An evidence for the s-wave superconductivity of an itinerant weak antiferromagnet CuCo2S4

The electronic and magnetic properties of superconducting CuCo2S4 have been investigated with (CU)-C-63 and Co-59 NMR and 59Co PQR measurements. In the normal state, the temperature dependences of the Knight shift and the relaxation rate of T-1(-1) Cu-63 indicate that both the uniform susceptibility chi(0) and the staggered susceptibility chi(Q) (Q being AF wave vector) exhibit CW-type behavior with theta = - 300 K and T-N = 23 K, respectively. In the superconducting state, T-1(-1) of Co-59 exhibits the BCS coherence peak just below T-S = 4.4 K and then decreases in proportion to exp( - 2.07T/T-s), providing an evidence for a strongly coupled s-wave superconductor. (C) 2000 Elsevier Science B.V. All rights reserved.