“…This is the reason why alloptical switching in ferromagnets attracts great attention. Ferromagnets, such as Pt/Co/Pt multilayers (Lambert et al, 2014;Hadri et al, 2016a;Hadri et al, 2016b;Medapalli et al, 2017;Parlak et al, 2018;Quessab et al, 2018;Chakravarty et al, 2019;Kichin et al, 2019;Cheng et al, 2020) and granular FePt alloys (Lambert et al, 2014;Takahashi et al, 2016;John et al, 2017), have recently shown all-optical helicity-dependent switching (AO-HDS), magnetization switching depending on the circular polarization of the optical excitation pulses. However, AO-HDS generally requires at least tens and usually hundreds of laser pulses for full switching (Kichin et al, 2019).…”