Exact treatments of activation energy, quantum tunneling and flux-creep rate in high-Tc superconductors

Within the framework of both thermally activated and quantum-tunneling flux-creep models, an exact treatment of the activation energy, the quantum tunneling and the flux-creep rate in high-Tc superconductors is presented. For a typical quartic pinning potential in a viscous medium, the parameter-dependent activation energy and quantum tunneling of the system are studied in detail. Reliable determinations of the magnetic relaxation rate for a given strong type-II high-Tc superconductor will enable a check of the validity of the theoretical results. (orig.)