Surfaces of axion insulators
Open Access
- 12 December 2018
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 98 (24), 245117
- https://doi.org/10.1103/PhysRevB.98.245117
Abstract
Axion insulators are magnetic topological insulators in which the nontrivial Z(2) index is protected by inversion symmetry instead of time-reversal symmetry. The naturally gapped surfaces of axion insulators give rise to a half-quantized surface anomalous Hall conductivity (AHC), but the sign of the surface AHC cannot be determined from topological arguments. In this paper, we consider topological phenomena at the surface of an axion insulator. To be explicit, we construct a minimal tight-binding model on the pyrochlore lattice and investigate the all-in-all-out (AIAO) and ferromagnetic (FM) spin configurations. We also implement a recently proposed approach for calculating the surface AHC directly, which allows us to explore how the interplay between surface termination and magnetic ordering determines the sign of the half-quantized surface AHC. In the case of AIAO ordering, we show that it is possible to construct a topological state with no protected metallic states on boundaries of any dimension (surfaces, hinges, or corners), although chiral hinge modes do occur for many surface configurations. In the FM case, rotation of the magnetization by an external field offers promising means of control of chiral hinge modes, which can also appear on surface steps or where bulk domain walls emerge at the surface.Keywords
Funding Information
- National Science Foundation (DMR-1408838)
This publication has 48 references indexed in Scilit:
- Realization of the Axion Insulator State in Quantum Anomalous Hall Sandwich HeterostructuresPhysical Review Letters, 2018
- Tailoring tricolor structure of magnetic topological insulator for robust axion insulatorScience Advances, 2017
- Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulatorScience, 2016
- Direct evidence for the all-in/all-out magnetic structure in the pyrochlore iridates from muon spin relaxationPhysical Review B, 2014
- Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological InsulatorScience, 2013
- Determination of long-range all-in-all-out ordering of Ir${}^{4+}$ moments in a pyrochlore iridate Eu${}_{2}$Ir${}_{2}$O${}_{7}$ by resonant x-ray diffractionPhysical Review B, 2013
- Emergence of Magnetic Long-range Order in Frustrated Pyrochlore Nd2Ir2O7with Metal–Insulator TransitionJournal of the Physics Society Japan, 2012
- Erratum: Magnetoelectric Polarizability and Axion Electrodynamics in Crystalline Insulators [Phys. Rev. Lett.102, 146805 (2009)]Physical Review Letters, 2009
- Magnetoelectric Polarizability and Axion Electrodynamics in Crystalline InsulatorsPhysical Review Letters, 2009
- Topological field theory of time-reversal invariant insulatorsPhysical Review B, 2008