Jc enhancement in YBa2Cu3Ox thin films by introduction of one-dimensional artificial pinning centers

摘要

A novel technology to introduce artificial pinning centers (APCs) into YBa2Cu3O7-δ (YBCO) thin films prepared by pulsed laser deposition (PLD) was investigated for a drastic improvement of Jc in the films. Linear-like defects (one-dimensional APCs) were introduced perpendicular to the surface of the c-axis oriented films during the deposition process by using distributed Y2O3 nano-islands on substrates. The density of nano-islands was varied within 0.8-1.2×1010/cm2 by PLD. A normalized resistivity as a function of temperature in magnetic fields shows a sharper resistivity drop for the film with APC, compared to pure YBCO film. Jc of the film with APC was also increased to 0.12 MA/cm2 (77 K, B//c, 5 T), which was about two times higher than that of the pure YBCO film. The film had a very large Jc peak when the field was applied close to the c-axis. The peak Jc increased with the number density of Y2O3 nano-islands. This indicates that strong APCs parallel to the c-axis were incorporated into the YBCO film.