Inelastic neutron scattering studies of the paramagnetic phase in iron

Abstract

The paramegnetic phase of Fe(4%-Si) has been investigated by using polarized neutron scattering for temperatures ranging from the Curie temperature to $\sim 1.2T_c$ and for $q$'s ranging from 0.12 to 0.5 ${\mathrm{\AA }}^{-1\mathrm{}}$ at the 011 reciprocal lattice point. All measurements were put on an absolute intensity scale via simultaneously measured phonon cross sections. Our energy resolved measurements $S(\overrightarrow{Q},\omega )$ consisted of a broad energy distribution centered at zero energy transfer. However, no spin-wave-like peak was present in any of these constant-$Q$ scans which contradicts the large "spin-wave" peak reported at $q=0.47\mathrm{}$ ${\mathrm{\AA }}^{-1\mathrm{}}$ by Lynn. All recent theoretical models based upon this constant-$Q$ peak should be reexamined.