The critical current density and irreversibility field of YBa2Cu3O7 films were resistively measured in fields up to 23T at 5 - 84K when the magnetic field B was applied parallel to the c-axis. The irreversibility field Bi at low temperature, which cannot be measured directly, was estimated using the temperature scaling law of the pinning force density. We found that the Bi values are proportional to (1-(T/Tc)2)1.4 at high temperature above 40K and then rapidly increase at low temperature below 40K The obtained Bi values at low temperature for B//c are very large, compared with that for other high-Tc superconductors. Moreover, the B, value estimated on the basis of the temperature scaling law of Fp exceeds at least 600T at 5.0K even for B//c.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering