Magnetic-proximity-induced anomalous Hall effect at the EuO/Sb₂Te₃ interface

Time-reversal symmetry breaking of a topological insulator phase generates zero-field edge modes which are the hallmark of the quantum anomalous Hall effect (QAHE) and of possible value for dissipation-free switching or non-reciprocal microwave devices. But present material systems exhibiting the QAHE, such as magnetically doped bismuth telluride and twisted bilayer graphene, are intrinsically unstable, limiting their scalability. A pristine magnetic oxide at the surface of a TI would leave the TI structure intact and stabilize the TI surface, but epitaxy of an oxide on the lower-melting-point chalcogenide presents a particular challenge. Here we utilize pulsed laser deposition to grow (111)-oriented EuO on vacuum cleaved and annealed Sb₂Te₃(0001) surfaces. Under suitable growth conditions, we obtain a pristine interface and surface, as evidenced by x-ray reflectivity and scanning tunneling microscopy, respectively. Despite bulk transport in the thick (2 mm) Sb₂Te₃layers, devices prepared for transport studies show a strong AHE, the necessary precursor to the QAHE. Our demonstration of EuO-Sb₂Te₃epitaxy presents a scalable thin film approach to realize QAHE devices with radically improved chemical stability as compared to competing approaches.