Localized superconductivity

D. van der Marel; J. E. Mooij

doi:10.1103/PhysRevB.45.9940

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Localized superconductivity

D. van der Marel, J. E. Mooij

DOI 10.1103/PhysRevB.45.9940 · Physical Review B

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Abstract

From a self-consistent solution of the mean-field theory describing a negative-U impurity embedded in a tight-binding band of fermions, we derive the conditions necessary for the formation of an off-diagonally ordered local moment in contact with a continuum of unpaired electrons. We calculate the electron removal and addition spectra and show that the spectrum is gapless, although in the ordered state some spectral weight is shifted away from the region around the Fermi level. We discuss the temperature dependence and the proximity-induced distance dependence of the order parameter and discusss the coupling between local moments as a function of distance and temperature. We predict that for a sufficiently strong attractive interaction the superconducting phase transition occurs between a state with off-diagonal long-range order below Tc and off-diagonal short-range order above Tc.