Optically induced thermal demagnetization and switching of antiferromagnetic domains in NiO and CoO thin films

TL;DR

This paper demonstrates all-optical control of antiferromagnetic domains in NiO and CoO thin films using laser-induced thermal effects, enabling reversible switching without electric currents.

Contribution

It introduces a method for ultrafast optical manipulation of antiferromagnetic domains through thermal gradients, with a simple analytical model explaining the domain wall motion.

Findings

Single laser pulses can thermally demagnetize antiferromagnets.

Controlled domain wall motion and partial switching are achieved by beam sweeping.

Reversible toggling of domains is possible by reversing thermal gradients.

Abstract

We demonstrate all-optical manipulation of magnetic domains in NiO/Pt and CoO/Pt thin films with insulating antiferromagnetic layers. Using magneto-optical birefringence imaging, we show that even a single laser pulse can thermally demagnetize the antiferromagnet, leading to a random redistribution of domains. By sweeping the laser beam, controlled domain wall motion is induced, enabling partial switching of the antiferromagnetic order. The behavior is captured by an analytical model in which temperature gradients generated by the moving beam exert a thermal pressure on domain walls in the form of a ponderomotive force. Importantly, the 90$^{\circ}$ domains can be reversibly toggled solely by reversing the direction of the thermal gradient, demonstrating all-optical switching without the need for electric currents. These findings establish a route toward ultrafast optical manipulation of fully compensated antiferromagnets, with potential impact on non-volatile memory technologies and antiferromagnetic spintronics.