A neutron investigation of the soliton regime in the one-dimensional planar antiferromagnet (CD3)4NMnCl3

Abstract

The authors present a detailed quantitative experimental analysis of the soliton regime in a magnetic chain compound. The experiments described were performed on the one-dimensional antiferromagnet TMMC ((CD₃)₄NMnCl₃) which is known to be a planar system below 5K. By applying a magnetic field in the plane perpendicular to the chain axis one can create solitons which correspond to the solutions of a sine-Gordon equation. An intense quasi-elastic (central) peak is observed, the width of which results from the flipping of the spins associated with the sublattices each time a soliton passes by. This feature is characteristic of antiferromagnetic chains. Together with a detailed neutron analysis it allows the authors to develop a quantitative study of the soliton regime. This is made by varying both the magnetic field (H approximately=0-50 kOe) and the temperature (T approximately=1.5-5K). A characteristic exponential dependence as a function of H/T is established for both the energy and wavevector widths of the central peak. The soliton energy is determined with very good accuracy and it is shown that quantum corrections are important in TMMC.