Abstract
The author has considered the dynamics of the interaction of a 180 degrees ferromagnetic domain wall with a planar defect characterised by an abrupt change in both the magnetic anisotropy and exchange energies. It is shown that the minimum velocity for the soliton or domain wall to penetrate the barrier is proportional to the fractional change in the characteristics of the medium as defined by the defect, the maximum or critical domain wall velocity, and the hyperbolic tangent of the ratio of defect to domain wall width. For iron, the author computes the theoretical value of approximately 3000 cm s-1. The resonant domain wall oscillation frequency due to a grain boundary in iron is computed as approximately 400 MHz in good agreement with typical experimental values of approximately 500 MHz.