Magnons and Magnon-Phonon Interactions in Iron

First-principle studies of magnons and magnon-phonon interactions are carried out in bcc and fcc iron in the adiabatic approximation. It is shown that the phonons have a minor effect on magnons in bcc Fe and thus the lattice vibrations make a small contribution to the Curie temperature. fcc Fe is unstable against magnon excitations but the phonons seem to reduce this instability. The magnon-phonon interactions are analyzed in terms of the pair-exchange interaction variations as functions of the interatomic distances. The fcc results suggest that metastable fcc Fe in thin-film or nanostructure form should have interesting magnetic properties.