Extending the scope and understanding of all-optical magnetization switching in Gd-based alloys by controlling the underlying temperature transients

We use the thickness of Cu layers to control all -optical switching of magnetization in adjacent Gd24(Fe90Co10)76 films. While increasing the Cu thickness from 5 to 900 nm has no effect on the switching threshold, it significantly enlarges the fluence and pulse duration at which multiple domains emerge. Having shown that thermally activated multidomain formation limits the maximum fluence and pulse duration for controlled switching, we demonstrate that continuous magnetization reversal precedes multidomain formation in Gd18Dy4Co78 films excited with fluences slightly larger than the multidomain threshold.