Coexistence of Canted Antiferromagnetism and Bond-order in $\nu=0$ Graphene

TL;DR

This paper explores the phase diagram of charge-neutral graphene in the quantum Hall regime, revealing a natural coexistence of magnetic and bond orders that explains experimental observations.

Contribution

It demonstrates, through continuum and lattice models, the coexistence of magnetic and bond orders in graphene's phase diagram at charge neutrality.

Findings

Coexistence of magnetic and bond orders in graphene.

The coexistence explains experimental quantum Hall observations.

Both continuum and lattice models support the coexistence phase.

Abstract

Motivated by experimental studies of graphene in the quantum Hall regime, we revisit the phase diagram of a single sheet of graphene at charge neutrality. Because of spin and valley degeneracies, interactions play a crucial role in determining the nature of ground state. We show that, generically, in the regime of interest there is a region of coexistence between magnetic and bond orders in the phase diagram. We demonstrate this result both in continuum and lattice models, and argue that the coexistence phase naturally provides an explanation for unreconciled experimental observations on the quantum Hall effect in graphene.