Bethe Ansatz Approach to the Thermodynamics of Superconducting Magnetic Alloys

Valery I. Rupasov

doi:10.1103/PhysRevLett.80.3368

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Bethe Ansatz Approach to the Thermodynamics of Superconducting Magnetic Alloys

Valery I. Rupasov

DOI 10.1103/PhysRevLett.80.3368 · Physical Review Letters

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Abstract

We derive thermodynamic Bethe ansatz equations for a model describing a U→∞ Anderson impurity embedded in a BCS superconductor. The equations are solved analytically in the zero-temperature limit, T=0. It is shown that the impurities depress superconductivity in the Kondo limit; however, at T=0 the system remains in the superconducting state for any impurity concentration. In the mixed-valence regime, an impurity contribution to the density of states of the system near the Fermi level overcompensates a Cooper pairs weakening, and superconductivity is enhanced.