Superfluidity and solid orders in two-component Bose gas with dipolar interactions in an optical lattice

TL;DR

This study investigates the phase diagram of a two-component dipolar bosonic system in an optical lattice, revealing stripe and checkerboard solid orders, supersolids, and exotic phases through variational and Monte Carlo methods.

Contribution

It introduces a comprehensive analysis of dipolar interactions in a two-component bosonic system, identifying novel supersolid phases and exotic states not previously characterized.

Findings

Stripe solid order emerges due to dipole-dipole interactions.

Two types of supersolids, checkerboard and stripe, are identified.

An exotic phase exists between stripe solid and checkerboard supersolid.

Abstract

In this paper, we study an extended bosonic t-J model in an optical lattice, which describes two-component hard-core bosons with a nearest-neighbor (NN) pseudo-spin interaction, and also inter- and intra-species dipole-dipole interactions (DDI). In particular, we focus on the case in which two component hard-core bosons have anti-parallel polarized dipoles with each other. The global phase diagram is studied by means of the Gutzwiller variational method and also the quantum Monte-Carlo simulations (QMC). The both calculations show that a stripe solid order, besides a checkerboard one, appears as a result of the DDI. By the QMC, we find that two kinds of supersolid (SS) form, checkerboard SS and stripe SS, and we also verify the existence of some exotic phase between the stripe solid and checkerboard SS. Finally by the QMC, we study the t-J-like model, which was experimentally realized recently by A. de Paz et al. [Phys. Rev. Lett. {\bf 111}, 185305 (2013)].