Neutron scattering results are presented for spin-wave excitations of three ferromagnetic metallic A1−xAx′MnO3 manganites (where A and A′ are rare- and alkaline-earth ions), which when combined with previous work elucidate systematics of the interactions as a function of carrier concentration x, on-site disorder, and strength of the lattice distortion. The long wavelength spin dynamics show only a very weak dependence across the series. The ratio of fourth to first neighbor exchange (J4/J1) that controls the zone boundary magnon softening changes systematically with x, but does not depend on the other parameters. None of the prevailing models can account for these behaviors.
@article{arxiv.cond-mat/0512368,
title = {Evolution of spin-wave excitations in ferromagnetic metallic manganites},
author = {F. Ye and Pengcheng Dai and J. A. Fernandez-Baca and Hao Sha and J. W. Lynn and H. Kawano-Furukawa and Y. Tomioka and Y. Tokura and Jiandi Zhang},
journal= {arXiv preprint arXiv:cond-mat/0512368},
year = {2007}
}