Inelastic neutron scattering measurements demonstrate that the magnetic interactions in antiferromagnetic LaFeAsO are two-dimensional. Spin wave velocities within the Fe layer and the magnitude of the spin gap are similar to the \textit{A}Fe2As2 based materials. However, the ratio of interlayer and intralayer exchange is found to be less than ∼10−4 in LaFeAsO, very similar to the cuprates, and ∼ 100 times smaller than that found in \textit{A}Fe2As2 compounds. The results suggest that the effective dimensionality of the magnetic system is highly variable in the parent compounds of the iron arsenides and weak 3-D interactions may limit the maximum attainable superconducting Tc.
@article{arxiv.1303.4033,
title = {Two-dimensional magnetic interactions in LaFeAsO},
author = {M. Ramazanoglu and 1 and 2 J. Lamsal and 1 and 2 G. S. Tucker and 1 and 2 J. -Q. Yan and 3 S. Calder and 3 T. Guidi and 4 T. Perring and 4 R. W. McCallum and 1 and 2 T. A. Lograsso and 1 and 2 A. Kreyssig and 1 and 2 A. I. Goldman and 1 and 2 and R. J. McQueeney1 and 2 1 and 2 and 3 and 4},
journal= {arXiv preprint arXiv:1303.4033},
year = {2015}
}