We have measured critical current densities Jc, of superconducting copper molybdenum sulfide prepared by sputtering onto heated sapphire substrates. In addition, we have examined the samples with SEM, TEM, electron microprobe, and x-ray diffraction techniques. Critical currents were measured as a function of external magnetic field and as a function of temperature and sample preparation conditions. We find that a scaling law P = CBc2nf(b) describes our results, where P is the pinning force per unit volume, Bc2 is the upper critical field, b is the reduced field b ≡ B/Bc2, f(b) is a function of b only, and C is a constant of proportionality. Our results fit the flux shearing model of Kramer from relatively low b (≃0.5) to b = 1. Furthermore, applying this model to PbMo6S8, we estimate the critical current density as a function of magnetic field. For example, we predict Jc108 A/m2 at 26 T. From analysis of all experimental data on our samples, we conclude that flux pinning is mainly on excess Mo metal. The Mo is present as a second phase in the predominantly Chevrel-phase CuxMo6S8, while all the Cu metal is included in the Chevrel phase.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Materials Science(all)
- Condensed Matter Physics