Realizing Haldane Model in Fe-based Honeycomb Ferromagnetic Insulators

TL;DR

This paper proposes that certain Fe-based honeycomb ferromagnetic insulators can realize the topological Haldane model, providing a new pathway to observe quantum anomalous Hall effects in solid-state materials.

Contribution

It introduces Fe-based honeycomb ferromagnetic insulators as candidate materials for realizing the Haldane model in condensed matter systems.

Findings

Fe-based honeycomb ferromagnetic insulators possess Chern bands described by the Haldane model.

Potential methods for detecting the quantum anomalous Hall effect in these materials.

Identification of specific compounds (AFe2(PO4)2) as promising candidates.

Abstract

The topological Haldane model (THM) on a honeycomb lattice is a prototype of systems hosting topological phases of matter without external fields. It is the simplest model exhibiting the quantum Hall effect without Landau levels, which motivated theoretical and experimental explorations of topological insulators and superconductors. Despite its simplicity, its realization in condensed matter systems has been elusive due to a seemingly difficult condition of spinless fermions with sublattice-dependent magnetic flux terms. While there have been theoretical proposals including elaborate atomic-scale engineering, identifying candidate THM materials has not been successful, and the first experimental realization was recently made in ultracold atoms. Here we suggest that a series of Fe-based honeycomb ferromagnetic insulators, AFe2(PO4)2 (A=Ba,Cs,K,La) possess Chern bands described by the THM. How to detect the quantum anomalous Hall effect is also discussed.