Applied Physics Research; Vol. 10, No. 6; 2018 ISSN 1916-9639 E-ISSN 1916-9647 Published by Canadian Center of Science and Education 109 Enhancement of Critical Current Density of Yttrium Barium Copper Oxide Thin Films by Introducing Nano dimensional Cerium Oxide Defects Tochukwu Emeakaroha 1 , Floyd James 1 & Abebe Kebede 1 1 Department of Physics and Astronomy North Carolina Agricultural and Technical State University, Greensboro, North Carolina, 27401, USA Correspondence: Tochukwu Emeakaroha, Department of Physics and Astronomy North Carolina Agricultural and Technical State University, Greensboro, North Carolina, 27401, USA. E-mail: tmemeaka@aggies.ncat.edu Received: October 14, 2018 Accepted: November 2, 2018 Online Published: November 30, 2018 doi:10.5539/apr.v10n6p109 URL: https://doi.org/10.5539/apr.v10n6p109 Abstract The critical current density,  ௖ has been the most important parameter used in the design and engineering of effective devices which is one of the implementation of high temperature superconductors (HTSC). In this work, an effort has been made to further improve the critical current density of YBa 2 Cu 3 O 7-x (YBCO) thin films by preventing the magnetic flux line lattice against the Lorentz force by pinning it in place with the aid of nano-dimensional defects. These defects were generated by distributing nano sized CeO 2 islands after YBCO layer was created on LaAlO 3 substrates perpendicular to the film using pulsed laser deposition (PLD) technique. Three samples with buffer layers of CeO 2 were prepared. CeO 2 with 50 pulses, 100 pulses and 150 pulses, after each 1000 pulses of YBCO were prepared five layers for each of the samples. The structural characterization of YBCO/CeO 2 and YBCO pristine films were carried out using x-ray diffraction (XRD) and scanning electron microscopy (SEM). Superconducting proprieties were measured using a vibrating sample magnetometer (VSM).  ௖ for the pure YBCO and the YBCO/CeO 2 films were calculated from magnetization (M) versus Field (H) loops using Bean’s model.  ௖ for the 50 pulses of YBCO/CeO 2 films was found to be increased slightly by an order of magnitude of about 40% with respect to those of YBCO films without the nano dimensional defects. Keywords: high temperature superconductivity, thin films, YBCO, CeO 2 , critical current density. 1. Introduction. YBa 2 Cu 3 O 7− x (YBCO) film has attracted a lot of attention in electrical power applications due to its high critical transition temperature T c (>90 K) and critical current density J c (>1 MA cm −2 ) (Lei, Zhao, Xu, Wu, & Chen, 2011; Haugan, Barnes, Brunke, Manrtense & Murphy, 2003). The growth of YBa 2 Cu 3 O 7-x (YBCO) thin films is of great interest for superconducting applications because of its power transmission magnetic shielding, low phase noise oscillators, magnetic resonance imaging receiver coils (Chen et al., 2016; Matsuunotoet al.,, 2004; Rejith, Vidya &Thomas, 2015; Zhao, Ito & Goto, 2014). Fine precipitates, dislocations, grain boundaries and vacancies are many kinds of crystalline defects, being considered as pinning centers (Zhao, Ito & Goto, 2014; Kujur, Sahoo, Panda, Asokan & Behera, 2013). The pinning centers depend on size, shape and concentration to achieve effective defects. The critical current density is highly influenced by flux lattice motion due to thermal fluctuations and Lorentz force due to applied magnetic fields. To maintain the necessary levels of high J c in high applied magnetic fields we need high spatial densities or naturally occurring growth defect to suppress the thermal fluctuations to stop the vortex mobility by pining them. Although nanodots of CeO 2 have been shown to induce additional flux pinning, this has always been due to strain in the YBCO lattice because of these inclusions. Such strain however, could have detrimental effect on the YBCO. Aside from the thickness dependence of J c , there is also a limitation placed on the thickness at which such films could be grown (Uzun & Avci, 2014; Zhao, Iton & Goto, 2014; Sueyoshi, Kotaki, Fujiyoshi, Mitsugi, Ikegami & Ishikawa, 2013). (Huang, Li, Wang, Qi, Sebastain, Haugan, &Wang, 2017), reported the enhanced flux pinning properties of YBCO thin films with various pinning landscapes a magnetic nanocomposite of La 0.7 Sr 0.3 MnO 3 (LSMO))x (CeO 2 ) 1-x was incorporated into YBCO as either a cap layer or a buffer layer but the defect pinning and magnetic pinning are introduced in the systems giving the J c at 77K to be around 4.66MA/cm 2 (Xu et al., 2012), reported the influence