Superfluid-Mott insulator transition of spin-1 bosons in an optical lattice
- Department of Physics, Waseda University, 3-4-1 Okubo, Tokyo 169-8555 (Japan)
- Department of Physics, Waseda University and Physics of Self-Organization Systems, 21st Century COE Program, Waseda University, 3-4-1 Okubo, Tokyo 169-8555 (Japan)
We study the superfluid-Mott insulator (SF-MI) transition of spin-1 bosons interacting antiferromagnetically in an optical lattice. Starting from a Bose-Hubbard tight-binding model for spin-1 bosons, we obtain the zero-temperature phase diagram by a mean-field approximation. We find that the MI phase with an even number of atoms per site is a spin singlet state, while the MI phase with an odd number of atoms per site has spin 1 at each site in the limit of t=0, where t is the hopping matrix element. We also show that the superfluid phase is a polar state as in the case for a spin-1 Bose condensate in a harmonic trap. It is found that the MI phase is strongly stabilized against the SF-MI transition when the number of atoms per site is even, due to the formation of singlet pairs. We derive the effective spin Hamiltonian for the MI phase with one atom per site and briefly discuss the spin order in the MI phase.
- OSTI ID:
- 20646422
- Journal Information:
- Physical Review. A, Vol. 70, Issue 4; Other Information: DOI: 10.1103/PhysRevA.70.043628; (c) 2004 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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