Magnetized topological insulator multilayers

Abstract

We discuss the magnetic and topological properties of bulk crystals and quasi–two-dimensional (quasi-2D) thin films formed by stacking intrinsic magnetized topological insulator (for example, Mn (SbxBi1−x)2X4with X = Se,Te) septuple layers and topological insulator quintuple layers in arbitrary order. Our analysis makes use of a simplified model that retains only Dirac cone degrees of freedom on both surfaces of each septuple or quintuple layer. We demonstrate the model’s applicability and estimate its parameters by comparing with ab initio density-functional theory (DFT) calculations. We then employ the coupled Dirac cone model to provide an explanation for the dependence of thin-film properties, particularly the presence or absence of the quantum anomalous Hall effect, on film thickness, magnetic configuration, and stacking arrangement, and to comment on the design of Weyl superlattices.