Majorana-Hubbard model on the honeycomb lattice

TL;DR

This paper investigates a Majorana-Hubbard model on the honeycomb lattice, revealing topological phases and a potential spin liquid ground state through theoretical and numerical methods.

Contribution

It introduces the phase diagram of the model, showing how weak interactions induce topological phases and proposing a new frustrated spin model at strong coupling.

Findings

Two topologically nontrivial phases identified at weak coupling

Weak interactions break symmetries and induce topological order

Strong coupling suggests a highly entangled spin liquid ground state

Abstract

Phase diagram of a Hubbard model for Majorana fermions on the honeycomb lattice is explored using a combination of field theory, renormalization group and mean-field arguments, as well as exact numerical diagonalization. Unlike the previously studied versions of the model we find that even weak interactions break symmetries and lead to interesting topological phases. We establish two topologically nontrivial phases at weak coupling, one gapped with chiral edge modes, and the other gapless with anti-chiral edge modes. At strong coupling a mapping onto a novel frustrated spin-${1\over 2}$ model suggests a highly entangled spin liquid ground state.