Effect of elastic strain and stress on the superconducting transition temperature of quench-condensed films

The volume dependence of the superconducting transition temperature Tsub(c) of amorphous and highly disordered films is investigated by bending the film substrate. The volume coefficient d ln Tsub(c)/d ln V of annealed Sn and Pb films agrees with the volume coefficient known from hydrostatic pressure experiments. This bending technique is applied to superconducting modifications which can be produced only by quench condensation onto a substrate at liquid helium temperature. Amorphous films such as Bi, Ga, Sn90Cu10 and Pbsub(x)Bisub(1-x), as well as highly disordered Sn and Pb films are investigated. The relations found between the volume coefficient, the electron-phonon coupling constant lambda and the Grueneisen parameter γsub(G) are in reasonable agreement with the volume dependence of Tsub(c) for non-transition metals, obtained on the basis of the McMillan equation. In particular, the results represent an expansion of this kind of investigation to very strong-coupling superconductors. (orig.)