Enhanced flux pinning and critical current density via incorporation of self-assembled rare-earth barium tantalate nanocolumns withinYBa2Cu3O7−δfilms

Abstract

We report rare-earth barium tantalates, ${\text{Ba}}_{2}RE{\text{TaO}}_{6}$ (BRETO, $RE=\text{rare}$ earth elements) as promising pinning additives for superior flux pinning in ${\text{YBa}}_{2}{\text{Cu}}_{3}{\text{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ (YBCO) films. BRETO compounds have excellent chemical inertness to and large lattice mismatch with YBCO. This results in phase separation and strain minimization driven self-assembly of BRETO nanocolumns within YBCO films. $\text{YBCO}+4\text{ }\text{vol}\text{ }\mathrm{%}$ ${\text{Ba}}_{2}{\text{GdTaO}}_{6}$ films show similar ${T}_{\text{c}}$ to that of an undoped film of $\ensuremath{\sim}88.3\text{ }\text{K}$, a higher self-field ${J}_{c}$ of $3.8\text{ }\text{MA}/{\text{cm}}^{2}$ at 77 K, and improved in-field ${J}_{\text{c}}$ higher by a factor of 1.5--6 over entire magnetic field and angular ranges.