Spin-Orbit Torques and Magnetization Switching in (Bi,Sb) 2 Te 3 /Fe 3 GeTe 2 Heterostructures Grown by Molecular Beam Epitaxy.

Topological insulators (TIs) hold promise for manipulating the magnetization of a ferromagnet (FM) through the spin-orbit torque (SOT) mechanism. However, integrating TIs with conventional FMs often leads to significant device-to-device variations and a broad distribution of SOT magnitudes. In this work, we present a scalable approach to grow a full van der Waals FM/TI heterostructure by molecular beam epitaxy, combining the charge-compensated TI (Bi,Sb) ₂ Te ₃ with 2D FM Fe ₃ GeTe ₂ (FGT). Harmonic magnetotransport measurements reveal that the SOT efficiency exhibits a non-monotonic temperature dependence and experiences a substantial enhancement with a reduction of the FGT thickness to 2 monolayers. Our study further demonstrates that the magnetization of ultrathin FGT films can be switched with a current density of J _c ∼ 10 ¹⁰ A/m ² , with minimal device-to-device variations compared to previous investigations involving traditional FMs.