Spin fluctuations in metallic glasses Zr sub 75 (Ni sub x Fe sub 1-x ) sub 25 at ambient and higher pressures

• Published in: Physical review. B, Condensed matter Condensed matter, 1995-10, Vol.52 (13), p.9674-9678
• Main Authors: Hamed, F, Razavi, F S, Bose, S K, Startseva, T
• Format: Article
• Language: English
• ISSN: 0163-1829

The superconducting properties of metallic glasses Zr sub 75 (Ni sub x Fe sub 1-x ) sub 25 (x=0, 0.25, 0.50, 0.75, 1.0) were studied both at ambient pressure and under quasi-hydrostatic pressure up to 8 GPa (80 kbar). To obtain information on the spin fluctuation parameter lambda sub e-SF the following measurements were carried out: the d.c. magnetic susceptibility, the upper critical field at the ambient pressure superconducting transition temperature T sub c (P=1 bar), mass density and room temperature resistivity. From the pressure dependence of the superconducting transition temperature T sub c (P) in Cu sub 25 Zr sub 75 glass we estimate the volume derivative of the electron-phonon (e-ph) coupling parameter lambda sub e-ph in this alloy using the McMillan equation. This is used as a reference value for the volume derivative of lambda sub e-ph in the Zr sub 75 (Ni sub x Fe sub 1-x ) sub 25 alloys. Using the modified McMilan equation, which includes spin fluctuation effects and the above reference value for the volume derivative of the e-ph coupling parameter, we determine lambda - sub e-ph , the electron-spin fluctuation coupling parameter lambda sub SF and the rate of suppression of spin fluctuations with the pressure (d ln lambda sub SF /d ln V) as a function of Fe concentration in these alloys. Both spin fluctuations and the rate of suppression of spin fluctuations with pressure (d ln lambda sub SF /d ln V) are found to increase with higher Fe concentration in these alloys.