Passivation of Bi2Te3 Topological Insulator by Transferred CVD‐Graphene: Toward Intermixing‐Free Interfaces

The investigation, and ultimate application, of topological insulators, typically involve exposure to ambient conditions or their integration with metals, which lead to surface oxidation or material intermixing. X‐ray photoelectron spectroscopy (XPS) measurements that demonstrate passivated and intermixing‐free interfaces in the topological insulator Bi2Te3 by means of dry‐transferred CVD graphene are reported. After air exposure, no traces of Bi2Te3 oxidation are found. Furthermore, it is demonstrated that graphene acts as a very efficient metal and chalcogen diffusion barrier in Bi2Te3/graphene/permalloy (Py) heterostructures, which are relevant for spintronics. Such results are in stark contrast with the significant surface degradation observed in bare Bi2Te3 under ambient conditions and the deep BiTe bonding disruption that occurs in Bi2Te3/Py heterostructures. These findings provide a new approach to control and engineer topological insulator interfaces for spintronic applications and a new platform to investigate the combined use of graphene and topological insulator Dirac states.