Manipulating exchange bias using all-optical helicity-dependent switching

TL;DR

This paper demonstrates all-optical control of exchange bias in antiferromagnetic/ferromagnetic heterostructures using laser helicity, enabling magnetic state switching without external magnetic fields, with potential spintronic applications.

Contribution

It introduces a novel method for controlling exchange bias via all-optical helicity-dependent switching in antiferromagnetic materials, expanding the understanding of optical magnetic manipulation.

Findings

Controlled switching of exchange bias sign by laser helicity.

Quantified influence of laser fluence and pulse number.

Demonstrated combined laser and magnetic field effects.

Abstract

Deterministic all-optical control of magnetization without an applied magnetic field has been reported for different materials such as ferrimagnetic and ferromagnetic thin films and granular recording media. These findings have challenged the understanding of all-optical helicity-dependent switching of magnetization and opened many potential applications for future magnetic information, memory and storage technologies. Here we demonstrate optical control of an antiferromagnetic layer through the exchange bias interaction using the helicity of a femtosecond pulsed laser on IrMn/[Co/Pt]xN antiferromagnetic/ ferromagnetic heterostructures. We show controlled switching of the sign of the exchange bias field without any applied field, only by changing the helicity of the light, and quantify the influence of the laser fluence and the number of light pulses on the exchange bias control. We also present the combined effect of laser pulses and applied magnetic field. This study opens applications in spintronic devices where the exchange bias phenomenon is routinely used to fix the magnetization orientation of a magnetic layer in one direction.