Solitons in the antiferromagnetic XY chain

An important sampling Monte Carlo method is used to study the classical, antiferromagnetic, XY chain in a symmetry breaking uniform magnetic field. From equilibrium configurations the authors extract values for the bulk properties as well as explicit pictures showing individual spin directions. An analysis of the angles which the spin makes with the field shows clearly the presence of both " Pi -like" and "2 Pi -like" solitons. They also see two distinct types of " Pi -like" solitions which differ in their behavior as a function of field. The bulk properties are discussed in terms of both spin waves and soliton excitation.