Thickness dependence of structural and superconducting properties of Co-doped BaFe2As2 coated conductors

Zhongtang Xu; Chiheng Dong; Chuanbing Cai; Pusheng Yuan; Yanwei Ma

doi:10.1016/j.isci.2021.102922

Thickness dependence of structural and superconducting properties of Co-doped BaFe₂As₂ coated conductors

iScience. 2021 Jul 30;24(8):102922. doi: 10.1016/j.isci.2021.102922. eCollection 2021 Aug 20.

Authors

Zhongtang Xu¹, Chiheng Dong¹, Chuanbing Cai², Pusheng Yuan³, Yanwei Ma^{1

4}

Affiliations

¹ Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China.
² Research Center for Superconductors and Applied Technologies, Shanghai University, Shanghai 200444, China.
³ State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, China.
⁴ University of Chinese Academy of Sciences, Beijing 100049, China.

Abstract

High-quality Co-doped BaFe₂As₂ thin films with thickness up to 2 μm were realized on flexible metal tapes with LaMnO₃ as buffer layers fabricated by an ion beam-assisted deposition technique. Structural analysis indicates that increasing thickness does not compromise the film crystallinity, except for a small amount of impurities. Two types of thickness dependence of critical current density (J _c) were found: one is almost thickness independent in the range of 0.6-1.5 μm and the other is highly thickness dependent. In addition, the maximum value for crucial current I _c at 9 T and 4.2 K is about 55 A/12 mm-W for the 1.5-μm-thick film. Anisotropic Ginzburg-Landau scaling demonstrates that dominant pinning centers develop from correlated to uncorrelated with increasing film thickness. The further theoretical analysis shows that with film thickness increasing the pinning mechanism evolves progressively from a δl pinning to the δT _c pinning mechanism.

Keywords: Condensed matter properties; Energy materials; Solid state physics; Superconductivity.