Magnetic excitation in non-stoichiometric wustite (Fe1-xo)

Abstract

Inelastic neutron scattering measurements have been performed on monocrystalline samples of antiferromagnetic iron monoxide (Fe1-xO) for several compositions (x = 0.056, 0.070 and 0.072). The magnetic excitations up to 8THz have been investigated in order to find with precision the stoichiometry dependence of the spin dynamics. The experimental results have been analysed using a Green function formalism taking into account the spin-orbit interaction, the magnetoelastic coupling and the exchange interactions extending to the second neighbours. The main effect of the stoichiometry on the spin wave branch and the first excited level is a broadening of the magnon lineshapes. Nevertheless, in the case of x = 0.056, several peculiar excitations have been found which are probably related to the defect structure and long-range ordering. This ordering has been corroborated by the observation of elastic scattering corresponding to a modulated magnetic and nuclear structure. © 1985, IOP Publishing Ltd.