Magnetic proximity effects in topological insulator heterostructures: Implementation and characterization

In this progress report, we examine recent efforts towards the introduction of magnetic order into topologically nontrivial systems through magnetic proximity effects, with a particular emphasis on the methods of characterizing magnetization induced at the interface. We focus on the challenges associated with comparing magneto-transport measurements with magnetic scattering and spectroscopy techniques, considering the limitations and potential artifacts associated with topological insulator heterostructures. Taking the (Bi, Sb)2(Se, Te) 3 family of three-dimensional topological insulators as an example, we discuss the results associated with a wide range of magnetically ordered reservoirs and highlight the wide discrepancies in reported magnetic proximity effect strengths detected using different characterization techniques. Finally, we discuss the outlook of magnetic proximity effects in topological insulator heterostructures as a route towards a higher-temperature quantum anomalous Hall effect.