Guoqiang Yu

Power-law transformations are widely used in edge perception, where compact implementations must balance numerical precision, circuit resources, and device variability. Here, we demonstrate a stochastic power-law architecture based on spin–orbit-torque magnetic tunnel junctions (SOT-MTJs). An event-driven feedback loop adjusts the write voltage to regulate the probability of an all-1 event in an n-bit block. Under the fixed-point sampling model, this establishes a switching probability p = b1/n, from which m-bit event statistics yield the power-law target bm/n. Online probability locking removes the need for offline per-device probability-voltage characterization or stored calibration tables. Measurements on W-based SOT-MTJs, combined with digital analysis of the acquired bitstreams, demonstrate representative power-law operations with absolute deviations of 0.003 or less at the reported precision, as well as parallel decoding of multiple exponents from one source. A 4-bit gamma-correction example preserves dark-region image detail and reaches approximately 35 dB peak signal-to-noise ratio relative to the theoretical gamma-domain reference near 1000 raw samples. A 5 Oe device-level field perturbation and a joint ±90% simulation centered on the measured parameter means of 25 devices examine adaptation and the safe voltage operating boundary under the tested conditions. These results establish a nonlinear computing primitive with accuracy controlled by sampling depth and an operating point maintained through feedback.

Realizing room‐temperature out‐of‐plane spin currents remains a key challenge for low‐power perpendicular spin–orbit torque devices. Oxides with strong spin–orbit coupling are highly desirable spin sources for spintronic applications, and RuO ₂ has recently attracted widespread attention owing to its excellent spin transport properties. However, the generation of out‐of‐plane spin polarization is limited to specific crystallographic orientations, restricting materials design flexibility and practical device integration. Here, we demonstrate that interfacial magnetic coupling between RuO ₂ and an insulating ferromagnet can provide an effective route to circumvent this constraint. In RuO ₂ (110)/CoFe ₂ O ₄ heterostructures, the interfacial coupling induces a net magnetization component in RuO ₂ tilted toward the film plane, giving rise to a robust anomalous Hall effect up to room temperature. Spin‐torque ferromagnetic resonance measurements reveal a high spin–orbit torque efficiency of ∼0.18 in CoFe ₂ O ₄ ‐buffered RuO ₂ , representing a sixfold enhancement compared with bare RuO ₂ (110) films. Notably, the spin tilting of RuO ₂ generates a distinct z‐polarized spin‐current component with a torque efficiency of ∼0.014, indicating that interfacial magnetic engineering enables out‐of‐plane spin polarization in RuO ₂ (110). These results suggest interfacial magnetic modulation as a versatile strategy for realizing room‐temperature anomalous Hall effects and efficient spin–orbit torques in strongly spin–orbit coupled oxide heterostructures, opening new opportunities for oxide‐based spintronic applications.

Magnetic phase transitions provide a powerful means of reconstructing magnetic order, yet how such reconstruction can be exploited to generate large and highly responsive lattice deformation remains insufficiently understood. Here, we demonstrate that a field-induced collective spin-reorientation (SR) transition in the kagome ferrimagnet TbMn6Sn6 enables large hysteresis-free magnetostriction with high strain sensitivity. Magneto-optical Kerr microscopy reveals a concomitant reconstruction of stripe domains across the same transition regime, providing real-space evidence for collective magnetic reorganization. Relativistic first-principles calculations capture the orientation-dependent lattice response and further indicate that reorientation of the ferrimagnetic axis selectively modifies the intralayer and interlayer magnetic exchange interactions. Our work establishes field-induced magnetic reconstruction as an effective strategy for achieving large hysteresis-free magnetostriction, providing a framework for designing transition-enabled magnetoelastic functionalities in kagome magnets and correlated magnetic materials.

Acoustic spintronics, an emergent field at the nexus of spintronics and acoustics, harnesses lattice strain and rotation from acoustic waves to manipulate the spin degree of freedom. This makes a departure from conventional spintronics, which typically relies on charge currents to generate spin currents (SCs), and enables low-power, non-contact, and long-distance manipulation and transmission of spin information, opening new avenues for advanced spintronic applications. This review systematically surveys recent progress, constructing a comprehensive framework from the magneto–acoustic coupling mechanisms and SC generation to their electrical detection. We elucidate the physical pictures of various magneto–acoustic coupling mechanisms, clarifying how dynamic strain, lattice rotation, and vorticity fields distinctly mediate spin dynamics. We systematically introduce the methods for generating SCs in diverse material systems, namely acoustic spin pumping, spin-vorticity coupling, and the acoustic spin Hall effect. Common electrical detection techniques are also summarized, providing the theoretical basis to disentangle complex coexisting signals. Finally, we provide an outlook on future research directions and the potential application landscape of this emerging field.

The collective precession of magnetization manifests itself as magnon modes. These modes are governed by complex-valued vectorial eigenfunctions, which have remained experimentally challenging to observe. Here we introduce X-ray magnetic vector chronoscopy (XMVC), a time-resolved resonant scattering method that reconstructs the full magnetization dynamics with angular resolution of 0.1° (±0.01°). Applied to a synthetic antiferromagnetic multilayer (Si/NiFe (8 nm)/Ru (0.8 nm)/CoFeB (5.5 nm)), XMVC enables magnon state tomography, by directly measuring the nanoscale vectorial eigenfunctions of hybridized modes arising from magnon–magnon coupling. This approach provides full access to the system’s non-Hermitian Hamiltonian, revealing the complex-valued coupling strengths and non-orthogonal eigenbases. These results establish XMVC as an experimental platform for studying nanoscale spin systems by extracting the eigenfunctions of the system.

