Facilitating field-free perpendicular magnetization switching with a Berry curvature dipole in a Weyl semimetal

TL;DR

This paper demonstrates that a Berry curvature dipole in WTe2 enables field-free perpendicular magnetization switching in heterostructures, advancing spintronic memory technology through combined orbital and spin-orbit torques.

Contribution

It reveals how orbital and spin-orbit torques synergize via Berry curvature dipole to achieve controllable, field-free magnetization switching in WTe2/Fe3GeTe2 heterostructures, with potential memory device applications.

Findings

Orbital Edelstein effect induces out-of-plane magnetization.

Controlled field-free switching of Fe3GeTe2 layer.

Demonstration of independent manipulation of torques.

Abstract

We report the synergy between orbital and spin-orbit torques in WTe2/Fe3GeTe2 heterostructures characterized by a Berry curvature dipole. By applying a current along the a axis in WTe2, we detect an out-of-plane magnetization in the system, which we attribute to nonequilibrium orbital magnetization linked to the Berry curvature dipole based on first-principles calculations, manifesting as the orbital Edelstein effect. This effect generates orbital torques that enable field-free perpendicular magnetization switching. Furthermore, by applying a relatively small current along the a axis and a pulsed current along the b axis in WTe2, we demonstrate controllable field-free magnetization switching of the adjacent Fe3GeTe2 layer, independently manipulating the orbital and spin-orbit torques. Our findings not only enhance the understanding of the collaborative dynamics between these torques but also suggest potential applications in magnetoresistive random-access memory.