THE EFFECT OF CO ON THE SUPERCONDUCTING AND MAGNETIC-ORDERING TEMPERATURES IN ERNI2B2C

We have investigated the influence of Co substitution an superconducti vity (SC) and magnetism in the intermetallic ErNi2-xCoxB2C system by a c and dc magnetic measurements. For ErNi2B2C, T-C = 10.9 K and T-N = 6 .2 K (T-C>T-N). For x = 0.05, T-C is reduced to 4.7 K, and T-N increas es to 8.2 K; thus (T-N > T-C). For x = 0.2 and 0.5, the compounds are not SC, and T-N increases to 10.9 and 14.8 K, respectively. For all Er Ni1.8M0.2B2C (M = Pt, Pd and Co) we obtain T-N similar to 11(1) K rega rdless of M.