Exactly solvable model of flux creep in high-[ital T][sub [ital c]] superconductors

An exactly solvable model of flux creep in high-[ital T][sub [ital c]] superconductors within the framework of both thermally activated and quantum-tunneling flux-creep theory is presented in this paper. The activation energy and crossover temperature between activated creep and quantum tunneling are explicitly expressed for an elastic flux line in a typical weakly periodical or quartic pinning potential involving a viscous medium. The exact analytic expression of magnetic relaxation rate is derived for the full parameter range. These expressions are somewhat better because several superconducting mechanism-sensitive parameters have been included. The present results are in reasonable agreement with the experimental data obtained in high-[ital T][sub [ital c]] superconductors.