Integrated nanotechnology of pinning centers in YBa2Cu3Ox films

A controlled pinning change from the ab-plane dominant to the c-axis dominant has been achieved in a novel method of nanostructured YBa2Cu3Ox (YBCO) growth. The method is a synchronous self-assembly of BaZrO3 (BZO) and Ag-assisted YBCO nanothreads. The formation of entangled nanothreads increases the critical current density while keeping the critical temperature close to that in pure YBCO films. The nanothreads extend through the whole thickness of thick films, making the method suitable for increasing total critical current density per centimeter of width (Ic-w). Two growth mechanisms, the formation of BZO nanorods and YBCO nanocolumns, complement each other, form a coherent structure and produce samples with strong correlated pinning. In addition to the increase in Ic-w, correlated pinning leads to an increase in vortex melting temperature in a wide range of magnetic fields. The films grown by this method have high Ic-w both in low magnetic fields along the c axis and high magnetic fields in the ab plane of YBCO. Such a superconductor would be suitable for both cable and magnet applications.