Motion of a magnetic domain wall traversed by fast-rising current pulses

Abstract

A Bloch wall is predicted to undergo finite displacements when traversed by a current pulse with short rise time ≤20 ns and long fall time, in thin films of metallic ferromagnets. In Ni–Fe films of thickness 85–150 nm, pulses with peak current density ≂1×107 A/cm2 are expected to induce wall displacements of order 0.1–1 μm. This effect originates from the s-d exchange interaction. It is phenomenologically similar to the well-known ‘‘wall streaming’’ motion of Bloch walls subjected to fast-rising pulses of hard-axis magnetic field. The effect is related to the existence of a novel, current-induced, term in the expression for the momentum of a magnetic domain wall.