CHARGED SKYRMIONS - A CONDENSATE OF SPIN EXCITONS IN A 2-DIMENSIONAL ELECTRON-GAS

The existence of topological defects, known as Skyrmions, within the s pin-exciton energy band of a two-dimensional (2D) electron gas under a strong magnetic field at filling factor nu = 1, is investigated withi n the Hartree-Fock (HF) approximation. Using the linear momentum repre sentation, developed previously for the description of magnetoexcitons in 2D electron systems, it is shown that the inhomogeneity created in the system by a charged Skyrmion can be described by a nonuniform rot ation of the spin-density operators in a condensate of spin excitons. In the limit when the spatial dependence of the rotation angles is ver y smooth on the magnetic length scale, it is found that the winding nu mber of a created Skyrmion is equal to the number of particles injecte d to, or removed from the system. The minimum HF energy level of a neu tral topological defect, i.e., a widely separated Skyrmion-anti-Skyrmi on pair with a unit winding number, is found to lay exactly in the mid dle of the spin-exciton energy band.