Enhancing magnetic pinning by BaZrO3 nanorods forming coherent interface by strain-directed Ca-doping in YBa2Cu3O7−x nanocomposite films. (7th September 2021)

• Record Type: Journal Article
• Authors: Ogunjimi, Victor; Sebastian, Mary Ann; Zhang, Di; Gautam, Bibek; Jian, Jie; Huang, Jijie; Zhang, Yifan; Haugan, Timothy; Wang, Haiyan; Wu, Judy
• Is Part Of: Superconductor science & technology. Volume 34:Number 10(2021)
• Publication Date: 2021-09-07
• Subjects: YBCO nanocomposites -- coherent interface -- vortex pinning efficiency -- 1D artificial pinning center; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/1361-6668/ac1fd3
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: BaZrO3 (BZO) one-dimensional artificial pinning centers (1D-APCs) aligned along the c -axis of the YBa2 Cu3 O7 (YBCO) have been adopted to enhance the magnetic vortex pinning in BZO/YBCO nanocomposite films. However, the pinning force density F p of the BZO 1D-APCs remains moderate at temperatures near 77 K. A hypothesis of the major limiting factor is the defective BZO 1D-APCs/YBCO interface as a direct consequence of the large interfacial strain originated from the BZO/YBCO lattice mismatch of ∼7.7%. Herein, we explore enlarging the c -axis of the YBCO dynamically to reduce the lattice mismatch and hence to prevent formation of the defective BZO 1D-APCs/YBCO interface. Specifically, the c- axis enlargement was achieved by partial replacement of Cu with Ca on the YBCO lattice using strain-directed Ca diffusion into YBCO from two Ca0.3 Y0.7 Ba2 Cu3 O7− x (CaY-123) spacers of only 10 nm in thickness inserted into the 2 vol% BZO 1D-APC/YBCO nanocomposite thin films of ∼150 nm in total thickness. The achieved elongated c -axis is attributed to the formation of stacking faults induced by Ca-replacement of Cu on YBCO lattice. The reduced BZO/YBCO lattice mismatch allows formation of a coherent BZO 1D-APC/YBCO interface with negligible defects. This leads to an enhanced F p value up to 98 GN m −3 at 65 K, which is 70% higher than that of the reference 2 vol% BZO 1D-APC/YBCO sample. Furthermore, the benefit of the enhanced pinning of the BZO 1D-APCs with a coherent interface with YBCO can be extended to a large angular range of the magnetic field orientation. This study reveals the significant effect of the BZO/YBCO interface on the pinning efficiency of BZO 1D-APCs and provides a promising approach to achieve a coherent interface in BZO/YBCO nanocomposite films.