Clarification and mitigation of marked Jc decrease at low magnetic fields of BaHfO3-doped SmBaCuO3 thin films deposited on seed layer

Abstract In accordance with the results of our previous research, a low-temperature growth (LTG) technique is effective for expanding the lower growth temperature region of c -axis-orientated SmBa 2 Cu 3 O y (SmBCO) thin films. However, BaHfO 3 (BHO)-doped LTG films show a marked decrease in J c at low magnetic fields compared with conventional PLD films. In this study, we aimed to clarify the mechanism of J c decrease and investigated the thickness dependence of the seed layer on the (LaAlO 3 ) 0.3 (Sr 2 AlTaO 6 ) 0.7 (LSAT) (100) single crystal. The obtained results indicate that J c decreased at low magnetic fields as the thickness of the seed layer increased. It is suggested that flux line kinks produced by flux motion in the seed layer would lead to the depinning of flux lines from BHO nanorods in the upper layer. Thus, we added Y 2 O 3 into the seed layer to trap flux lines in the seed layer. Consequently, we improved J c in the low magnetic field region even in the films prepared by using the LTG technique.