Non-volatile chirality switching by all-optical magnetization reversal in ferromagnetic Weyl semimetal Co3Sn2S2

Abstract

Weyl semimetals show unique physical properties exemplified by the colossal anomalous Hall effect, arising from exotic quasiparticles called Weyl fermions emerging around the Weyl nodes. Manipulating these topologically protected Weyl nodes is anticipated to play a leading role towards the on-demand control of quantum properties in Weyl semimetals. We demonstrate non-volatile chirality switching in a ferromagnetic Weyl semimetal Co₃Sn₂S₂ via all-optical magnetization reversal. When excited by circularly polarized mid-infrared light pulses, the sign reversal of the anomalous Hall conductivity stemming from the Berry curvature is observed, manifesting the switching of the chirality of the Weyl nodes accompanying with the magnetization reversal. Magneto-optical imaging measurements reveal that the mechanism of the magnetization/chirality switching is attributed to the helicity-dependent deterministic magnetization associated with the magnetic circular dichroism.

Weyl semimetals exhibit a unique feature known as Weyl nodes, which give rise to non-trivial topological features such as an anomalous Hall effect, and there are many efforts to try and control such properties. Here, the authors report light-induced chirality switching in a ferromagnetic Weyl semimetal Co₃Sn₂S₂ using circularly polarized mid-infrared light pulse excitation.