Quantum anomalous Hall effect in Cr2Ge2Te6/Bi2Se3/Cr2Ge2Te6heterostructures.

ABSTRACT

Currently, quantum anomalous Hall (QAH) effect can only be observed at very low temperatures, which severely hinders its utilization from spintronics to quantum computation. Finding or predicting new systems supporting QAH effect at high temperatures remains essential and challenging. This work presents first-principles studies on the proximity effect between Bi2Se3slabs and Cr2Ge2Te6(CGT) layers, reporting that Chern insulators are available in CGT/Bi2Se3/CGT heterostructures. If the sandwiched Bi2Se3slab is 4 quintuple layers (QLs) or thicker, the Chern insulating state is robust against the interfacial stacking manner. If the Bi2Se3slab is only 2 or 3 QLs, the CrBi- and CrH-aligned heterostructures are also Chern insulators, while the CrSe-aligned ones are trivial. The Chern insulators support the Hall conductivityσxy=e2/hand have energy gaps ranging from 3 to 20 meV, implying QAH effect at higher temperatures. An effective model Hamiltonian is introduced to understand the topological phase of the heterostructures.