Superconducting transition in a mixture of bosons and fermions

E. Piegari; S. Caprara

doi:10.1103/PhysRevB.67.214503

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Superconducting transition in a mixture of bosons and fermions

E. Piegari, S. Caprara

DOI 10.1103/PhysRevB.67.214503 · Physical Review B

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Abstract

By means of the functional-integral formulation we discuss the occurrence of superconductivity resulting from Bose-Einstein condensation within a model describing preformed pairs which coexist in thermal equilibrium with unpaired fermions. At saddle-point level we study the thermodynamic properties of the model as functions of the boson excitation energy ν, discussing the results in connection with the phenomenology of the pseudogap state of the superconducting cuprates. For temperatures above the Bose-Einstein condensation temperature Tc we also analyze the effects of Gaussian fluctuations on the critical temperature and on the boson spectrum. Finally, we compare the bosonic effective action which controls thermal fluctuations of the mixture to the time-dependent Ginzburg-Landau functional of an interacting fermionic system at intermediate coupling.