Incollection,
Peculiarities of the critical current and magneto-resistance sign change
Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)
Abstract
A combined effect of two irreversibility mechanisms (the surface barrier and the bulk pinning of the magnetic flux) is investigated on the magnetic field dependence of a critical current Jc in type-II superconductors. It is shown, that there exists an anomalous peak of Jc in the weak magnetic field range. Such an additional peak illustrates the combined influence of both surface barrier and bulk pinning mechanisms, which are extremely sensitive to the transport current density distribution in a superconductor. In addition, we have calculated the voltage-current characteristics of bulk superconducting sample, possessing a surface barrier. The effect of the differential magneto-resistance sign change of a superconducting sample is reported. The physical mechanism responsible for the existence of this effect is discussed in terms of the competition between two modes of the energy dissipation in the presence of a supercurrent in a superconductor(the vortex motion and annihilation).
