STRONG DEPRESSION OF TC IN SUPERCONDUCTING DISORDERED CU50ZR50 WITH DILUTE MAGNETIC-IMPURITIES

Dilute magnetic impurities in a superconducting metallic glass are investigated. For two alloys with 1650 ppm of iron and with 11 ppm of manganese in a Zr50Cu50 host, there is a comparable reduction of the superconducting T(c) by 40-50%. The upper critical field is measured for both samples down to t = T/T(c) < 0.15 and the magnetic susceptibility is measured for the manganese-doped sample down to 2 K. From these measurements we conclude that there is strong pairbreaking in both alloys, which appears to decrease slightly with decreasing temperature. The manganese impurity has a spin of S = 2 and a Curie-Weiss temperature of - 3.8 K, and an unusually strong effect on T(c) with a depression rate of about 350 K (at.%)-1.