Monday, January 30, 2012

1111.0239 (Gunnar Moller et al.)

Correlated phases of bosons in the flat lowest band of the dice lattice    [PDF]

Gunnar Moller, Nigel R. Cooper
We study correlated phases occurring in the flat lowest band of the dice
lattice model at flux density one half. We discuss how to realize the dice
lattice model, also referred to as the T_3 lattice, in cold atomic gases. We
construct the projection of the model to the lowest dice band, which yields a
Hubbard-Hamiltonian with interaction-assisted hopping processes. We solve this
model for bosons in two limits. In the limit of large density, we use
Gross-Pitaevskii mean-field theory to reveal time-reversal symmetry breaking
vortex lattice phases. At low density, we use exact diagonalization to identify
three stable phases at fractional filling factors \nu of the lowest band,
including a classical crystal at \nu=1/3, a supersolid state at \nu=1/2 and a
Mott insulator at \nu=1.
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