Non-Adiabatic Spin Transfer Torque in Real Materials

Published

March 16, 2009

Author(s)

Ion Garate, Keith Gilmore, Mark D. Stiles, Allan H. MacDonald

Abstract

The motion of simple domain walls and of more complex magnetic textures in the presence of a transport current is described by the Landau-Lifshitz-Slonczewski (LLS) equations. Predictions of the LLS equations depend sensitively on the ratio between the dimensionless material parameter β which characterizes non-adiabatic spin-transfer torques and the Gilbert damping parameter α. This ratio has been variously estimated to be close to 0, close to 1, and large compared to 1. By identifying β as the influence of a transport current on α, we derive a concise, explicit and relatively simple expression which relates β to the band structure and Bloch state lifetimes of a magnetic metal. Using this expression we demonstrate that intrinsic spin-orbit interactions lead to intra-band contributions to β which are often dominant and can be (i) estimated with some confidence and (ii) interpreted using the ``breathing Fermi surface'' model.

Citation

Physical Review B (Condensed Matter and Materials Physics)

Volume

79

Issue

10

Pub Type

Journals

Download Paper

Local Download

Keywords

Spin-transfer torque, Magnetic damping, Magnetization dynamics, Adiabatic, Spin-orbit coupling, Domain wall, Spin current

Citation

Garate, I. , Gilmore, K. , Stiles, M. and MacDonald, A. (2009), Non-Adiabatic Spin Transfer Torque in Real Materials, Physical Review B (Condensed Matter and Materials Physics), [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=901198 (Accessed September 18, 2024)