Publications (3)0 Total impact
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ABSTRACT: In the present paper, we study finite-temperature phase structure of
two-component hard-core bosons in a cubic optical lattice. The system that we
study in the present paper is an effective model for the Bose-Hubbard model
with strong on-site repulsions and is called bosonic t-J model. This model is 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 a very rich phase structure including checkerboard-type
"insulating" state, superfluid, phase-separated state, inhomogeneous cloudlet
state, etc. We are also interested in the possible supersolid phase with both
the checkerboard order and superfluidity and found that additional
nearest-neighbor inter-species attractive force induces the supersolid state.
In the supersolid state, paired superfluid appears in addition to the
superfluid of single atom. This result gives important insight into mechanism
of the high-temperature superconductivity of the cuprate.
12/2011;
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ABSTRACT: We study the three-dimensional bosonic t-J model, i.e., the t-J model of "bosonic electrons" at finite temperatures. This model describes a system of cold bosonic atoms with two species in an optical lattice. The model is derived from the Hubbard model for very large on-site repulsive interaction between bosons of same species (hard-core nature) and also strong correlations between different species. The operator B_{x\sigma} for an atom at the site x with a two-component (pseudo-) spin \sigma (=1,2) is treated as a hard-core boson operator, and represented by a composite of two slave particles; a spinon described by a CP^1 field (Schwinger boson) z_{x\sigma} and a holon described by a hard-core-boson field \phi_x as B_{x\sigma}=\phi^\dag_x z_{x\sigma}. \phi_x is then expressed by a pseudo-spin, which is, in turn, represented by another CP^1 (pseudo) spinon w_{x\eta} as \phi_x = w_{x2}^\dag w_{x1}. We then have a double-CP^1 representation of the model by z_{x\sigma} and w_{x\eta}. By means of Monte Carlo simulations of this bosonic t-J model, we study its phase structure and the possible phenomena like appearance of antiferromagnetic long-range order, Bose-Einstein condensation, phase separation, etc. They should be compared with the possible experimental results of a recently studied boson-boson mixture like ^87Rb and ^41K in an optical lattice. Comment: 13 pages, 17 figures
05/2010;
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ABSTRACT: We study the three-dimensional bosonic t-J model, that is, the t-J model of “bosonic electrons” at finite temperatures. This model describes a system of an isotropic antiferromagnet with doped bosonic holes and is closely related to systems of two-component bosons in an optical lattice. The bosonic “electron” operator Bxσ at the site x with a two-component spin σ(=1,2) is treated as a hard-core boson operator and represented by a composite of two slave particles: a spinon described by a Schwinger boson (CP1 boson) zxσ and a holon described by a hard-core-boson field ϕx as Bxσ=ϕx†zxσ. By means of Monte Carlo simulations of this bosonic t-J model, we study its phase structure and the possible phenomena like appearance of antiferromagnetic long-range order, Bose-Einstein condensation, phase separation, etc. Obtained results show that the bosonic t-J model has a phase diagram that suggests some interesting implications for high-temperature superconducting materials.
Phys. Rev. B. 83(23).
