Towards Isotropic Vortex Pinning in YBCO Films with Double-Doping BHO-Y2O3 and BZO- Y2O3 Artificial Pining Centers
Abstract
Strong and isotropic vortex pinning landscape is demanded for high field applications of YaBa(2)Cu(3)O(7-x) (YBCO) epitaxial thin films. Double-doping (DD) of artificial pinning centers (APCs) of mixed morphologies has been identified as a viable approach for this purpose. This work presents a comparative study on the transport critical current density J(c) (H, theta) of 3.0 vol. Y2O3 2.0 (or 6.0) vol. BaZrO3 (BZO DD) and 3.0 vol. Y2O3 2.0 (or 6.0) vol. BaHfO3 (BHO DD) films. Based on the elastic strain model, BaHfO3 (BHO) nanorods have lower rigidity than their BaZrO3 (BZO) counterparts, which means their c-axis alignment is more susceptible to the local strain generated by the secondary dopant of Y2O3. Considering the increasing strain field with higher BZO (or BHO doping), the higher susceptibility may result in a large portion of the BHO APCs moving away from perfect c-axis alignment and enhancing isotropic pinning with respect to the H orientation. This is confirmed since the BHO DD films illustrate a less pronounced Jc peak at H//c-axis and hence more isotropic J(c)(theta) than their BZO DD counterparts. At 9.0 T, the variation of the J(c) across the entire. range (0-90 degree) is less than 18 for the BHO DD film, in contrast to about 100 for the 2.0 vol. BZO DD counterpart. At the higher BHO concentration of 6.0 vol. , this higher tunability of the Y2O3 leads to increased ab-plane aligned BHO APCs and hence enhanced J(c) at H//ab-plane.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 09, 2017
- Accession Number
- AD1114820
Entities
People
- Bibek Gautam
- Joseph C Prestigiacomo
- Judy Wu
- Mary Sebastian
- Mike Osofsky
- Shihong Chen
- Timothy J. Haugan
- Yanbin Chen
- Zhongwen Xing
Organizations
- United States Naval Research Laboratory