An Attempt to Arrange BZO Nanorods Into ErBCO Thin Films

We arrayed BaZrO₃ (BZO) nanorods as artificial pinning centers (APCs) into ErBa₂Cu₄O_7-delta (ErBCO) thin films to obtain a higher critical current density (J_c) in a magnetic field. In order to array BZO nanorods in ErBCO thin films, Zr nanoislands were put on SrTiO₃ (STO) substrates as seeds for BZO nanorod growth by using an electron beam lithography (EBL) process, a pulsed laser deposition (PLD) method and a lift off process. After that, we grew ErBCO thin films with BZO nanorods by the PLD method. The Zr nanoislands, arrayed on the STO substrates, were successfully observed by atomic force microscopy (AFM). The Zr nanoislands were 60 ~ 70 nm in diameter and 2 ~ 3 nm in height. Density of the Zr nanoislands was 27.7 mum^-2. Through structural analysis using X-ray diffraction and transmission electron microscopy (TEM) observation, it was confirmed that the ErBCO thin films had c-axis orientation with BZO nanorods. After oxygen annealing process, a critical temperature (T_c) of the film was 88.7 K. J_c measurement of the film in a magnetic field revealed that J_c deterioration was suppressed by introduction of the BZO nanorods. However, a J_c increase at the approximate matching field was not confirmed at around 5.6 times 10^-2 T calculated from density of the Zr nanoislands.