SUPERCONDUCTIVITY IN THE PSEUDOQUARTERNARY SYSTEM Y(NI1-XCOX)(2)B2C

The superconducting transition temperatures of the quarternary alloy s ystem Y(Ni1-xCox)(2)B2C, determined by ac susceptibility measurements down to 1.2 K are reported. We find a decrease of T-c from 15.0 K for the pure Ni compound to T-c < 1.2 K for x > 0.2, with growing Co conte nt. SQUID measurements show that magnetic pairbreaking is not responsi ble for the decrease in T-c. The results are discussed in a rigid band model and in the Kaiser theory of nonmagnetic resonant states.