Solitons in the paramagnetic and partially disordered phases of CsCoCl3.

Abstract

We present a detailed quantitative experimental analysis of the soliton regime in a one-dimensional (1D) quantum spin system. The experiments were performed on the 1D antiferromagnet ${\mathrm{CsCoCl}}_{3}$. As well as soliton fluctuations, a 1D antiferromagnetic mode was observed in both the paramagnetic (Tg${T}_{N1}$\ensuremath{\simeq}21 K) and the partially disordered (T${T}_{N1}$) phases. This result proves that, below ${T}_{N1}$, one third of the chains remains in a paramagnetic state with fluctuations governed by solitons. In a semiphenomenological model the collisions between solitons are explicitly taken into account in our description, yielding good agreement between theory and experiment over the whole temperature range.