Influence of Fermi surface topology on the pressure dependence ofT c for indium and dilute indium alloys

The pressure dependence of the superconducting transition temperature for In, In-Cd (to 3.5 at.%), and In-Pb (to 12 at.%) has been determined to 24 kbar. A small deviation from a linear dependence ofT _c on volume compression is found for indium. Alloying with Cd and Pb modified this nonlinear contribution, which is interpreted as arising from changes in the Fermi surface topology. In all, four transitions are identified and their possible origins, based upon the known Fermi surface of indium, are discussed.Research sponsored by the Air Force Office of Scientific Research, Air Force Systems Command, USAF, under AFOSR contract number AFOSR-F44620-72-C-0017.