Chern insulators from heavy atoms on magnetic substrates

TL;DR

This paper proposes a method to find Chern insulators by depositing heavy atoms on magnetic insulators and uses first-principles calculations to identify promising candidates with sizable energy gaps.

Contribution

It introduces a new search strategy for Chern insulators using surface deposition and verifies it through first-principles calculations on various magnetic substrates.

Findings

Identified several candidate Chern insulators with gaps up to 140 meV.

Developed a criterion based on the Fermi level in a global gap for Chern insulator realization.

Validated the search strategy with computational analysis of multiple systems.

Abstract

We propose searching for Chern insulators by depositing atomic layers of elements with large spin-orbit coupling (e.g., Bi) on the surface of a magnetic insulator. We argue that such systems will typically have isolated surface bands with non-zero Chern numbers. If these overlap in energy, a metallic surface with large anomalous Hall conductivity (AHC) will result; if not, a Chern-insulator state will typically occur. Thus, our search strategy reduces to looking for examples having the Fermi level in a global gap extending across the entire Brillouin zone. We verify this search strategy and identify several candidate systems by using first-principles calculations to compute the Chern number and AHC of a large number of such systems on MnTe, MnSe, and EuS surfaces. Our search reveals several promising Chern insulators with gaps of up to 140\,meV.