Criteria to observe single-shot all-optical switching in Gd-based ferrimagnetic alloys

TL;DR

This paper establishes criteria for observing single-shot all-optical helicity-independent switching in Gd-based ferrimagnetic alloys by analyzing laser fluence thresholds and magnetic parameters, aiding the design of ultrafast spintronic devices.

Contribution

It defines the key laser fluence thresholds and magnetic conditions necessary for AO-HIS in Gd-based ferrimagnetic alloys, advancing understanding of the switching mechanism.

Findings

Two distinct laser fluence thresholds are identified: FSwitch and FMulti.

The behavior of these thresholds varies with material properties and laser pulse duration.

Angular momentum transfer from Gd sublattice explains the experimental results.

Abstract

Single-shot all-optical helicity-independent switching (AO-HIS) induced by a femto-second laser pulse has been mainly reported in Gadolinium based rare earth-transition metal (RE-TM) alloys such as GdFeCo or GdCo, but the mechanism leading to magnetization switching is a hotly debated topic. Here, we elaborate on a large number of GdyRE1-x-yCox (RE = Dy, Tb, Ho) alloys to tune various magnetic parameters in order to define what the criteria are for observing AO-HIS in such systems. The state diagrams show that two laser fluences thresholds must be considered:the fluence which induces the single laser pulse switching (FSwitch) and the fluence at which the material breaks into a multi-domain state (FMulti). Those two fluences are shown to behave very differently as a function of the material properties and the laser pulse duration. Taking into account the parameters defining the conditions for which multi-domain states are created and considering only the angular momentum transfer from the Gd sublattice to the rest of the system explains in large our experimental results. The importance of the compensation in the ferrimagnetic alloys is also discussed. We believe the defined criteria will be an important tool for designing new ultra-fast spintronic devices based on all optical switching.