Critical current density in Ag/YBa₂Cu₃O_xand PrBa₂Cu₃O_y/YBa₂Cu₃O_xmultilayers

Abstract

One of successful methods of introducing artificial pinning centres in superconducting films is by alternating layers of superconducting material and incomplete layers (planar distributions of nanodots) of other materials (quasi-superlattice or quasi-multilayer approach). Most of the work on artificial pinning centres has been done on thin YBa2Cu3Ox (YBCO) films and a large variety of quasi-multilayer materials have been explored. It is still difficult to justify the choice of a quasi-multilayer material for particular superconducting applications. One of the properties to be taken into account is compatibility of the crystal lattice of YBCO and the quasi-superlattice material. Here we compare the superconducting behaviour of two very different quasi-multilayers: one with very similar crystal lattices of nanodots and YBCO: PrBa2Cu3Oy (PBCO)/YBCO, and another one with very different, Ag/YBCO. We found that the difference between crystal lattices strongly affects superconducting properties of quasi-multilayers and leads to different types of pinning in the films.