Electrical resistance of YBa2Cu3Oz and Bi2(Sr,Ca)3Cu2Oz CVD films in the mixed state was investigated in magnetic field up to 25 T. The sheet resistance in the broad transition is expressed by R□=R0exp(-U0/kBT) on the low temperature side, and it is independent of the configuration of current with respect to the magnetic field. The activation energy U0 is larger in YBa2Cu3Oz films. The U0 value becomes smaller proportional to B-α with increasing field. Moreover, the resistance follows a power law of Bγ at constant temperature. The value of exponent γ is larger than unity and increases with decreasing temperature. These behaviors are discussed based on the flux creep models by Tinkham and by Dew-Hughes.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering