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

Guillet, Thomas; Galceran, Regina; Sierra, Juan F; Belarre, Francisco J; Ballesteros, Belén; Costache, Marius V; Dosenovic, Djordje; Okuno, Hanako et al. · Nano Lett · 2024

basic_science · Level V

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Abstract

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)<sub>2</sub>Te<sub>3</sub> with 2D FM Fe<sub>3</sub>GeTe<sub>2</sub> (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 <i>J</i><sub>c</sub> ∼ 10<sup>10</sup> A/m<sup>2</sup>, with minimal device-to-device variations compared to previous investigations involving traditional FMs.