Stability of a Vortex near the Surface of Ferromagnetic Superconductors

抄録

Near the surface of ferromagnetic superconductors, the free energy difference between the single vortex state and the no vortex state is calculated as a function of the distance between the vortex and the surface for various values of temperature T and external magnetic field H₀. It is shown that the vortex is bound near the surface at T<T_o under H₀ higher than a critical value, where T_o is the characteristic temperature below which the external magnetic field penetrates into the crystal in an oscillatory fashion. The interaction between the vortex and the penetrating magnetic field plays an important role in the stability of the vortex near the surface. A possibility of the self-induced vortex state near the surface is predicted.