Dependence of the superconducting transition parameters on the solid-solution composition and Te excess in Sn1-zPbzTe : In

A low-temperature (0.4-4.2 K) measurement of the temperature dependences of the resistivity of two series of samples, SnTe1+y and Sn0.8Pb0.2Te1+y soli d solution, doped with 5 at.% In, is reported. The parameters of the superc onducting transition, namely, the critical temperatures T-c and the second critical magnetic field H-c2, and their dependences on tellurium excess (0 less than or equal to y less than or equal to 0.06) have been determined. T he observed variation of the critical parameters with increasing tellurium excess in the samples is associated with a change in the filling by holes o f the indium-impurity resonance states. (C) 1999 American Institute of Phys ics. [S1063-7834(99)00612-7].