Magnetic vortices in small ferromagnetic particles with the strong dipolar interaction

The ground state of cylindrical magnetic samples of different sizes at nonzero applied magnetic field is studied theoretically taking into account the exchange and dipole-dipole interactions at an arbitrary ratio of coupling constants. In addition to the weakly inhomogeneous and standard vortex states well known for the case of the weak dipole-dipole interaction, the vortex states with the complicated structure of the vortex core have been found. The state diagram for these particles has been constructed and analyzed in terms of scaling consideration.