicted by Muttalib et al. [Phys. Rev. B 91, 144410 (2015)]. Our work elucidates the critical role of electron-magnon interactions in modulating the incipient Anderson localization and thus influencing the quantum transport properties of disordered magnetic materials.

Unidirectional spin Hall magnetoresistance (USMR), arising from the interaction between nonequilibrium spin accumulation and magnetization, has been proposed as a simple two-terminal method for electrically detecting magnetic states in heavy-metal/ferromagnet bilayers. However, conventional spin polarization along the y direction restricts USMR to responding only to the transverse component of in-plane magnetization when a charge current is applied along the x direction. As a result, the electrical readout of longitudinal magnetic states via USMR has remained elusive. Here, we overcome this limitation by demonstrating an unconventional USMR induced by an x-polarized spin current in (001)-oriented epitaxial IrMn/FeNi bilayers, which enables electrical detection of the longitudinal magnetic state via USMR. By applying charge currents along different crystal orientations, we show that the x-polarized spin current exhibits a fourfold symmetry, consistent with the crystal mirror symmetry of (001)-oriented IrMn. This unconventional spin current further generates a large spin-orbit torque efficiency, an order of magnitude higher than that reported in antiferromagnetic Mn_{3}Pt and MnPd_{3} systems. Our Letter not only highlights the crucial role of intrinsic crystal symmetry in controlling spin polarization, but also extends the applicability of USMR to the electrical detection of longitudinal magnetization in two-terminal magnetic memory and spin-logic devices.

Unlike conventional approaches where topological order is statically fixed post-synthesis, we demonstrate that a single external knob-strain-can independently modulate topological order and functional responses in the Tc-adsorbed penta-hexa silicene (Tc_PH-Si) monolayer, with both properties governed by a single microscopic mechanism: momentum-space orbital-selective engineering of Tc-dxz_Si-px hybridization. Combining first-principles calculations and tight-binding models, we show that biaxial strain drives a complete topological pathway: C=1 (0) to C=0 (-2) to C = -1 (-3 to -4) to C = 0 metallic state (-6). This is exemplified by two pivotal states: a topologically critical point yet functionally optimal state at -2 strain (C=0) hosting a direct bandgap (0.17 eV) and d11 = 8.34 pm_V, and a topologically nontrivial but equally optimal state at -4 strain (C = -1) with d11 = 11.01 pm_V-three times that of MoS2. Berry curvature analysis reveals that functionality arises from local orbital hybridization strength, while topology originates from its global phase distribution. This establishes a new paradigm for materials design, transforming static functional materials into dynamically tunable quantum platforms.

Owing to magnetostrictive effects, nonlocal magnon transport in yttrium iron garnet (YIG) is often accompanied by phonon excitation. However, the influence of these phonons on magnon spin transport remains unclear. In our experiment, an external microwave field is applied to excite ferromagnetic resonance (FMR) in the YIG during nonlocal magnon transport measurements. We observe that an additional signal emerges in the thermal magnon transport. Angular-dependent measurements under varying magnetic fields further reveal that this additional signal is well described by our Landau-Lifshitz-Gilbert (LLG) simulation when enhanced magnetoelastic coupling is considered. This result indicates that the signal originates from the rotational lattice motion driven by magnetization precession, which generates phonons that subsequently couple to propagating magnons. This behavior contrasts with previously reported magnon-magnon scattering and parametric pumping, which occur strictly under resonant FMR conditions and require nonlinear excitation. Our results provide evidence that phonons actively participate in magnon spin transport and suggest viable opportunities for developing high-speed, phonon-assisted magnonic devices.

Resonance frequency of ferromagnets under external magnetic field is derived by solving the dynamic equation of magnetization with linear approximation in Cartesian coordinates, where the equilibrium direction of magnetization is along one of the axes. To resolve the long-standing mathematical singularity of the classic energy method at polar boundaries and provide a unified, laboratory-frame general analytical expression for complex non-collinear systems, the resonance frequency is formulated in terms of the free energy expressed in both Cartesian coordinates and spherical coordinates of magnetization. Magnetization, effective anisotropic filed and gyromagnetic ratio of the CoZr thin film with an in-plane uniaxial anisotropy are obtained by comparing the field dependence of the resonance frequency as an experimental attempt. The resonance frequency expressed with the spherical coordinates of magnetization in laboratory coordinates provides a more convenient way for understanding the fundamental quantities of ferromagnets.

Soft magnetic materials with high operating frequency and low power loss are crucial for electricity transmission and utilization. However, finding an effective method to improve the operating frequency while minimizing power loss in these materials remains a significant challenge. Herein, we synthesized the (Y1−xSmx)2Fe14B (0≤x≤1) compounds and introduced nitrogen atoms into their interstitial crystal sites via the gas–solid reaction, remarkably improving their operating frequency and reducing power loss. For the compounds with x = 0.15, the operating frequency increased from 1.7 to 5.5 MHz, with the imaginary part of relative permeability decreased from 6.1 to 1.6. The power loss decreased from 1607.7 to 664.1kW/m3, and loss separation indicated that eddy current loss Peddy was significantly suppressed by nitriding from 1397.7 to 547.9kW/m3. The conductivity decreased by approximately 43% by nitriding, from 9380.9 to 5359.0 S/m. These results demonstrate that tuning power loss through nitrogenation of rare-earth transition metal intermetallic compounds is an effective method for developing new high-frequency and low power loss soft magnetic materials.

