  The chiral spin textures of a two-dimensional (2D) triangular system, where
both antiferromagnetic (AF) Heisenberg exchange and chiral Dzyaloshinsky-Moriya
interactions co-exist, are investigated numerically with an optimized quantum
Monte Carlo method based on mean-field theory. We find that: helical,
skyrmionic and vortical AF crystals can be formed when an external magnetic
field is applied perpendicular to the 2D monolayer; the sizes of these
skyrmions and vortices change abruptly at several critical points of the
external magnetic field; each of these AF crystals can be decomposed into three
periodical ferromagnetic (FM) sublattices. The quantum ingredient implemented
into the theoeretical framework helps to track the existence of AF skyrmion
lattices down to low temperatures.
