Effect of localised modes on spin fluctuations and transition temperatures of Zr metallic glass superconductors

Abstract

The effects of localised phonons on transition temperatures in three binary metallic systems Ni-Zr, Co-Zr and Fe-Zr have been theoretically evaluated from the renormalised electron-phonon parameter and compared with their metallic glass counterparts. The influence of spin fluctuations has also been evaluated within the range 0.50<x<0.71 for Ni-Zr, 0.53<x<0.70 for Co-Zr, and 0.72<x<0.80 for Fe-Zr compounds (x being the concentration of Zr). The results obtained using a modified form of the McMillan equation clearly show the influence of spin fluctuations in reducing the superconducting transition temperatures. The transition temperatures of these binary metallic compounds have been found to be very sensitive to the variations of concentrations of Ni, Co and Fe in Zr, and agree well with the reported values at definite concentrations, indicating a possibility of phase transition in these systems.