Spin Angular Momentum Transfer in Nano-Magnets

Jonathan Z. Sun, PhD
IBM-MagIC MRAM Alliance
IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598
MagIC Technologies, Milpitas, CA 95035

Abstract - Since its discovery a decade or so ago, spin angular momentum transfer torque (STT, or spin-torque) has been shown to play an important role in magnetotransport and magnetodynamics in nanomagnets. In small structures below ~ 100nm in size, STT provides an effective means of manipulation and control of magnetic states, leading to new technology developments in solid-state memories (STT MRAM), compact microwave oscillators, and potential interests for spin-based low power high performance logic devices. In this talk, I will review the basic scientific findings of spin-torque, relating experimental observations to simple quantitative analysis. Issues discussed include the basic physics of a spin-current-induced torque on a nanomagnet, and device concepts such as STT switches and oscillators, using as examples the familiar two-terminal spin-valves and magnetic tunnel-junctions, as well as the more recently demonstrated three-terminal spin-based transistors. I will also review the progress of various efforts, well under way, of technology development in applications of spin-torque, with an emphasis on STT MRAM.