Abstract
Ultrafast optical heating of the electrons in ferrimagnetic metals can result in all-optical switching (AOS) of the magnetization. Here we report quantitative measurements of the temperature rise of GdFeCo thin films during helicity-independent AOS. Critical switching fluences are obtained as a function of the initial temperature of the sample and for laser pulse durations from 55 fs to 15 ps. We conclude that nonequilibrium phenomena are necessary for helicity-independent AOS, although the peak electron temperature does not play a critical role. Pump-probe time-resolved experiments show that the switching time increases as the pulse duration increases, with 10 ps pulses resulting in switching times of ps. These results raise new questions about the fundamental mechanism of helicity-independent AOS.
- Received 2 June 2016
- Revised 5 September 2016
DOI:https://doi.org/10.1103/PhysRevB.94.184406
©2016 American Physical Society