Effect of an external magnetic field and a trapped magnetic flux on the current-voltage characteristics of a granular high-temperature superconductor YBa2Cu3O7-delta

摘要

A comparative study of the current-voltage characteristics of the high-temperature ceramic superconductor YBa2Cu3O-6.95 at T = 77.3 K is performed over wide ranges of external magnetic fields H-ext and "treatment" fields H-treat. It is found that the field dependences of the parameters a and j(c) involved in the exponential equation E = a(j - j (c))(v) describing the current-voltage characteristics depend substantially on the method used for applying the magnetic field, whereas the exponent v similar to 2 depends on neither the method of application nor on the magnetic field strength. The field dependence of the trapped magnetic field H-trap is determined.