Comparison of projected critical currents in PbMo₆S₈ and Nb₃Ge

Critical current densities, J_c, of sputtered Chevrel phase PbMo₆S₈ films have been measured as a function of field to 19 T at several temperatures. The pinning forces were found to obey a scaling law. Assuming an effective upper critical field B_c2 = 45 T, an effective critical temperature T_c = 13 K, together with empirical estimates of numerical factors in the scaling law, we estimate the upper limits for critical current density J_c in PbMo₆S₈. Comparisons are made to estimates of J_c for Nb₃Ge at 4.2 K. A crossover of J_c 10⁸ A m^-2) vs B is found for B of the order of 25 to 30 T. Below this point, Nb₃Ge is projected to have a higher critical current density. Thus practical use of Chevrel materials in high field magnets only appears to be competitive with Nb₃Ge for fields above 25 to 30 T.