Two magnon bound state causes ultrafast thermally induced magnetisation switching

TL;DR

This paper reveals that thermally induced magnetisation switching in ferrimagnetic materials is caused by the excitation of two magnon bound states, enabling precise prediction and potential design of materials for ultrafast memory devices.

Contribution

It identifies the microscopic mechanism of thermally induced magnetisation switching as two magnon bound states, combining computational and analytic methods.

Findings

Switching is driven by two magnon bound states.

Properties of these states depend on material factors.

Mechanism enables prediction and design of new materials.

Abstract

There has been much interest recently in the discovery of thermally induced magnetisation switching, where a ferrimagnetic system can be switched deterministically without and applied magnetic field. Experimental results suggest that the reversal occurs due to intrinsic material properties, but so far the microscopic mechanism responsible for reversal has not been identified. Using computational and analytic methods we show that the switching is caused by the excitation of two magnon bound states, the properties of which are dependent on material factors. This discovery allows us to accurately predict the switching behaviour and the identification of this mechanism will allow new classes of materials to be identified or designed to use this switching in memory devices in the THz regime.