Mott Transition and Spin Structures of Spin-1 Bosons in Two-Dimensional Optical Lattice at Unit Filling

Abstract

We study the ground state properties of spin-1 bosons in a two-dimensional optical lattice, by applying a variational Monte Carlo method to the S=1 Bose-Hubbard model on a square lattice at unit filling. A doublon-holon binding factor introduced in the trial state provides a noticeable improvement in the variational energy over the conventional Gutzwiller wave function and allows us to deal effectively with the inter-site correlations of particle densities and spins. We systematically show how spin-dependent interactions modify the superfluid-Mott insulator transitions in the S=1 Bose-Hubbard model due to the interplay between the density and spin fluctuations of bosons. Furthermore, regarding the magnetic phases in the Mott region, the calculated spin structure factor elucidates the emergence of nematic and ferromagnetic spin orders for antiferromagnetic ($U_2>0$) and ferromagnetic ($U_2<0$) couplings, respectively.

arXiv comment5 pages, 5 figures, to appear in Journal of the Physical Society of Japan

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Cited by in corpus (11)

• Ultracold bosons with short-range interaction in regular optical lattices
• Interacting spin-1 bosons in a two-dimensional optical lattice
• Anderson tower of states and nematic order of spin-1 bosonic atoms on a 2D lattice
• Strong-coupling expansion for the spin-1 Bose-Hubbard model
• Mott lobes of the $S=1$ Bose-Hubbard model with three-body interactions
• Dynamical instability in the S=1 Bose-Hubbard model
• Phase Diagrams of Antiferromagnetic Spin-1 Bosons on Square Optical Lattice with the Quadratic Zeeman Effect
• Spin-1 Quantum Walks
• Spin-1 Bose-Hubbard model with two- and three-body interactions
• Strong-coupling study of spin-1 bosons in square and triangular optical lattice
• Spinor bosons in optical superlattices: a numerical study