Mott Insulators in a Fully-Frustrated Bose Hubbard Model on the Honeycomb Lattice

TL;DR

This study investigates how quantum fluctuations influence a classical spin liquid state in a frustrated honeycomb lattice Bose Hubbard model, revealing a transition to various insulating phases and potential quantum spin liquid states.

Contribution

It introduces a fully-frustrated Bose Hubbard model on the honeycomb lattice and explores the resulting quantum phases using quantum Monte Carlo simulations, highlighting novel Mott insulators.

Findings

Quantum fluctuations induce a superfluid to Mott insulator transition.

Regular interaction modulation leads to valence-bond solid formation.

Irregular interaction modulation results in a featureless, gapped Mott insulator.

Abstract

We examine the effects of quantum fluctuations on a classical spin liquid state in the fully-frustrated honeycomb lattice Bose Hubbard model using quantum Monte Carlo simulations. Frustration is induced explicitly in the model by modulating the sign of the interaction spatially around each lattice hexagon. A superfluid to Mott insulating quantum phase transition can be induced by varying the relative strength of the classical interaction and quantum hopping. In the cases where the interaction has a regular spatial modulation, hopping promotes a phase transition to a symmetry-broken valence-bond solid state. When the interaction is forced to have no regular pattern, the Mott insulating phase is found to be featureless and gapped, making it an interesting candidate state for a quantum spin liquid arising in a Hamiltonian with only nearest-neighbor interactions.