Nonlinear excitations in a two-dimensional hard-core charged Bose gas with an effective intersite repulsion

The effect of intersite repulsion on the features of nonlinear topological excitations is studied for a two-dimensional hard-core Bose gas on a lattice within the continuum approximation. It is shown that the excitations are subdivided into two classes and may be associated with the well-known ground-state phases via the behavior at boundaries. Among the excitations having counterparts in magnets such as skyrmions, out-of-plane vortices, ``easy axis,'' and Takeno-Homma solitons there is a new type of nonlinear excitations: excitations of ``mixed''-state type.