arXiv:1311.1604 · Physical Review A
Two-species hard-core bosons on the triangular lattice: A quantum Monte Carlo study
Jian-Ping Lv, Qing‐Hu Chen, Youjin Deng
Abstract
Using worm-type quantum Monte Carlo simulations, we investigate bosonic mixtures on a triangular lattice of two species of bosons, which interact via nearest-neighbor intraspecies ($V$) and on-site interspecies ($U$) repulsions. For the case of symmetric hopping amplitude (${t}_{A}/V={t}_{B}/V$) and $U/V=1$, we determine a rich ground-state phase diagram that contains double-solid, double-superfluid, supersolid (SS), solid-superfluid (solid-SF), and counterflow supersolid (CSS) states. The SS, solid-SF, and CSS states exhibit spontaneous symmetry breaking among the three sublattices of the triangular lattice and between the two species, which leads to a nonzero crystalline density wave order in each species. We, furthermore, show that the CSS and the SS states are present for ${t}_{A}/V\ensuremath{\ne}{t}_{B}/V$, and the latter even survives up to the ${t}_{A}/V\ensuremath{\rightarrow}\ensuremath{\infty}$ or ${t}_{B}/V\ensuremath{\rightarrow}\ensuremath{\infty}$ limit. The effects induced by the variation of $U/V$ and by the imbalance of particle numbers of the two species are also explored.