Macroscopic Quantum Creep in the Mixed State of High-κ Superconductors

The transition process from quasi-homogeneous mixed state to the state with macroscopic roton-like excitation is described. The transition occurs due to a weak external current. The contribution of this process to the quantum flux creep is calculated. The obtained relaxation rate depends strongly on the current density, the magnetic induction and material parameters. Particularly strong is the dependence of the relaxation rate on London penetration depth. The crossover temperature separating the macroscopic quantum and thermal creep regimes is calculated.