Effects of structural relaxation on a superconducting glassy Cu-Zr alloy

Abstract

Measurements of the low-temperature specific heat, in different magnetic fields, are presented for the metallic glass Cu0.46Zr0.54 in the as-quenched and fully relaxed states. The data are analysed in terms of the theory of type II superconductivity and the variations of the relevant parameters are discussed. Structural relaxation changes the electron density of states at the Fermi level, the Debye temperature and the average of the square of the electron-phonon matrix elements in the opposite direction to that of crystallisation. The most strongly affected quantity is the electron-phonon interaction. In the two different glassy states, fluctuation contributions to the specific heat are observed in the critical region which exhibit contrasting behaviour in an applied magnetic field just below the transition points. An explanation is suggested in terms of a partial suppression by the structural relaxation of structural defects of the type and size of those which have been identified recently in glassy metals by a computer simulation.