Nonperturbative XY -model approach to strong coupling superconductivity in two and three dimensions
نویسندگان
چکیده
For an electron gas with δ-function attraction we investigate the crossover from weakto strong-coupling supercoductivity in two and three dimensions. We derive analytic expressions for the stiffness of phase fluctuations and set up effective XY-models which serve to determine nonperturbatively the temperature of phase decoherence where superconductivity breaks down. We find the transition temperature Tc as a monotonous function of the coupling strength and carrier density both in two and three dimensions, and give analytic formulas for the merging of the temperature of phase decoherence with the temperature of pair formation in the weak-coupling limit. On leave from A.F.Ioffe Physico-Technical Institute Russian Academy of Sciences, Politechnicheskaja str. 26, St. Petersburg, 194021, Russia. Email: [email protected] 2 Email: [email protected] URL: http://www.physik.fu-berlin.de/ ̃kleinert Phone/Fax: 0049 30 8383034.
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