Interfacial chirality-induced magnetic-field-free switching with high energy efficiency in all-vdW heterostructures

Chirality, a central concept across many scientific disciplines, continues to inspire the discovery of novel physical phenomena. In condensed matter physics, structural chirality—defined by the absence of mirror plane symmetries—has primarily been explored in bulk materials. However, new chiral phenomena can emerge uniquely at the interface, distinct from their bulk counterparts, when a chiral material forms a heterostructure. Here, we demonstrate that all van-der-Waals (vdW) heterostructure composed of the chiral Co1/3TaS2 and the achiral vdW ferromagnet Fe3GeTe2 exhibits two distinct and unconventional spin-orbit torques originating from the interfacial chirality. These torques enable magnetic-field-free switching of perpendicular magnetization with ultralow current density ~ \,10⁶\,A/cm² and minimal power dissipation < 10¹⁵\,W/m³. Moreover, by replacing Fe3GeTe2 with a similar vdW ferromagnet, Fe3GaTe2, but of higher Curie temperature, we achieved the magnetic-field-free switching at room temperature in the Fe3GaTe2/Co1/3TaS2 vdW heterostructure. Our findings establish interfacial chirality as a powerful new handle for spintronic control, opening a new pathway to explore chirality-induced phenomena beyond the bulk symmetry constraints – and paving the way toward highly efficient, low-power spintronic devices based on all-vdW heterostructures. Deterministic spin-orbit torque induced magnetization switching either requires an additional biasing magnetic field or reduced symmetry in the spin-orbit torque source. Here, Zhang, Cheon, and coauthors show how interfacial chirality resulting from the inclusion of the chiral crystal Co1/3TaS2 allows for the field free switching of a van der Waals ferromagnet.