Upper critical field of copper molybdenum sulfide

The upper critical field B_c2(T) of sintered and sputtered copper molybdenum sulfide Cu_xMo₆S₈ was measured. It was found to be higher than the highest prediction for a type II superconductor in the dirty limit with no paramagnetic limiting and with weak isotropic electron phonon coupling. The enhancement of B_c2(T) is probably due either to anisotrophy or to purity or to both. Other ternary molybdenum sulfides appear to show similar anomalies.