2D ferromagnet/topological insulator van der Waals heterostructures grown by molecular beam epitaxy*

Near-room-temperature gate tunable 2D vdW ferromagnets (FM) such as Fe₃GeTe₂ (FGT) and CrTe₂ [1,2] have ignited interest for the study of the structural and magnetic properties of epitaxial FM/TI heterostructures [3] with the aim to obtain efficient charge-to-spin conversion [4] and spin-orbit torques for spintronics. In this work we present MBE-grown Cr_xTe_y and FGT on several substrates. The CrTe₂ phase is confirmed by RHEED, STM, Raman and ARPES, supported by DFT calculations of the electronic band structure. Probed by SQUID magnetometry, both CrTe₂ and FGT are ferromagnetic and show perpendicular magnetic anisotropy. 5 ML FGT show a large anomalous hall effect (AHE) which persists up to 309K. Bi₂Te₃/FGT heterostructure shows partial but also consistent magnetization reversal induced by pulsed current through the Bi₂Te₃. The associated σ_xy^AHE=24 [Ωcm]^-1 of CrTe₂ is compatible with the contribution from the Berry curvature predicted by our theoretical calculations. Bi₂Te₃/CrTe₂ heterostructure is probed by second harmonic technique revealing large damping and field-like torques.

1. Y. Deng et al., Nature 563, 94 (2018)

2. X. Zhang et al., Nat. Commun. 12, 2492 (2021)

3. H. Wang et al., ACS Nano 14, 10045 (2020)

4. Mogi et al., Nat. Commun. 12, 1404 (2021)