Current-induced torques in magnetic materials

• Published in: Nature materials Vol. 11; no. 5; pp. 372 - 381
• Main Authors: Brataas, Arne, Kent, Andrew D., Ohno, Hideo
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 23-04-2012; Nature Publishing Group
• Subjects: 639/301/1005; 639/301/119/995; 639/301/119/997; Angular momentum; Biomaterials; Chemistry and Materials Science; Condensed Matter Physics; Electric currents; Joints; Magnetic materials; Magnetism; Magnetization; Materials Science; Nanotechnology; Optical and Electronic Materials; Orientation; review-article; Semiconductors; State of the art; Stores; Transport
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/nmat3311

Spin-transfer torque is the rotation that a spin-polarized current induces on the magnetization of the solid it flows through. The way in which currents generate torques in a wide variety of magnetic materials and structures is discussed in this Review, as well as recent state-of-the-art demonstrations of current-induced-torque devices that show great promise for enhancing the functionality of semiconductor devices.
The magnetization of a magnetic material can be reversed by using electric currents that transport spin angular momentum. In the reciprocal process a changing magnetization orientation produces currents that transport spin angular momentum. Understanding how these processes occur reveals the intricate connection between magnetization and spin transport, and can transform technologies that generate, store or process information via the magnetization direction. Here we explain how currents can generate torques that affect the magnetic orientation and the reciprocal effect in a wide variety of magnetic materials and structures. We also discuss recent state-of-the-art demonstrations of current-induced torque devices that show great promise for enhancing the functionality of semiconductor devices.