Flux Pinning Properties at Low Temperatures in BaHfO₃ Doped SmBa₂Cu₃ Oy Films

BaHfO3(BHO) is attracting attention as a new material forming nanorod as well as BaMO3(BMO: M = Zr, Sn), and it was reported that the flux pinning force of BHO nanorod is effective even at low temperatures. It is essential to understand the flux pinning properties of an APC-doped REBCO film at low temperatures in order to achieve the high-performance superconducting applications. We fabricated 8.4 mol. % BHO-doped SmBa2Cu3Oy(SmBCO) film on LaAlO3(LAO) substrates by pulsed laser deposition method and measured the superconducting properties at 77, 65, 40, and 20 K. As for the magnetic field dependence ofJc, theJcof the BHO-doped SmBCO film was significantly higher than that of the pure SmBCO film at all temperatures. Furthermore, in the magnetic field angular dependence ofJc, the BHO-doped SmBCO film exhibited the peaks ofJcaroundB//cat 77, 65, and 40 K in 3 T. These results suggested that the flux pinning force of BHO nanorod was effective even at 65 and 40 K.