Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems

Abstract: Spin-orbit coupling in inversion-asymmetric magnetic crystals and structures has emerged as a powerful tool to generate complex magnetic textures, interconvert charge and spin under applied current, and control magnetization dynamics. Current-induced spin-orbit torques mediate the transfer of angular momentum from the lattice to the spin system, leading to sustained magnetic oscillations or switching of ferromagnetic as well as antiferromagnetic structures. The manipulation of magnetic order, domain walls and skyrmions by spin-orbit torques provides evidence of the microscopic interactions between charge and spin in a variety of materials and opens novel strategies to design spintronic devices with potentially high impact in data storage, nonvolatile logic, and magnonic applications. This paper reviews recent progress in the field of spin-orbitronics, focusing on theoretical models, material properties, and experimental results obtained on bulk noncentrosymmetric conductors and multilayer heterostructures, including metals, semiconductors, and topological insulator systems. Relevant aspects for improving the understanding and optimizing the efficiency of nonequilibrium spin-orbit phenomena in future nanoscale devices are also discussed.

• The paper reviews how inversion asymmetry in magnetic systems generates efficient spin-orbit torques to control magnetization dynamics.
• It presents strong numerical evidence from bulk conductors, multilayer heterostructures, and topological insulators to quantify torque efficiency.
• The study outlines theoretical insights and future directions for developing high-density memory and logic devices in spintronics.

Current-induced Spin-Orbit Torques in Ferromagnetic and Antiferromagnetic Systems

The exploration of current-induced spin-orbit torques (SOTs) has significantly advanced our understanding of spintronics and its applications in modern data storage and logic devices. This paper provides a comprehensive review of how spin-orbit coupling in inversion-asymmetric magnetic structures facilitates the generation of SOTs, ultimately controlling magnetization dynamics and enabling innovative device architectures.

Overview of the Paper

The paper discusses the phenomena of spin-orbit torques, which arise from the interaction of spin and charge currents in systems where inversion symmetry is broken. These torques are vital for the manipulation of magnetic textures in ferromagnetic and antiferromagnetic materials. They provide pathways for efficient switching and oscillation of magnetic states and open up new strategies for designing devices with potential applications in data storage, nonvolatile logic, and magnonic applications.

Strong Numerical Results and Claims

The paper presents substantial numerical results that highlight the role of spin-orbit torques in both ferromagnetic and antiferromagnetic systems. Specifically, the efficiencies of these torques are discussed in the context of various materials such as bulk noncentrosymmetric conductors, multilayer heterostructures, and topological insulator systems. These values are crucial for understanding how effective these torques can be in practical applications such as magnetic memories and nano-oscillators.

Theoretical and Practical Implications

From a theoretical perspective, SOTs provide a deeper insight into the microscopic interactions between charge and spin, particularly in systems lacking inversion symmetry. This understanding aids in optimizing the efficiency of spin-orbit phenomena at the nanoscale. Practically, successfully harnessing SOTs could lead to transformative breakthroughs in high-density memory storage, magnetic logic devices, and spin wave-based technologies.

Future Development in Spintronics

The research suggests several future directions, including enhancing the spin torque efficiency through material design and understanding the interplay between interfacial and bulk scattering mechanisms. Another avenue for development is the exploration of topological materials, which promise high spin-to-charge conversion efficiency. The potential to integrate antiferromagnetic materials for robust and efficient devices also presents a compelling research direction.

In conclusion, the paper offers an insightful overview of the current understanding and potential of spin-orbit torques. It underscores the substantial progress made in this field and how these advances can lead to groundbreaking applications in the field of spintronics.