Instability in the magnetic field penetration in type II superconductors

• TDGL is used to study the magnetic field penetration in type II superconductors.
• Instability process is found during the magnetic field penetration.
• Vortices along the front of the normal region escape to superconducting region.
• We explain the extra-gain of kinetic energy by vortices along the borderline.

Under the view of the time-dependent Ginzburg–Landau theory we have investigated the penetration of the magnetic field in the type II superconductors. We show that the single vortices, situated along the borderline, between the normal region channel and the superconducting region, can escape to regions still empty of vortices. We show that the origin of this process is the repulsive nature of vortex–vortex interaction, in addition to the non-homogeneous distribution of the vortices along the normal region channel. Using London theory we explain the extra gain of kinetic energy by the vortices situated along this borderline.