Antiferromagnetic domain walls

Antiferromagnetic domain walls are shown to exhibit a nonvanishing total magnetic moment. This result is established numerically for a discrete spin system, as well as analytically within a suitable continuum approximation that leads to the nonlinear {σ} model extended to include anisotropy. The moment is due to certain parity-breaking terms that are implicit in arguments pertaining to the Haldane gap but have been missing in earlier treatments of domain walls. In this paper we present a study of both static and dynamical properties of domain walls in antiferromagnets with an easy-axis anisotropy, but some of the results should prove relevant also for weak ferromagnets.