Large anomalous Hall effect in ferromagnetic insulator-topological insulator heterostructures

We demonstrate the van der Waals epitaxy of the topological insulator compound Bi₂Te₃ on the ferromagnetic insulator Cr₂Ge₂Te₆. The layers are oriented with (001)Bi₂Te₃||(001)Cr₂Ge₂Te₆ and (110)Bi₂Te₃||(100)Cr₂Ge₂Te₆. Cross-sectional transmission electron microscopy indicates the formation of a sharp interface. At low temperatures, bilayers consisting of Bi₂Te₃ on Cr₂Ge₂Te₆ exhibit a large anomalous Hall effect (AHE). Tilted field studies of the AHE indicate that the easy axis lies along the c-axis of the heterostructure, consistent with magnetization measurements in bulk Cr₂Ge₂Te₆. The 61 K Curie temperature of Cr₂Ge₂Te₆ and the use of near-stoichiometric materials may lead to the development of spintronic devices based on the AHE.