Comparison Study of the Flux Pinning Enhancement of YBa2Cu3O7−δ Thin Films With BaHfO3 + Y2O3 Single- and Mixed-Phase Additions

Abstract

Incorporating nano-scale insulating phases to YBa2Cu3O7−δ (YBCO) superconductor thin films enhances flux pinning by combining different pinning mechanisms, which in turn increases the current density. This research explores the effects of addition of the non-reactive phases of barium hafnate (BHO) and yttrium oxide Y2O3. Pulsed laser deposition (PLD) produces thin films on SrTiO3 (STO) substrates at various deposition temperatures ranging from 790 °C to 840 °C. PLD target compositions vary the volume percent of BHO from 2 to 6 vol% while maintaining 3 vol% Y2O3 and the remaining vol% YBCO. Examining the microstructure through SEM, TEM, and XRD analyses provides insight into the impact of the additions of BHO and Y2O3 on the YBCO thin films’ magnetic and transport current densities measured with an applied field parallel to the c and ab directions, and on the films’ critical temperature measurements. The Y2O3 additions decrease the variability in the current density between the c and ab directions, which is an important aspect to consider in applications, such as for HTS wires for motors.