STRUCTURE OF VORTICES IN EXOTIC SUPERCONDUCTORS NEAR THE LOWER CRITICAL-FIELD

An analytical approach is proposed for describing the structure of the vortices in hexagonal and tetragonal exotic superconductors in fields close to H(ci). An arbitrary orientation of the magnetic field with respect to the crystal axes is considered. The structure of one-quantum singular vortices is studied, and the parameter range is found in which the singular solutions are unstable and nonsingular vortices are found to be energetically favored. The range of the angles between the directions of the magnetic field and crystal axes is found in which various types of vortices are realized. The angular dependences of the lower critical field H(ci), which are specific for superconductors with nontrivial pairing, are obtained.