The superconducting properties of a high-temperature superconducting GdBCO-coated conductor

The basic magnetic properties of commercially available High-Tc Superconductor (HTS) GdBCO-coated conductor (GdBCO-CCs) were investigated by using physical property measurement system-vibrating sample magnetometer (PPMS-VSM). From the zero-field-cooled (ZFC) m(T) curve, the Tc was found to be ∼93 K. After removing the background m(H) data, we obtained both the net m(H) data and the ∆mirr. The Hirr(T) coincided very well with the power-law relation Hirr = Hirr(0)(1 − T/Tc)ⁿ with n ^∼= 1.19. The magnetic flux behavior was investigated by using the δ values in the relationship Jc ∝ ∆mirr ∝ H^−δ. A δ ≈ 0 region denoting an independent magnetic flux pinning effect, a δ ≈ 0.6 ∼ 1.2 region representing a collective flux pinning effect due to the interaction, and a δ ≫ 2 region representing freely moving magnetic fluxes caused by the Lorentz force were observed. The boundary line between δ ≈ 0 and δ ≈ 0.6 ∼ 1.2 is denoted by a H1, and the one between δ ≈ 0.6 ∼ 1.2 and δ ≫ 2 is denoted by a H2. The δ(T) was obtained in the region of H1 < H < H2. As the temperature was decreased, the δ value gradually decreased.