The magnetic moment in the parent phase of the iron-pnictide superconductors varies with composition even when the nominal charge of iron is unchanged. We propose the spin-lattice coupling due to the magneto-volume effect as the primary origin of this effect, and formulate a Landau theory to describe the dependence of the moment to the Fe-As layer separation. We then compare the superconductive critical temperature of doped iron pnictides to the local moment predicted by the theory, and suggest that the spin-phonon coupling may play a role in the superconductivity of this compound.
@article{arxiv.0908.4361,
title = {Spin-Phonon Coupling in Iron Pnictide Superconductors},
author = {T. Egami and B. V. Fine and D. J. Singh and D. Parshall and C. de la Cruz and P. Dai},
journal= {arXiv preprint arXiv:0908.4361},
year = {2015}
}