Topological hall effect in Bi/Cr₂Te₃ heterostructure thin films

Abstract

The topological Hall effect (THE) due to the spatially varying magnetizations appears as humps and dips near the coercive field in the Hall resistance curves. It is possible that magnetic skyrmions might be applied to next-generation data storage devices. Previous calculations predicted that the combination of Cr2Te3 thin film with strong perpendicular anisotropy (PMA) and Bi with strong spin-orbit coupling (SOC) could induce Dzyaloshinskii-Moriya interaction (DMI) and magnetic skyrmions. THE has been observed in Cr2Te3 thin films with Bi bilayer nanosheets intercalated. However, the distribution of inserted Bi nanosheets was random, therefore, locating and studying the interface between Bi and Cr2Te3 layers is difficult. The growth scheme of Bi on the Cr2Te3 surface is still blank. In this work, Bi/Cr2Te3 heterostructure thin films were fabricated by molecular beam epitaxy (MBE). The Bi (1 1 0) surface was grown on the Cr2Te3 (0 0 0 1) layer in islands from cross-sectional and plane-view scanning transmission electron microscopy (STEM) observation. THE signals were observed in the Bi/Cr2Te3 heterostructure thin films below 130 K. The two-component anomalous Hall effect (AHE) that might induce similar hump and dip signals near the coercive field was excluded by the minor loop method.