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1. Enabling coherent BaZrO ₃ nanorods/YBa ₂ Cu ₃ O _7−x interface through dynamic lattice enlargement in vertical epitaxy of BaZrO ₃ /YBa ₂ Cu ₃ O _7−x nanocomposites

   https://doi.org/10.1088/1361-6668/ac4aff  

   Wu, Judy Z ; Ogunjimi, Victor ; Sebastian, Mary Ann ; Zhang, Di ; Jian, Jie ; Huang, Jijie ; Zhang, Yifan ; Gautam, Bibek ; Haugan, Timothy ; Wang, Haiyan ( February 2022 , Superconductor Science and Technology)

   Abstract One-dimensional c -axis-aligned BaZrO 3 (BZO) nanorods are regarded as strong one-dimensional artificial pinning centers (1D-APCs) in BZO-doped YaBa 2 Cu 3 O 7− x (BZO/YBCO) nanocomposite films. However, a microstructure analysis has revealed a defective, oxygen-deficient YBCO column around the BZO 1D-APCs due to the large lattice mismatch of ∼7.7% between the BZO (3a = 1.26 nm) and YBCO (c = 1.17 nm), which has been blamed for the reduced pinning efficiency of BZO 1D-APCs. Herein, we report a dynamic lattice enlargement approach on the tensile strained YBCO lattice during the BZO 1D-APCs growth to induce c -axis elongation of the YBCO lattice up to 1.26 nm near the BZO 1D-APC/YBCO interface via Ca/Cu substitution on single Cu-O planes of YBCO, which prevents the interfacial defect formation by reducing the BZO/YBCO lattice mismatch to ∼1.4%. Specifically, this is achieved by inserting thin Ca 0.3 Y 0.7 Ba 2 Cu 3 O 7− x (CaY-123) spacers as the Ca reservoir in 2–6 vol.% BZO/YBCO nanocomposite multilayer (ML) films. A defect-free, coherent BZO 1D-APC/YBCO interface is confirmed in transmission electron microscopy and elemental distribution analyses. Excitingly, up to five-fold enhancement of J c ( B ) at magnetic field Bmore »= 9.0 T// c -axis and 65 K–77 K was obtained in the ML samples as compared to their BZO/YBCO single-layer (SL) counterpart’s. This has led to a record high pinning force density F p together with significantly enhanced B max at which F p reaches its maximum value F p,max for BZO 1D-APCs at B // c -axis. At 65 K, the F p,max ∼158 GN m −3 and B max ∼ 8.0 T for the 6% BZO/YBCO ML samples represent a significant enhancement over F p,max ∼ 36.1 GN m −3 and B max ∼ 5.0 T for the 6% BZO/YBCO SL counterparts. This result not only illustrates the critical importance of a coherent BZO 1D-APC/YBCO interface in the pinning efficiency, but also provides a facile scheme to achieve such an interface to restore the pristine pinning efficiency of the BZO 1D-APCs.« less
2. In operando evidence of deoxygenation in ionic liquid gating of YBa ₂ Cu ₃ O _7-X

   https://doi.org/10.1073/pnas.1613006114  

   Perez-Muñoz, Ana M. ; Schio, Pedro ; Poloni, Roberta ; Fernandez-Martinez, Alejandro ; Rivera-Calzada, Alberto ; Cezar, Julio C. ; Salas-Colera, Eduardo ; Castro, German R. ; Kinney, Joseph ; Leon, Carlos ; et al ( January 2017 , Proceedings of the National Academy of Sciences)
3. Probing the effect of interface on vortex pinning efficiency of one-dimensional BaZrO ₃ and BaHfO ₃ artificial pinning centers in YBa ₂ Cu ₃ O _7-x thin films

   https://doi.org/10.1063/1.5050616  

   Gautam, Bibek ; Sebastian, Mary Ann ; Chen, Shihong ; Misra, Shikhar ; Huang, Jijie ; Javier Baca, F. ; Emergo, Rose ; Haugan, Timothy ; Xing, Zhongwen ; Wang, Haiyan ; et al ( November 2018 , Applied Physics Letters)
4. The angular range of effective pinning by one-dimensional artificial pinning centers in BaZrO ₃ /YBa ₂ Cu ₃ O _7-x nanocomposite films

   https://doi.org/10.1063/1.5097703  

   Ogunjimi, Victor ; Gautam, Bibek ; Sebastian, Mary Ann ; Haugan, Timothy ; Wu, Judy ( August 2019 , AIP Advances)
5. The effect of APC/YBCO interface on the angular range of effective pinning by one-dimensional artificial pinning centers in YBa ₂ Cu ₃ O _7-x nanocomposite films

   https://doi.org/10.1088/1757-899X/756/1/012025  

   Ogunjimi, V ; Gautam, B ; Sebastian, M.A. ; Haugan, T ; Wu, J ( March 2020 , IOP Conference Series: Materials Science and Engineering)