Theoretical and Experimental Spin-Relaxation Functions in Paramagnetic RbMnF3

Neutron-scattering measurements of the spectral density ${\chi }_T\left(\overrightarrow{\mathrm{q}}\right)F(\overrightarrow{\mathrm{q}},\omega )$ of the spin-relaxation function in the Heisenberg paramagnet RbMn${\mathrm{F}}_3$ are presented for the temperature range $T_{\mathrm{N}} \mathrm{to} 3.55T_{\mathrm{N}}$. Spectral densities, utilizing shape functions $F(\overrightarrow{\mathrm{q}},\omega )$ determined by Reiter, are compared directly with experiment on an absolute basis. Some interesting properties of ${\chi }_T\left(\overrightarrow{\mathrm{q}}\right)$ are reported and comparison of measured values is made with recent calculations by Collins.