Critical current densities and critical fields of AgMo6S8thin films

Critical currents and upper critical fields were measured on reactively sputtered AgMo6S8films with critical temperatures of up to 9.2K. X-ray measurements on these films, which were grown on sapphire substrates held at temperatures between 800°C and 1000°C, show a preferential orientation of the grains with the 001 direction parallel to the surface of the substrate. The critical field in the perpendicular direction is about 11 tesla when extrapolated to zero temperature. Critical current densities 1×10⁸A/m²were obtained at 6 tesla and 1.2K. Polycrystalline AgMo6S8, prepared by annealing Ag/Mo multilayers in sealed quartz tubes which contain MoS2powder, are used as a comparison to investigate the influence of crystalline order on the critical currents and critical fields of Chevrel phases. We find that although the critical field is larger for the polycrystalline sample, the critical currents are much larger for the preferentially oriented samples.