Models of Strong Interaction in Flat-Band Graphene Nanoribbons: Magnetic Quantum Crystals

TL;DR

This paper develops a model for interacting electrons in flat-band graphene nanoribbons, showing that at low densities, these systems can support ferromagnetic quantum crystal ground states due to flat-band effects.

Contribution

It introduces a flat-band projection protocol and demonstrates the potential for ferromagnetic quantum crystals in zig-zag graphene nanoribbons.

Findings

Flat bands can delocalize single-particle states.

Interaction-only tight-binding models are derived.

Ferromagnetic quantum crystal ground states are supported at low densities.

Abstract

Graphene based nanostructures exhibit flat electronic energy bands in their single-particle spectrum. We consider interacting electrons in flat bands of zig-zag nanoribbons. We present a protocol for flat-band projection that yields interaction-only tight-binding models. We argue that, at low densities, flat bands can delocalize single-particle basis states to support ferromagnetic quantum crystal ground states.