Critical current density and flux pinning in an unconventional superconductor

Abstract: The functional dependence of the critical current density on magnetic field, , observed at fixed temperatures in the unconventional type-II superconductor, () alloys, but not the relative magnitude of in different alloy compositions at any given temperature and field, is adequately described by the exponential-decay critical state model. In accordance with the predictions of the Kramer''s flux-pinning model, the peak value of the pinning force density with the exponent and scales with , where is the upper critical field. Irrespective of sample composition and temperature in the superconducting state, the pinning of the flux line lattice (FLL) dominates over the plastic FLL shear. [Copyright &y& Elsevier]