Computer simulation of domain wall motion in a magnetic strip line with submicron width

The dynamics of magnetization reversal in a very narrow ferromagnetic wire was investigated by micromagnetic computer simulation. The calculation was performed both for an isolated finite-length wire and for an infinitely lon g wire which contained a domain wall in a portion. In the former calculatio n, a remanent equilibrium domain configuration was, at first, derived from a uniformly magnetized configuration. Then a reversal field was applied alo ng the wire so as to nucleate and move the domain walls. A reversal field o f a hundred and several tens Oe was necessary to nucleate a moving wall. It was found that the head of the moving wall had the shape of a wedge and th at the wall dynamically changed its structure while moving. In the latter c alculation, the mechanism of wall motion and the wall velocity at lower dri ving fields were evaluated. When the driving field was small enough, the wa ll moved with keeping its magnetic structure. The wall velocity became high er with increasing the width or decreasing the thickness of the wire. In th e application of higher fields, however, the wall structure changed dynamic ally, and the wall velocity was almost twice as large as that in the steady -state motion.