Interfacing topological insulators and ferrimagnets: Bi₂Te₃ and Fe₃O₄ heterostructures grown by molecular beam epitaxy

Since their initial theoretical prediction, topological insulators have been extensively studied due to the multitude of features stemming from their topological surface states. Many of the recent studies have concentrated on breaking the time reversal symmetry by introducing magnetic order in the system, as this can lead to exotic phenomena such as the quantum anomalous Hall effect. A promising experimental route is to interface topological insulators and magnetic insulators in thin film heterostructures, making use of the magnetic proximity effect. Here we investigate heterostructures grown by molecular beam epitaxy consisting of Bi₂Te₃ and Fe₃O₄ layers. By growing two different types of heterostructures, Fe₃O₄ on Bi₂Te₃ and Bi₂Te₃ on Fe₃O₄, we explore differences in chemical stability, crystalline quality, electronic structure, and transport properties. We find the heterostructure Bi₂Te₃ on Fe₃O₄ to be a more viable approach, with transport signatures in agreement with a gap opening in the topological surface states.

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