Magnetic property of the high-temperature superconductor GdBCO coated conductor

The basic electrical and magnetic superconducting properties of the commercially available High-Temperature Superconductor (HTS) GdBCO coated conductor (CC) specimens were investigated by using both a four-probe method and a magnetometer magnetization method with a physical property measurement system (PPMS). The H_irr(T) data in the region near the superconducting temperature T_c coincided very well with the power-law relation H_irr = H_irr(0)(1 − T/T_c)ⁿ. Similarly, the H_c2(T) data agreed well with the Bardeen, Cooper, and Schrieffer (BCS) type function H_c2 = H_c2(0)[1 − (T/T_c)^α]^β in the region near the T_c. On the other hand, the irreversible magnetic moment ∆m_irr was obtained by measuring the magnetic moment m(H). The Bean model was applied to obtain the related superconducting current density, J_c, of the GdBCO CC. The magnetic flux behavior was investigated from the relationship J_c ∝ H^−δ. At temperatures near T_c, the value of δ when the magnetic field was parallel to the ab-plane of the specimen was two times greater than the value of δ when it was parallel to the c-axis, but the difference between the δ values gradually decreased as the temperature was decreased.