Anisotropy of the resistivity and critical current density of porous vicinalYBa2Cu3O7−δ films

Abstract

The anisotropy of electrical transport properties ofYBa2Cu3O7−δ (YBCO) films containing high density nanopores grown on5°,10° and 20° vicinal substrates was investigated. For porous films in the normal state, the resistivity in thelongitudinal direction is comparable to that of reference YBCO films without nanopores. In addition,the ρc/ρab ratios derived from the resistivities in longitudinal and transverse directions of theporous samples fall in the same range as that of twinned single crystal YBCO. Forthe superconducting state, the pore surfaces provide strong magnetic pins tomagnetic vortices, which leads to significantly increased critical current densityJc along the longitudinal direction as compared to that of the referenceYBCO films. This strong isotropic pore surface pinning also increased theJc along the transverse direction as compared to that of nonporous vicinal YBCO films. Thisresult suggests that the effect of nanopores on the electronic structure of YBCO is minimaland the strong pore surface pinning may provide an effective way to enhanceJc after optimization.