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High critical current (Ic) in high magnetic fields (B) with minimal variations with respect to the orientation of the B field is demanded by many applications such as high-field magnets for fusion systems. Motivated by this, this work studies 6 vol. % BaZrO3/YBa2Cu3O7 (BZO/YBCO) multilayer nanocomposite films by stacking two 10 nm thick Ca0.3Y0.7Ba2Cu3O7 (CaY-123) spacers with three BZO/YBCO layers of thickness varied from 50 to 330 nm to make the total film thickness of 150–1000 nm. The Ca diffusion from the spacers into BZO/YBCO was shown to dramatically enhance pinning efficiency of c-axis aligned BZO nanorods, which yields high and almost thickness independent critical current density (Jc) in the BZO/YBCO multilayer nanocomposite films. Remarkably, enhanced Jc was observed in these multilayer samples at a wide temperature range of 20–80 K and magnetic fields up to 9.0 T. In particular, the thicker BZO/YBCO multilayer films outperform their thinner counterparts in both higher value and less anisotropy of Jc at lower temperatures and higher fields. At 20 K and 9.0 T, Ic is up to 654 A/cm-width at B//c in the 6% multilayer (1000 nm) sample, which is close to 753 A/cm-width at B//ab due to the intrinsic pinning. This result illustrates the critical role of the Ca cation diffusion into the YBCO lattice in achieving high and isotropic pinning in thick BZO/YBCO multilayer films. 

One-dimensional artificial pinning centers (1D-APCs) in YBa2Cu3O7-x nanocomposite films provide strong collective pinning at magnetic field B//c-axis. In this work, we reveal a 1D-APC/YBa2Cu3O7-x interface is preferred for high pinning efficiency of individual 1D-APCs including BaHfO3 and BaZrO3. The coherent 1D-APC/YBa2Cu3O7-x interface may be obtained via either growth of the nanocomposite films at optimal condition or Ca-diffusion to dynamically reduce the interface strain during the nanocomposite film growth. Interestingly, the high pinning efficiency of the 1D-APCs with coherent interfaces with YBCO not only lead to a high critical current density (Jc) in magnetic fields up to 9.0 T at H//c-axis but also enhanced Jc over a larger angular range when H is away from H//c-axis up to θ=60-80 degree than that in the case the interface is defective. This result suggests the importance of understanding and engineering the APC/YBCO interface for optimal pinning in nanocomposite films. 

Deposition temperature is an important parameter to control in pulsed laser deposition of thin films, as it affects the ad-atom mobility and diffusion in regards to film growth. Increased growth temperature can also result in increased stacking fault densities in YBa2Cu3O7- (YBCO) films. This research investigates the influence of deposition temperature on the critical current density, critical temperature, and the microstructure of YBCO thin films double doped with BaHfO3 and Y2O3. A KrF excimer laser was used to produce thin films of YBCO doped with 4 vol.% BaHfO3 and 3 vol. % Y2O3 on LaAlO3 (LAO) substrates at various deposition temperatures from 790 - 825. The growth temperature influence on the flux pinning landscape and Jc (H,T,) properties (T = 5 - 77K, H = 0 - 9T, = 0 -180) of these films will be presented.