Landau-Lifshitz or Gilbert damping? That is the question
Abstract
In their seminal 1935 paper on magnetics, Landau and Lifshitz (LL) proposed a form for magnetization damping. In 1955 Gilbert proposed another form, introducing a dimensionless parameter α. We derive LL damping using the theory of irreversible thermodynamics, summarize an unbiased Langevin theory of fluctuations that yields LL damping, and argue that inhomogeneous broadening might explain the nonresonance data that led Gilbert to formulate his theory. LL versus Gilbert damping takes on special relevance in the context of bulk spin transfer torque and bulk spin pumping, where the form of damping affects the values of the "adiabatic" and "nonadiabatic" terms. We argue that the adiabatic and nonadiabatic terms are dissipative and reactive, respectively.
- Publication:
-
Journal of Applied Physics
- Pub Date:
- April 2009
- DOI:
- 10.1063/1.3077204
- Bibcode:
- 2009JAP...105gD315S
- Keywords:
-
- 75.60.Ej;
- 75.50.Dd;
- Magnetization curves hysteresis Barkhausen and related effects;
- Nonmetallic ferromagnetic materials