Nuclear Spin-Lattice Relaxation by Solitons in the Antiferromagnetic Chains (CH3)4NMnCl3

Abstract

The first evidence of nuclear spin-lattice relaxation (NSLR) by magnetic soliton fluctuations is presented. The NSLR rate ${T_1}^{-1\mathrm{}}$ of ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ in an enriched crystal of ${\left(\mathrm{C}{\mathrm{H}}_3\right)}_4$NMn${\mathrm{Cl}}_3$ is measured versus field ($20\lesssim H\lesssim 80$ kOe) and temperature ($2\lesssim T\lesssim 4.2$ K). At a given temperature an exponential divergence of ${T_1}^{-1\mathrm{}}$ is observed as a function of $H$. This drastic behavior is in complete agreement with the soliton model for planar antiferromagnetic chains.