Physical Review B 79(10), 104416 (2009).
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 nonadiabatic spin-transfer torques and the Gilbert damping parameter α. This ratio has been variously estimated to be close to zero, close to one, and large compared to one. 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 intraband contributions to β which are often dominant, and can be (i) estimated with some confidence and (ii) interpreted using the "breathing Fermi-surface" model.
Keywords: band structure, damping, Fermi surface, ferromagnetic materials, gallium arsenide, magnetic domain walls, magnetic semiconductors, manganese, spin-orbit interactions
Center for Nanoscale Science and Technology
NIST is an agency of the U.S. Department of Commerce
Website Comments:epgwebmaster@nist.gov