Quarter-Filled Honeycomb Lattice with a Quantized Hall Conductance

TL;DR

This paper investigates a two-dimensional honeycomb lattice model with strong spin-orbit coupling at quarter filling, demonstrating that a quantized Hall conductance can emerge due to Zeeman fields and spontaneous ferromagnetism, independent of topological insulator conditions.

Contribution

It introduces a generic model showing quantized Hall conductance at quarter filling without requiring the lattice to be a topological insulator, emphasizing the role of Zeeman fields and interactions.

Findings

Quantized Hall conductance appears at quarter filling with strong Zeeman fields.

Spontaneous ferromagnetism can induce a quantized anomalous Hall effect.

The model does not require the lattice to be a topological insulator.

Abstract

We study a generic two-dimensional hopping model on a honeycomb lattice with strong spin-orbit coupling, without the requirement that the half-filled lattice be a Topological Insulator. For quarter-(or three-quarter) filling, we show that a state with a quantized Hall conductance generically arises in the presence of a Zeeman field of sufficient strength. We discuss the influence of Hubbard interactions and argue that spontaneous ferromagnetism (which breaks time-reversal) will occur, leading to a quantized anomalous Hall effect.