Single shot ultrafast all optical magnetization switching of ferromagnetic Co/Pt multilayers

TL;DR

This paper presents a novel method enabling single-shot, all-optical, ultrafast magnetization switching in ferromagnetic Co/Pt multilayers within 7 picoseconds, overcoming previous limitations of partial and repeated pulsing.

Contribution

The authors develop a general technique for complete, single-shot optical switching of ferromagnetic materials, demonstrated on Co/Pt multilayers, significantly advancing ultrafast magnetic control.

Findings

Achieved single-shot switching within 7 ps

Demonstrated switching in Co/Pt multilayers

Expanded potential for ultrafast magnetic applications

Abstract

In a number of recent experiments, it has been shown that femtosecond laser pulses can control magnetization on picosecond timescales, which is at least an order of magnitude faster compared to conventional magnetization dynamics. Among these demonstrations, one material system (GdFeCo ferromagnetic films) is particularly interesting, as deterministic toggle-switching of the magnetic order has been achieved without the need of any symmetry breaking magnetic field. This phenomenon is often referred to as all optical switching (AOS). However, so far, GdFeCo remains the only material system where such deterministic switching has been observed. When extended to ferromagnetic systems, which are of greater interest in many technological applications, only a partial effect can be achieved, which in turn requires repeated laser pulses for full switching. However, such repeated pulsing is not only energy hungry, it also negates the speed advantage of AOS. Motivated by this problem, we have developed a general method for single-shot, picosecond timescale, complete all optical switching of ferromagnetic materials. We demonstrate that in exchange-coupled layers of Co/Pt and GdFeCo, single shot, switching of the ferromagnetic Co/Pt layer is achieved within 7 picoseconds after irradiation by a femtosecond laser pulse. We believe that this approach will greatly expand the range of materials and applications for ultrafast magnetic switching.