SUPERCONDUCTIVITY AND MAGNETISM IN IN-DOPED LEAD-TIN TELLURIDES

Our studies of solid solutions PbzSn1-zTe doped with In have concentra ted on checking for a superconducting transition in the temperature va riation of both the resistivity and the magnetization and of an influe nce on that behaviour of an applied magnetic field. The magnetization of the samples was measured in a SQUID magnetometer using a small fiel d (15 Oe) cooling method. We obtained the dependences of the supercond ucting critical parameters as a function of the In concentration and t he content of isovalent lead. The data for superconductivity correlate with normal state properties and with an influence of the matrix comp osition on the energy band position of the In states. We observed an e nhancement of superconductivity when the Fermi level pinned by the In impurity band enters the heavy hole Sigma-band.