Sheshadri, K and Krishnamurthy, HR and Pandit, R and Ramakrishnan, TV (1993) Superfluid and Insulating Phases in an Interacting-Boson Model: Mean-Field Theory and the RPA. In: Europhysics Letters, 22 (4). pp. 257-263.
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The bosonic Hubbard model is studied via a simple mesn-field theory. At zero temperature, in addition to yielding a phase diagram that is qualitatively correct, namely a superfluid phase for non-integer fillings and a Mott transition from a superfluid to an insulating phase for integer fillings, this theory gives results that are in good agreement with Monte Carlo simulations. In particular, the superfluid fraction obtained as a function of the interaction strength U for both integer and non-integer fillings is close to the simulation results. In all phases the excitation spectra are obtained by using the random phase approximation (RPA): the spectrum has a gap in the insulating phase and is gapless (and linear at small wave vectors) in the superfluid phase. Analytic results are presented in the limits of large U and small superfluid density. Finite-temperature phase diagrams and the Motbinsulator-normal-phase crossover are also descriied.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to Institute of Physics.|
|Department/Centre:||Division of Physical & Mathematical Sciences > Physics|
|Date Deposited:||08 Jul 2008|
|Last Modified:||19 Sep 2010 04:47|
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