Simultaneous achievement of high Jc and suppressed Jc anisotropy by hybrid pinning in YBa2Cu3O7 three-phase-nanocomposite film

Abstract

Nanoscale pinning centers are introduced into YBa2Cu3O7 (YBCO) films and tapes to improve vortex pinning and critical current density (Jc) for coated conductor application. While pinning with a single type of pinning center has been mainly investigated, hybrid pinning with multiple types of pinning center is expected to be more promising for simultaneously achieving high Jc values and suppressing Jc anisotropy. In the present study, a three-phase-nanocomposite film consisting of an YBCO matrix, BaHfO3 nanorods and Y-O nanoparticles was fabricated. A global pinning force maximum (Fp,max, where Fp = JcB) of 1.57 TN m−3 at 4.2 K, which is as high as the record level of Fp,max, was achieved by the hybrid pinning of BaHfO3 nanorods and Y-O nanoparticles. Furthermore, the hybrid pinning improved the angular dependence of Jc. The pinning contribution from nanoparticles increased with lowering temperature, which can explain the high Jc at low temperature. Thus, the present study successfully demonstrates a highly effective structure that can simultaneously achieve suppressed Jc anisotropy and a record level of Jc.