Exchange Narrowing in One-Dimensional Systems

Magnetic relaxation in one-dimensional exchange-coupled ${\left(\mathrm{C}{\mathrm{H}}_3\right)}_4$NMn${\mathrm{Cl}}_3$ is found to be dramatically different than it is in three-dimensional exchange-narrowed paramagnets. A theory which accounts properly for the special long-time persistence of spin-correlation functions in one dimension is shown to explain the observed behavior.