Magnetic characteristics of superconducting REBa2Cu3O7-8 crystals

• Main Author: Roleda, Lydia Soberano
• Format: text
• Language: English
• Published: Animo Repository 2002
• Subjects: Superconductors > Magnetic properties; Flux pinning; Superconductivity; Crystals; Physics
• Online Access: https://animorepository.dlsu.edu.ph/etd_doctoral/896
• Institution: De La Salle University

A deeper understanding of high-Tc superconductivity can be provided by an investigation of the intrinsic properties of superconductors. With this motivation, the magnetic characteristics of superconducting REBa2Cu307-8 (RE, or rare earth= yttrium, neodymium) crystals is the focus of this thesis. High purity, high quality single YBa2Cu307-8 (YBCO) crystals were grown via a flux method. The irreversibility lines, pinning energies and critical current densities were determined using ac susceptibility and relaxation measurements. The effect of the presence of twins in these crystals was also studied. Melt processed intergrowth Nd1/2Y1/2Ba2Cu307-8 (Nd/Y)BCO) crystals (with 3 percent (Nd/Y)2BaCu05) were also fabricated for comparison of the effect of doping on the magnetic properties of high Tc superconductors. The empirical relation Hdc=K was obtained for the irreversibility lines (IL) of these clean crystals accounting for the simultaneous dependence of IL on the ac field amplitude and frequency.