Regensburg 2007 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 24: Spindynamics / Switching II

MA 24.7: Vortrag

Donnerstag, 29. März 2007, 11:45–12:00, H23

Breathing Fermi surface model for noncollinear magnetization: A generalization of the Gilbert equation — •Daniel Steiauf and Manfred Fähnle — Max-Planck-Institut für Metallforschung, Heisenbergstraße 3, 70569 Stuttgart

Within the breathing Fermi surface model the damping of the magnetization dynamics is related to the change of the Fermi surface with changing magnetic configuration, given by the orientations of the atomic magnetic moments: This change requires a scattering of the electrons among the single-electron states in reciprocal space, and this in turn requires time. For a uniform cooperative rotation of all magnetic moments the change of the Fermi surface results from spin-orbit coupling. In this case the theory yields a Gilbert-type equation of motion for the magnetization with the damping scalar of the original Gilbert equation replaced by a damping matrix which depends on the momentary orientation of the magnetization. The change of a noncollinear magnetization configuration leads to an even stronger change of the Fermi surface resulting from the interatomic exchange interactions. The damping then is described by a damping matrix which is different for different sites and which depends on the momentary magnetization configuration of the whole system, i.e., the equation of motion is nonlocal.