Enhancement Of Magnetic Vortex Pinning by APCs with Coherent BZO 1D-APC/YBCO Interface
type: CreativeWork
description: Strong magnetic vortex pinning is crucial for in-field high critical current density (Jc) sustaining applications. This pinning force can be realized by inserting artificial pinning centers (APCs) in high temperature superconductors (HTS) such as YBa2Cu3O7-x (YBCO). Unfortunately, a degraded APC/YBCO interface can limit the pinning force making high field/high Jc applications unfeasible. The effect of APC/YBCO interface on pinning is best exemplified by the difference in pinning force generated by c-axis (direction of film growth) aligned one-dimensional (1D) APC fabricated with BaZrO3 (BZO) on one hand and BaHfO3 (BHO) on the other. A considerably higher pinning force density (Fp) was observed on the BHO 1D-APCs, which was attributed to a less defective BHO/YBCO interface than the BZO/YBCO case. This defect-ridden BZO 1D-APC/YBCO interface has been blamed for the reduced pinning efficiency of BZO 1D-APCs and is consistent with a microstructure analysis that 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). In this thesis, I 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 reservoir spacers in BZO/YBCO nanocomposite films. A defect-free, coherent BZO 1D-APC/YBCO interface is confirmed in transmission electron microscopy and elemental distribution analyses. This has led to a record high pinning force density Fp illustrating the critical importance of a coherent BZO 1D-APC/YBCO interface in the pinning efficiency. The question of how the APC/YBCO interface affects angular range of the pinning…
abstract: Strong magnetic vortex pinning is crucial for in-field high critical current density (Jc) sustaining applications. This pinning force can be realized by inserting artificial pinning centers (APCs) in high temperature superconductors (HTS) such as YBa2Cu3O7-x (YBCO). Unfortunately, a degraded APC/YBCO interface can limit the pinning force making high field/high Jc applications unfeasible. The effect of APC/YBCO interface on pinning is best exemplified by the difference in pinning force generated by c-axis (direction of film growth) aligned one-dimensional (1D) APC fabricated with BaZrO3 (BZO) on one hand and BaHfO3 (BHO) on the other. A considerably higher pinning force density (Fp) was observed on the BHO 1D-APCs, which was attributed to a less defective BHO/YBCO interface than the BZO/YBCO case. This defect-ridden BZO 1D-APC/YBCO interface has been blamed for the reduced pinning efficiency of BZO 1D-APCs and is consistent with a microstructure analysis that 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). In this thesis, I 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 reservoir spacers in BZO/YBCO nanocomposite films. A defect-free, coherent BZO 1D-APC/YBCO interface is confirmed in transmission electron microscopy and elemental distribution analyses. This has led to a record high pinning force density Fp illustrating the critical importance of a coherent BZO 1D-APC/YBCO interface in the pinning efficiency. The question of how the APC/YBCO interface affects angular range of the pinning…
author: Ogunjimi, Victor
language: en
keywords: Condensed matter physics, Applied physics, Artificial Pinning Center, High Temperature Superconductors, Multilayer Structure, Thin Films, Vortex Pinning, YBCO
date published: 2022-12-31
date modified: 2026-07-24T02:46:52Z
provider: University of Kansas
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Kansas

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property ID: Handle
value: https://hdl.handle.net/1808/35755