Single-kink dynamics in an easy-plane classical antiferromagnetic chain

The authors present an ansatz for kink excitations in an easy-plane classical antiferromagnetic chain with a magnetic field in the easy plane. The utility of the ansatz is that it presents the in-plane (XY) and out-of-plane (YZ) kinks as belonging to one continuously connected energy dispersion curve. Linear stability analysis applied to YZ kinks shows that there is a velocity-dependent critical field necessary for stability. The authors also present a set of results of a numerical integration of the equations of motion which verifies the YZ kink stability regimes, as well as showing that XY kinks are stable over a wide range of fields and velocities.