Joule heating and current-induced domain wall motion

Abstract

We investigate numerically and experimentally the Joule heating produced by current pulses and its contribution to current-induced domain wall (DW) motion in a (Ga,Mn)As ferromagnetic semiconductor. Different thermal coupling between tracks and substrates are explored. A direct contact leads to a logarithmic transient temperature rise and a stationary state determined by the substrate thickness. The introduction of a low thermal conducting (Ga,In)As interlayer produces an additional temperature rise whose time variation and magnitude are analyzed. Experimentally, the measured temperature rises present a good agreement with predictions over more than four orders of magnitude in time for values of the heat conductivity and of the heat capacity close to those reported in the literature. The Joule heating is shown to produce non-linearities in the domain wall velocity versus current density characteristics. A correction of Joule heating is proposed and permits the identification of the flow regimes from a comparison of domain-wall dynamics in tracks presenting different pinning characteristics.