Abstract

We study finite-temperature phase structure of two-component hard-core bosons in a cubic optical lattice. This system is an effective system for the bosonic Hubbard model with strong on-site repulsions and is called bosonic t-J model, which can be regarded as a bosonic counterpart of the t-J model for the strongly-correlated electron systems like the high-temperature superconducting materials. We study the model by means of path-integral methods and Monte-Carlo simulations: We found that this system has very rich phase structure including checkerboard-type "insulating" state, superfluid, phase-separated state, inhomogeneous cloudlet state, etc. This result gives important insight into mechanism of the high-temperature superconductivity of cuprate.