Transport properties in a superconducting proximity sandwich with magnetic impurities

Abstract

The thermal conductivity and ultrasonic attenuation rate are calculated numerically in a superconducting proximity sandwich containing magnetic impurities on the normal-metal side. The calculations are carried out on the basis of the theory given by Machida, in which the McMillan tunneling model is adopted to describe the proximity effect. In the limit of a thick superconducting film, analytical expressions are obtained near the transition temperature T = Tc and near T = O. As in the case of a bulk superconductor with magnetic impurities, the existence of a bound state within an effective energy gap gives a significant effect on the transport properties. The calculation is compared with experiment on the thermal conductivity for AgMn/Pb sandwiches, and reasonable agreement is obtained between them.

Transport properties in a superconducting proximity sandwich. Kondo effect

“…In an SNIS1 junction, the maximum dc Josephson current J(T) can be (13) where ge ~ is the trigamma function. The suggestion was first made by McMillan 2~ that the Josephson current in a proximity-effect junction could determine A or F at the tunneling surface.…”

“…We calculated the maximum dc Josephson current and thermal conductivity for a proximity system, and found satisfactory agreement with experiments. 12,13 In the calculations, however, the Kondo effect is not taken into account, which could give rise to the reentrance of superconductivity also in the proximity-effect regime. 8…”