Pressure dependence of spin fluctuations in metallic glasses Ni25Zr75 and Fe100-xZrx (x=75,80)

The superconducting transition temperature Tc of metallic glasses Fe20Zr80, Fe25Zr75, and Cu25Zr75 were measured under quasihydrostatic pressure up to 10 GPa. The volume (pressure) dependence of the electron-phonon coupling parameter, e-ph, for Cu25Zr75 was calculated using the McMillan equation. Using this volume dependence of e-ph and the modified McMillan equation, which incorporates spin fluctuations, we determined the volume dependence of the spin-fluctuation parameter, SF, in Ni25Zr75 and Fe100-xZrx (x=80, 75). It was found that with increasing pressure spin fluctuations are suppressed at a faster rate in Fe100-xZrx as the Fe concentration is increased. The rate of suppression of spin fluctuations with pressure was also found to be higher in the Fe-Zr glasses than in Ni-Zr glasses of similar composition.