Superfluid and Insulating Phases in an Interacting-Boson Model: Mean-Field Theory and the RPA

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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Abstract

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
Publication:	Europhysics Letters
Publisher:	Institute of Physics
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
URI:	http://eprints.iisc.ac.in/id/eprint/14856

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