The development of energy-efficient spin–orbit torque devices hinges on realizing field-free switching of perpendicular magnetization with minimal power consumption. Here, we demonstrate robust field-free switching of perpendicular magnetization at room temperature, enabled by out-of-plane spins generated in the Weyl semimetal NbIrTe₄. The critical switching current density is 3.6 × 10⁶ A/cm², corresponding to the lowest power consumption reported among intrinsic low-crystal-symmetry materials, 16 times lower than that of WTe₂ and 4 times lower than that of TaIrTe₄. The switching polarity remains stable up to an in-plane magnetic field of 19 mT, confirming the robustness of the field-free operation against magnetic perturbations. Loop-shift measurements and first-principles calculations consistently reveal a large out-of-plane spin Hall conductivity in NbIrTe₄, σ_s,z ≈ 2.61 × 10⁴ (ℏ/2e)(Ω·m)⁻¹, responsible for the highly efficient and stable magnetization switching. These findings position NbIrTe₄ as a compelling member of the emerging class of low-symmetry materials and offer a promising pathway toward the development of energy-efficient, all-electric spin–orbit torque devices.

Bloch points and transverse walls can serve as topological boundaries within a magnetic domain wall. Here, we investigate the stability and dynamics of these topological boundaries for potential spintronic applications. Using micromagnetic simulations, we reveal the coexistence regimes of Bloch points and transverse walls in thin films with perpendicular magnetic anisotropy. An external in-plane field enables reversible transitions between these states through boundary-mediated Bloch point nucleation and annihilation processes. Under spin-transfer torque, transverse walls exhibit transverse drift and deformation. In contrast, Bloch points move strictly along the domain wall without transverse deflection and feature a Walker breakdown threshold an order of magnitude higher than conventional domain walls. Our findings establish a device concept where binary states correspond to in-plane magnetization orientations separated by mobile topological boundaries, offering new opportunities for spintronic architectures.

Magnonic frequency combs, characterized by a series of discrete frequency lines, have emerged as a promising frontier in magnon spintronics, with potential applications in advanced information processing and sensing technologies. Although the three-magnon scattering process is widely recognized as a fundamental mechanism for generating these combs, its experimental realization has remained challenging due to the high threshold power and strict conservation of momentum and energy. In this work, we propose a novel mechanism for the stimulated generation of magnonic frequency combs that overcomes these limitations. Our approach offers precise and efficient control over key comb properties, including spacing between spectral lines and the number of lines, marking a significant advancement in the field. We substantiate this mechanism through a robust combination of theoretical modeling, micromagnetic simulations, and experimental validation. This study not only demonstrates the feasibility of our method but also opens new pathways for integrating magnonic frequency combs into practical spintronic devices.

Magnetic random-access memory (MRAM) provides a promising candidate for the next-generation memory technology with high-energy efficiency and fast operation speed. Spin splitting band structure in nonrelativistic collinear antiferromagnet with de-coupled crystal and spin symmetry provides a unique way for the flexible and efficient control of the polarization and flow directions of the spin current. Here, by integrating the potential altermagnetic (101)-RuO₂ writing channel with the magnetic tunnel junction (MTJ) device, we demonstrate the all-electrical field-free altermagnetic spin splitting torque (SST)-driven switching of the perpendicular-MTJ in the 3-terminal altermagnetic SST-MRAM device, with the tilted spin polarization and the transversal flow of the spin current. The z-spin torque is further characterized by the altermagnetic SST-induced shift of the magnetic hysteresis loop, and the field-free altermagnetic SST-driven magnetic domain switching of the recording layer is directly observed by the magneto-optic Kerr effect (MOKE) microscope. Our research establishes groundwork for advancing the development of the altermagnetic SST-MRAM, paving the way for the future all-electrical, energy-efficient and high-endurance MRAM applications with separated writing/reading channels.

Ensuring authentication, data security, and privacy has become critically important with the rise of Internet of Things (IoT) systems. Physical unclonable functions (PUFs) employ the intrinsic physical randomness of materials to generate unique, nonreplicable outputs, ensuring device authenticity and protection against cloning. Although silicon‐based PUFs have significantly advanced, developing practical and cost‐effective solutions for resource‐constrained embedded systems remains challenging. This study demonstrates a reconfigurable PUF design that leverages spontaneously formed labyrinth domain patterns in magnetic thin films as a high‐entropy source, without requiring any external stimuli or control. The resulting PUFs display nearly ideal performance in uniqueness, uniformity, bit‐aliasing, and robustness, underscoring their practicality and reliability. These PUFs demonstrate high indivisibility in linear feature spaces and robustness against compromising the security or functionality of machine learning. More importantly, the electrical readout of domain‐based PUF signals is demonstrated using magnetic tunnel junctions and propose an architecture for integrating the PUF system with existing silicon‐based circuits. Overall, the proposed PUF system offers a practical and innovative solution for advanced anti‐counterfeiting measures and secure device identification.