Flux pinning in high-temperature superconducting multicore wires based on Bi2Sr2CaCu2O<i>x</i>

Abstract

Using the powder-in-tube technique superconducting 19-core wires have been produced with several diameters (down to 1/10 mm) and a length of some hundred meters. These wires show critical current densities of about 13500 A/cm2 in zero magnetic field and 6000 A/cm2 in a parallel field of 10 T at 4.2 K, respectively. For high magnetic field application it is necessary to understand the flux pinning mechanism. For this purpose the dissipative flux motion below Tc has been studied. The results of dc measurements were parametrized in the framework of flux creep. Using the Anderson model [published in Phys. Rev. Lett. 9, 309 (1962)], we find an activation energy inversely proportional to the square root of the magnetic field.