Interplay between edge states and charge density wave order in the Falicov-Kimball model on a Haldane ribbon

TL;DR

This paper investigates how edge states influence the phase diagram of the Falicov-Kimball model on a Haldane lattice, revealing edge-induced phases and the interplay with charge density waves in a ribbon geometry.

Contribution

It introduces a detailed analysis of edge effects and interference in a Haldane ribbon, identifying new edge-induced phases and their relation to charge density waves.

Findings

Edge states induce a topologically trivial bulk insulator with metallic edges.

Charge density wave phases are affected by local doping caused by edge states.

Two new gapless phases are identified, dependent on ribbon width.

Abstract

To determine the impact of including edge states on the phase diagram of a spinless Falicov-Kimball model (FKM) on the Haldane lattice, a study of a corresponding ribbon geometry with zigzag edges is conducted. By varying the ribbon widths, the distinction between the effects connected to the mere presence of the edges and those originating from interference between the edge states is established. The local doping caused by the former is shown to give rise to a topologically trivial bulk insulator with metallic edge states. Additionally, it gives rise to a charge density wave (CDW) phase with mixed character of the subbands in various parts of the phase diagram. The local doping on the CDW instability is also addressed. Two additional gapless phases are found, caused by the edges but with stability regions depending on the width of the ribbon.