Neutron scattering study of the magnetic excitations in ferromagnetic iron at high energy transfers

Abstract

We have measured the spin-wave spectrum of iron by neutron inelastic scattering using the Low-Resolution Medium-Energy Chopper Spectrometer at the Intense Pulsed Neutron Source (IPNS) of the Argonne National Laboratory. Interest focuses on the magnetic excitations at high energy transfers where the spin-wave dispersion relation has not previously been determined. In measurements performed at 10 K using a 23-g single crystal of pure iron, we observed magnetic scattering around the (110) reciprocal lattice point with spin-wave energies from 40 to 160 meV. The spin waves over the entire range of energy are found to be consistent with an isotropic spin-wave dispersion relation. With the present experimental sensitivity we were unable to observe any band structure effects such as Stoner excitations or optical magnons in this range of wave vector and energy.