Strain Dependence of Superconducting Properties for GdBCO Coated Conductor in High Field Under Tensile Load

The strain dependence of T_c and I_c for the GdBCO coated conductor was measured at 77 and 4.2 K in magnetic fields. T_c decreased with increasing applied tensile strain. For the I_c measurements, the magnetic field was applied in the direction parallel to the c-axis (perpendicular to the tape surface). I_c in fields was degraded with increasing strain, and the strain dependence of I_c increased with increasing magnetic field. The ratio of the I_c degradation at 4.2 K was smaller than that at 77 K. These results mean that the T_c degradation is one of the reasons for I_c degradation at 77 K at least. Further, in order to understand the strain effect at 4.2 K, the internal strain of the GdBCO coated conductor under tensile strain was measured using synchrotron radiation. It was found that the strain behavior for the a-axis is different from that for the b-axis. This result suggests that the strain dependence of I_c for GdBCO coated conductors under external tensile strain is related with the T_c degradation behavior of the crystal.