Axion insulator states in a topological insulator proximitized to magnetic insulators: A tight-binding characterization

Abstract

Recent discovery of axion states in materials such as antiferromagnetic topological insulators boosted investigations of magnetoelectric response in topological insulators and their promise towards dissipationless topological electronics. In this paper, we develop a tight-binding methodology to explore the emergence of axion states in Bi2Se3 in proximity to magnetic insulators on top and bottom surfaces. The topological protection of the surface states is lifted by a time-reversal-breaking perturbation due to proximity of a magnetic insulator and a gap is opened on the surfaces, giving rise to half-quantized Hall conductance and zero Hall plateau -evidencing an axion insulator state. We developed a real-space tight-binding Hamiltonian for Bi2Se3 using first-principles data. Transport properties of the system were obtained within the Landauer-Büttiker formalism, and discuss the creation of axion states through Hall conductance and zero Hall plateau at the surfaces, as a function of proximitized magnetization and corresponding potentials at the surfaces, as well as the thickness of the topological insulator.

Polarization conversion and lateral shifts in multilayered structure with finitely-gapped topological surface states

“…Magnetic doping is an effective way to offer magnetic exchange interaction to TI, where epitaxial deposition of magnetic atoms is performed onto the TI surface [15][16][17]. The magnetic proximity refers to topological-magnetic insulator heterostructures where TI is interfaced with magnetic insulator [18][19][20][21]. In these recent advances, finite surface energy gaps that can be opened have been measured and investigated.…”