Engineering Topological Surface States of Cr-Doped Bi₂Se₃ Films by Spin Reorientation and Electric Field.

Abstract

The tailoring of topological surface states in topological insulators is essential for device applications and for exploring new topological phase. Here, we propose a practical way to induce the quantum anomalous Hall phase and unusual metal-insulator transitions in Cr-doped Bi₂Se₃ films based on the model Hamiltonian and first-principles calculations. Using the combination of in-plane and plane-normal components of the spin along with external electric fields, we demonstrate that the topological state and band structures of topological insulating films exhibit rich features such as the shift of Dirac cones and the opening of nontrivial band gaps. We also show that the in-plane magnetization leads to significant suppression of inter-TSS scattering in Cr-doped Bi₂Se₃. Our work provides new strategies to obtain the desired electronic structures for the device, complementary to the efforts of an extensive material search.