The role of intermixing in all-optical switching of synthetic-ferrimagnetic multilayers

We present a theoretical study of single-pulse all-optical switching (AOS) in synthetic-ferrimagnetic multilayers. Specifically, we investigate the role of interface intermixing in switching Co/Gd bilayers. We model the laser-induced magnetization dynamics in Co/Gd bilayers using the microscopic three-temperature model for layered magnetic systems. Exchange scattering is included, which mediates angular momentum transfer between the magnetic sublattices. In this work, each layer is represented by one atomic monolayer of a GdCo alloy with an arbitrary Co concentration, allowing Co/Gd bilayers with an intermixed interface to be modelled. Our results indicate that within the model intermixing of the Co/Gd interface reduces the threshold fluence for AOS significantly. We show that intermixing does not qualitatively affect the switching mechanism and leads to an increase of the propagation speed of the switching front.