Paramagnetic and Glass States of a YBCO Film Containing Nanorods at Low Magnetic Fields

The magnetic properties of YBa2Cu3O7-x (YBCO) multilayered film containing BaHfO3 (BHO) nanorods at zero and small fields have been investigated. The dc magnetization and the ac susceptibility were measured with a SQUID magnetometer. The paramagnetic magnetization is shown after the field-cool-warming below the transition temperature Tc = 87 K. The nonlinear susceptibility had a large peak around Tc, which reflects a glass-transition. An aging effect occured in the relaxation of zero-field-cooled magnetization below the Tc. Paramagnetic behavior and magnetic-glass properties were observed in the YBCO multilayered film containing BHO nanorods. The results suggest that the YBCO multilayered film is a novel magnetic-glass system at low fields.30th International Symposium on Superconductivity (ISS2017), 13–15 December 2017, Tokyo, Japa

Control of Vortex Pinning in YBCO Thin Films by Incorporating APCs Through Surface Modified Target Approach

The transport of electrical currents in superconductors with much higher efficiency and without any dissipation is considered as the “energy superhighway.” After the discovery of YBa2Cu3O7-δ (YBCO), a high temperature superconductor (HTS), the prospect of using superconducting materials in practical technological applications became very prominent. With much higher Tc (～ 92 K) than conventional low temperature superconductors (LTS), YBCO was considered very promising due to cheaper cooling requirements. The evolution of critical current density (Jc), however, took long time for the material to become useful in practical applications. This was achieved through continuous modification of the processing parameters, deposition of highly oriented thin films on single crystal and buffered metallic substrates and use of artificial pinning centers (APCs) for strong pinning of quantized magnetic vortices. Pulsed laser deposition (PLD) technique is one of the most common and highly efficient techniques for depositing highly oriented YBCO thin films on single crystal and buffered metallic substrates. Using PLD technique, APCs are incorporated into YBCO thin films by many methods which include premixed target method, alternating target method and surface modified target method. In this chapter, the use of surface modified target method to introduce different kinds of APCs into YBCO thin films is presented. These APCs are effective in improving the vortex pinning properties of YBCO thin films for different range of applied magnetic field and its orientation depending upon their geometry and density.Chapter