Spin Waves and the Order-Disorder Transition in Chromium

The inelastic magnetic scattering of neutrons has been studied in Cr and ${\mathrm{Cr}}_{0.95}$-${\mathrm{Mn}}_{0.05}$ both below and above the Néel temperature. The temperature dependence of the spin-wave velocity in the alloy has been measured below $T_{\mathrm{N}}$. The scattering above $T_{\mathrm{N}}$ may also be interpreted in terms of spin-wavelike excitations, which persist far into the paramagnetic phase.