Supersolid phase transitions for hardcore bosons on a triangular lattice

TL;DR

This paper analyzes the supersolid phase transition in hardcore bosons on a triangular lattice, providing an analytical understanding of its origin and predicting phase boundaries with high accuracy, supported by numerical simulations.

Contribution

It introduces an effective quasiparticle model to explain the supersolid phase and accurately predicts phase transition lines for both frustrated and non-frustrated hopping.

Findings

Analytical model matches Quantum Monte Carlo results for positive hopping.

Identifies the supersolid to superfluid transition as first order.

Predicts phase boundaries for both positive and negative hopping parameters.

Abstract

Hard-core bosons on a triangular lattice with nearest neighbor repulsion are a prototypical example of a system with supersolid behavior on a lattice. We show that in this model the physical origin of the supersolid phase can be understood quantitatively and analytically by constructing quasiparticle excitations of defects that are moving on an ordered background. The location of the solid to supersolid phase transition line is predicted from the effective model for both positive and negative (frustrated) hopping parameters. For positive hopping parameters the calculations agree very accurately with numerical Quantum Monte Carlo simulations. The numerical results indicate that the supersolid to superfluid transition is first order.