A GENERAL-MODEL FOR POWER DISSIPATION BY DOMAIN-WALL MOVEMENT IN THINFERROMAGNETIC-FILMS

In this work we present a model for magnetic domain wall (DW) dynamics in metallic ferromagnets with uniaxial anisotropy. The model allows u s to consider both viscous and eddy current dampings. While the latter mechanism involves only one degree of freedom - the coordinate of the DW, the former involves all degrees of freedom of the spins in magnet ic domains and in DW's. The structure of the DW itself must then be co nsidered, the conjecture used allowing one to describe the spin preces sions which may appear in low quality factor Q materials. The model bu ilt is nonlinear, allowing one to deal with the set of complex suscept ibilities characterizing the response to an ac drive field in strongly nonlinear circumstances, and has a general character, due to the norm alized quantities used. In this work we analyze the susceptibility and the dissipated power spectra as functions of a de transversal field, which can be treated only by this kind of models. We show that the vis cous damping can become comparable to eddy current damping when preces sions are excited.