The influence of the geometric characteristics of nanorods on the flux pinning in high-performance BaMO₃-doped SmBa₂Cu₃O_<i>y</i>films (M = Hf, Sn)

Abstract

Recently, the BaHfO3 (BHO) nanorod has attracted attention as a new c-axis-correlated pinning center in REBa2Cu3Oy films. We fabricated SmBa2Cu3Oy (SmBCO) films with BHO nanorods using an alternating-targets technique with pulsed laser deposition on single-crystal LaAlO3(100) substrates, and then compared the microstructure and flux pinning properties with those of BaSnO3 (BSO)-doped SmBCO films. Transmission electron microscopy observations indicated that the BHO and BSO nanorods both grew straight, but the inclination of the BHO nanorods from the c-axis of the SmBCO was less than that of the BSO nanorods. The inclination had a strong influence on the flux pinning property. The flux pinning force of the BHO-doped SmBCO film ( with Jc = 2.0 MA cm−2 at 77 K under 1.4 T) became stronger than that of the BSO-doped SmBCO film ( with Jc = 1.4 MA cm−2 at 77 K under 1.8 T) due to the shape of the BHO nanorods without inclining.