Magnetic-field penetration and structure of the mixed state in a superconductor with a multicomponent order parameter

Magnetic-field penetration in superconductors with a multicomponent order p arameter is discussed. Numerical simulation of the process is performed for a wide range of the external magnetic field and internal parameters of the system. It is found that the kinetic process of the vortex penetration reg ularly produces domain boundaries separating phases with different realizat ions of the equilibrium order parameter. As a result a new (mixed) vortex s tate can appear. It contains two different types of vortices connected to p airs and chains by the surface domain energy. The lattice formed by such vo rtices has a symmetry lower than hexagonal or tetragonal ones.