Topological phases in Iridium oxide superlattices: quantized anomalous charge or valley Hall insulators

TL;DR

This paper explores various topological phases in Iridium oxide superlattices, revealing potential for quantized anomalous Hall effects, valley Hall insulators, and topological insulators under different conditions, driven by strong spin-orbit coupling and lattice symmetries.

Contribution

It identifies new topological phases in Ir oxide superlattices, including magnetic, valley, and crystalline insulators, and discusses how strain and magnetic fields can induce these states.

Findings

Ir oxide bilayers exhibit quantized anomalous Hall effects.

Different stacking configurations lead to valley Hall and crystalline topological insulators.

Strain and magnetic fields can induce topological insulating phases.

Abstract

We study topological phases in Iridium (Ir) oxide superlattices of orthorhombic perovskite-type grown along the [001] crystallographic axis. Due to strong spin-orbit coupling of Ir 5d-orbitals and electronic correlation effects, Ir oxide bilayer superlattices display topological magnetic insulators exhibiting quantized anomalous Hall effects. Depending on stacking of two layers, we also found a valley Hall insulator with counter-propagating edge currents from two different valleys and a topological crystalline insulator with edge states protected by the crystal lattice symmetry. In a single layer Ir oxide superlattice, a topological insulator can be achieved, when a strain field is applied to break the symmetry of a glide plane protecting the Dirac points. In the presence of a magnetic ordering or in-plane magnetic field, it turns into a topological magnetic insulator. We discuss essential ingredients for these topological phases and experimental signatures to test our theoretical proposals.