Proximity-induced anomalous Hall effect and carrier-type-dependent weak localization effect in (Bi, Sb)₂Te₃ thin films due to Cr₂O₃ interfacial layers

The quantum anomalous Hall effect (QAHE), the quantized version of the anomalous Hall effect (AHE), is an emergent physical phenomenon where electrons can flow along the edges of the sample without dissipation in the absence of a magnetic field, exhibiting quantized Hall resistance. Till now, QAHE was mainly observed in magnetic topological insulators (MTIs) under extreme conditions, including low temperatures and external electric fields. Since intrinsic MTIs like MnBi₂Te₄ are rare, most MTIs are realized through (magnetic) doping into topological insulators, such as Cr- or V-doped (Bi, Sb)₂Te₃. However, magnetic proximity coupling might be another effective approach to realize QAHE, providing more homogeneous interaction. The AHE-induced proximity effect has been discovered in multiple magnetic insulator/topological insulator heterostructures.

Here, we demonstrate that by utilizing the antiferromagnetic insulator Cr₂O₃ as a buffer on a sapphire substrate and chromium oxide as a capping layer. proximity-induced AHE was discovered in epitaxial thin (Bi, Sb)₂Te₃ film using molecular beam epitaxy (MBE). We also found competition between weak localization and weak antilocalization in these samples, depending on the carrier type.