Large Fieldlike Spin-Orbit Torque and Magnetization Manipulation in a Fully Epitaxial van der Waals Two-Dimensional-Ferromagnet/Topological-Insulator Heterostructure Grown by Molecular-Beam Epitaxy

Abstract

With the development of technologies taking advantage of emerging quantum phenomena under extreme conditions of dimensionality and temperature, the search for alternative materials and heterostructure engineering has opened up on several fronts. Here, we report the magnetotransport properties of topological-insulator/two-dimensional-ferromagnet (TI/2D-FM) heterostructures composed of ${\mathrm{Cr}}_{1+\ensuremath{\delta}}{\mathrm{Te}}_{2}/{\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ stacks grown by molecular-beam epitaxy. The electrical transport measurements reveal high levels of fieldlike effective torques, up to 115 mT at a current density of ${10}^{7}\phantom{\rule{0.25em}{0ex}}\mathrm{A}/{\mathrm{cm}}^{2}$; the occurrence of interfacial magnetoresistance effects, such as the anisotropic interfacial magnetoresistance; and anomalies in the anomalous Hall effect. Furthermore, we report on complementary characterization with scanning tunneling microscopy, angle-resolved photoemission spectroscopy, and superconducting quantum interference device measurements. Finally, magnetization reversal induced by current pulses is also reported. The reported results make the relevance of the TI/2D-FM interface evident and indicate the preservation of polarized surface states at the interface.