Q-Dependence of the Soliton Response in CsNiF₃ at T = 10K and H = 5 kg

Abstract

Recently the first direct experimental evidence of solitons in the one-dimensional (I-D) ferromagnetic chain system CsNiF₃ with easy plane anisotropy was reported by Kjems and Steiner [1]. They observed a quasi-elastic component in the dynamic structure factor which was interpreted within the theoretical framework developed by Mikeska [4] for a I-D XY-ferromagnet in an applied field. Mikeska had showed that the spin dynamics of such systems are described by the Sine-Gordon equation and this enabled him to predict explicitly the characteristic temperature and field dependence of the scattering due to non-linear modes -such as kinks or solitons. The predictions agreed very well with the results of the first neutron scattering experiment [1]. Another important prediction of the theory is the wavevector dependence of the energy width and of the integrated quasielastic intensity. This has been measured in a subsequent experiment and the results are reported here.