Towards Isotropic Vortex Pinning in YBCO Films with Double-doping BHO-Y2O3 and BZO-Y2O3 Artificial Pining Centers

International Cryogenic Materials Conference 2017

Gautam, Bibek^1 ; Sebastian, Mary Ann^2 ; Chen, Shihong^1 ; Haugan, Timothy^2 ; Chen, Yanbin^3 ; Xing, Zhongwen^4 ; Prestigiacomo, Joseph^5 ; Osofsky, Mike^5 ; Wu, Judy^1

Department of Physics and Astronomy, University of Kansas, Lawrence

KS

66045, United States^1

U.S. Air Force Research Laboratory, Propulsion Directorate, WPAFB, OH

45433, United States^2

Physics Department at Nanjing University, Nanjing, JIANGSU

210093, China^3

College of Engineering and Applied Science, Nanjing University, Nanjing, JIANGSU

210093, China^4

US Naval Research Laboratory, 4555 Overlook Ave, SW Washington

DC

20375, United States^5

关键词: Artificial pinning centers;    Comparative studies;    Elastic strain;    Epitaxial thin films;    High-field applications;    Secondary dopant;    Transport critical current density;    Vortex pinning;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/279/1/012030/pdf
DOI  :  10.1088/1757-899X/279/1/012030

来源: IOP

【 摘 要 】

Strong and isotropic vortex pinning landscape is demanded for high field applications of YaBa2Cu3O7-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 Jc(H, θ) 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 Jcpeak at H//c-axis and hence more isotropic Jc(θ) than their BZO DD counterparts. At 9.0 T, the variation of the Jcacross the entire θ 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 Y2O3leads to increased ab-plane aligned BHO APCs and hence enhanced Jcat H//ab-plane.