Enhanced flux pinning and critical current density via incorporation of self-assembled rare-earth barium tantalate nanocolumns within YBa_2Cu_3O_(7-δ) films

摘要

We report rare-earth barium tantalates, Ba_2RETaO_6 (BRETO, RE=rare earth elements) as promising pinning additives for superior flux pinning in YBa_2Cu_3O_(7-δ) (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. YBCO+ 4 vol % Ba_2GdTaO_6 films show similar T_c to that of an undoped film of ～88.3 K, a higher self-field J_c of 3.8 MA/cm~2 at 77 K, and improved in-field J_c higher by a factor of 1.5-6 over entire magnetic field and angular ranges.