Supersolid hardcore bosons on the triangular lattice

TL;DR

This paper maps the phase diagram of hardcore bosons on a triangular lattice, revealing stable supersolid phases at intermediate densities and characterizing the nature of phase transitions.

Contribution

It provides the first detailed analysis of the stability of supersolid phases in this model on a triangular lattice, including at half filling.

Findings

Supersolid phase is unstable for densities below 1/3 and above 2/3.

First-order transition occurs between solid and superfluid phases outside the supersolid region.

Extended supersolid phase exists at intermediate densities, including at half filling.

Abstract

We determine the phase diagram of hardcore bosons on a triangular lattice with nearest neighbor repulsion, paying special attention to the stability of the supersolid phase. Similar to the same model on a square lattice we find that for densities $\rho<1/3$ or $\rho>2/3$ a supersolid phase is unstable and the transition between a commensurate solid and the superfluid is of first order. At intermediate fillings $1/3 < \rho < 2/3$ we find an extended supersolid phase even at half filling $\rho=1/2$.