PROPERTIES OF SUPERCONDUCTING LEAD-INDIUM ALLOYS AND GENERALIZED GINZBURG-LANDAU PARAMETER K2

Magnetization measurements have been made on a series of lead-indium alloys containing from 5 to 60 at.% indium. The upper and lower critical fields together with the generalized Ginzburg-Landau parameter κ2 have been obtained at temperatures between 0.2Tc and Tc. Residual resistivities and transition temperatures have also been measured. It is found that κ2 increases with decreasing temperature, the magnitude of the increase being much higher than that expected from existing theory. However, the increase as a function of the Gor'kov impurity parameter ρ closely follows available data for niobium alloys. This result lends support to the view that, despite the present conflict between experiment and theory, an experimental parameter κ2(ρ,A T) does exist which is independent of the detailed characteristics of the alloy system being investigated. Temperature-independent characteristics of the lead-indium system are collected together, and some evidence is found for a modification of the electronic structure at an indium concentration of about 30 at.%. © 1969 The American Physical Society.