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.