Theory of domain wall dynamics in bubble films with coercivity

Abstract

We propose a simple, obvious model for coercivity, that is in agreement with the experimental data. The problem of domain wall (DW) displacement under the influence of pulsed magnetic field is solved for the general case, when both the pulse amplitudes and durations are different. The cases of infinitesimally small and finite pulse front durations are considered. It is shown that the character of the DW dynamics character is defined by the sign of the parameter λ 2=( β m ) 2− 4k m , where m is the mass of the DW, and β and k are viscous friction and stiffness coefficients, respectively. In the chosen model the remaining shift of the DW (the difference between the DW coordinates after the influence of two equal and oppositely directed magnetic field pulses) is connected only with the coercivity. In the demonstrated procedure, every reasonable form of both magnetic and coercive fields may be used.