2012/10/31 by Yoshihito Kuno, Y. Kuno, Keisuke Kataoka +3
Mathematics · Physics and Astronomy · #Boson #Cold Atom Physics and Bose-Einstein Condensates #Effective field theory #Hubbard model #Lattice (music) #Mathematics #Path integral formulation #Phase (matter) #Phase diagram #Physics #Physics of Superconductivity and Magnetism #Quantization (signal processing) #Quantum #Quantum mechanics #Quantum, superfluid, helium dynamics #Superconductivity #Theoretical physics #cond-mat.quant-gas #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.87.014518
published as Phys. Rev. B87, 014518 (2013) · 13 pages, 11 figures, Version to be published in Phys. Rev. B
arxiv created 2013/01/23 · openalex publication_date 2013/01/31 · arxiv updated 2015/06/11 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
In this paper, we consider the bosonic t-J model, which describes two-component hard-core bosons with a nearest-neighbor (NN) pseudospin interaction and a NN hopping. To study the phase diagram of this model, we derive effective field theories for low-energy excitations. In order to represent the hard-core nature of bosons, we employ a slave-particle representation. In the path-integral quantization, we first integrate out the radial degrees of freedom of each boson field and obtain the low-energy effective field theory of phase degrees of freedom of each boson field and an easy-plane pseudospin. Coherent condensates of the phases describe, e.g., a ``magnetic order'' of the pseudospin, superfluidity of hard-core bosons, etc. This effective field theory is a kind of extended quantum XY model, and its phase diagram can be investigated precisely by means of the Monte Carlo simulations. We then apply a kind of Hubbard-Stratonovich transformation to the quantum XY model and obtain the second version of the effective field theory, which is composed of fields describing the pseudospin degrees of freedom and boson fields of the original two-component hard-core bosons. As an application of the effective-field theory approach, we consider the bosonic t-J model on the square lattice and also on the triangular lattice, and compare the obtained phase diagrams with the results of the numerical studies. We also study low-energy excitations rather in detail in the effective field theory. Finally, we consider the bosonic t-J model on a stacked triangular lattice and obtain its phase diagram. We compare the obtained phase diagram with that of the effective field theory to find close resemblance.