Theory of magnetic domain dynamics in uniaxial materials

摘要

We have calculated the total Lagrangian and Rayleigh dissipation functions for an isolated domain of arbitrary cross section in an infinite plate with perpendicular anisotropy. Variation of these functions yields a set of coupled equations describing the motion of the center of mass and the boundaryR(phgr;) (in general noncircular) of the domain. We neglectzdependence and assumedgr;/R≪1where dgr; is the wall ``thickness''. The theory is applicable for applied field variations of arbitrary speed and magnitude. For uniform field pulses, the equations reduce to the Callen‐Josephs theory in the weak‐pulse limit. For pulses >2pgr;Ms/agr;, where agr; is the Gilbert parameter, the behavior again tends to be linear with, generally, a greatly reduced apparent mobility, while in the transition region 2pgr;Msagr;