Abstract
We present an experimental and theoretical investigation of all-optical switching by single femtosecond laser pulses. Our experimental results demonstrate that, unlike rare-earth transition-metal ferrimagnetic alloys, can be switched in the absence of a magnetization compensation temperature, indicative for strikingly different switching conditions. In order to understand the underlying mechanism, we model the laser-induced magnetization dynamics in Co/Gd bilayers and GdCo alloys on an equal footing, using an extension of the microscopic three-temperature model to multiple magnetic sublattices and including exchange scattering. In agreement with our experimental observations, the model shows that Co/Gd bilayers can be switched for a thickness of the Co layer far away from compensating the total Co and Gd magnetic moment. We identify the switching mechanism in Co/Gd bilayers as a front of reversed Co magnetization that nucleates near the Co/Gd interface and propagates through the Co layer driven by exchange scattering.
- Received 31 July 2019
- Revised 16 October 2019
DOI:https://doi.org/10.1103/PhysRevB.100.220409
©2019 American Physical Society