Abstract
The magnetization dynamics of a ferromagnet subjected to an electrical current are described by an extension of the Landau-Lifshitz-Gilbert equation that contains two additional terms, the adiabatic and nonadiabatic spin-transfer torques. First-principles calculations of the nonadiabatic spin-transfer torque parameter for bcc iron and fcc nickel show that is related to and typically of the same order as , the damping constant, but is distinct from it. Calculations as a function of the ratio of spin-dependent scattering rates show that (1) the minimum of the damping constant as a function of scattering rate does not change significantly, and (2) when the polarization of the current approaches zero, can become large but the implied domain-wall velocity does not.
- Received 6 October 2011
DOI:https://doi.org/10.1103/PhysRevB.84.224412
©2011 American Physical Society