Soft magnetic materials (SMMs) play a key role in the conversion of electric energy throughout the world. Developing MHz SMMs is a strategy for modern power systems supported by wide bandgap semiconductor devices. However, significant loss above hundreds of kHz in SMMs become a bottleneck for efficient energy conversion. Here, we report an effective approach to achieve a 250 kW/m3 low loss of Fe-Si composites at 3 MHz with 1.5 T saturation magnetization. By decreasing the particle size to 1 mu m in a core-shell structure or increasing the particle ratio of diameter/thickness to 100 in a layered structure, low loss particles with mechanism of coherent rotation modulated by the eddy current is formed in dense composites. Study shows that the decrease of loss primary comes from the collaborative decreasing of eddy current and excess loss. This approach opens a way to find MHz efficient SMMs for next-generation high-efficiency power systems.

The Stoner-Wohlfarth (SW) model describes coherent rotation of magnetization with uniaxial anisotropy. However, the traditional SW model can be analytically solved only for three specific directions, making it challenging to determine the direction of equilibrium magnetization in anisotropic ferromagnets under arbitrary fields. In this study, the uniaxial anisotropy energy in the SW model is extended to include a fourth-order term. By employing inverse function theory, an exact analytical solution for the equilibrium magnetization direction under any external field is derived. The impact of the fourth-order term on hysteresis loops is analyzed, showing increased coercivity for fields parallel to the easy axis and enhanced saturation fields for perpendicular ones. These results improve the understanding of static magnetism and provide a foundation for the quantitative analysis of magnetization scattering by electric and spin currents.

Due to the unique properties of compensated ferrimagnets, such as long spin coherence length, fast domain wall motion, and large spin-orbit torque, to manipulate ferrimagnetic order is crucial in spintronics. Here, we investigate the proximity effect of the two-dimensional van der Waals material WS2 on the interfacial ferrimagnetic order of CoTb. By increasing the thickness of WS2 from one to three layers, a dramatic increase of ferrimagnetic compensation temperature by 75 K is observed in CoTb. Based on a two-sublattice mean-field approximation, the increased compensation temperature is ascribed to the WS2-mediated tuning of the magnetic moments of the sublattices Tb and Co, rather than from the changed exchange interactions JCo-Co and JCo-Tb. First-principles calculations reveal that the tuned magnetic moments of the sublattices Tb and Co are realized through the proximity effect, where the charge transfer occurs between the interface of CoTb and WS2. Our study proposes a viable approach to manipulate the interfacial ferrimagnetic order through the proximity effect, which has potential applications for spintronic devices.

The Dzyaloshinskii-Moriya interaction (DMI) creates spin spirals and supports chiral magnetic structures, making it highly desirable for low-power spin-based memory, logic, and signal transmission. However, achieving nonvolatile control of the DMI remains a big challenge, especially at ferromagnetic interfaces under ambient temperatures. Here, we demonstrate ferroelectricity-controlled modulation of the DMI at Fe/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 interfaces using Brillouin light scattering (BLS). We observed a variation of more than 65% in DMI strength upon applying a strong electric field. This modulation is attributed to the interfacial Rashba spin-orbit coupling induced solely by ferroelectricity, which exhibits hysteresis-loop-like behavior in response to electric fields. The capability to modulate the DMI with external electric fields at room temperature positions vortexlike structures as promising candidates for chiral spintronics.

Although quantum corrections (e.g., weak localization and electron-electron interaction) due to disorder, coherence, and interactions have been intensively studied for decades, understanding the magnon-electron interaction effect on quantum transport properties in magnetic systems still remains a challenge. Thus, the role of spin waves in the quantum transport of magnetic materials has not yet been fully understood. Driven by the miniaturization of spintronics devices possibly moving forward to quantum transport dimensions, in this work, we investigate spin wave mediated quantum transport in epitaxial antiferromagnetic Cr2Al films. Temperature(T)-dependent conductance measurements reveal an additional linear T contribution in the low-temperature range (T < 30 K), which can be ascribed to the spin wave mediated electron-electron interactions in antiferromagnets. Brillouin light scattering confirms an antiferromagnetic resonance at near 80 GHz, consistent with the spin-flop field H-SF similar to 30 kOe derived from magnetoresistance measurements. Furthermore, the anomalous Hall effect in 2 nm Cr2Al films exhibits G(AH) proportional to ln T and G(AH) proportional to G(0.9) (xx) (T < 100 K), indicating that electron-electron Coulomb interactions contribute to the anomalous Hall effect through the extrinsic skew scattering mechanism, while the spin wave mediated electron-electron interactions show no contribution. These results provide critical insights into the effect of spin waves on the quantum transport properties of magnetic materials.

The solutions of the Landau–Lifshitz–Gilbert (LLG) equation reveal nonlinear effects in electron spin dynamics. Here, the nonmonotonic power dependence of the electron paramagnetic resonance (EPR) signal intensity is derived by solving the LLG equation. The analytical solutions of a spin moment are obtained for linearly polarized microwaves with any power. A tendency of susceptibility from linear to nonlinear is exhibited with increasing microwave power. Both low- and high-power dependences of EPR signal intensity of standard sample 1,3-bisdiphenylene-2-phenylallyl are well explained by the tendency. These findings provide valuable insights into nonlinear behavior of spin dynamics and the quantitative analysis of paramagnetic centers.