We use inelastic neutron scattering to show that the spin waves in the iron chalcogenide Fe1.05Te display novel dispersion clearly different from those in the related iron pnictide systems. By fitting the spin waves to a Heisenberg Hamiltonian, we extract magnetic exchange couplings that are dramatically different from both predictions by density functional calculations and measurements on the iron pnictide CaFe2As2. While the nearest-neighbor exchange couplings in CaFe2As2 and Fe1.05Te are quite different, their next-nearest-neighbor exchange couplings are similar. These results suggest that superconductivity in the pnictides and chalcogenides share a common magnetic origin that is intimately associated with the next-nearest-neighbor magnetic coupling between the irons.
@article{arxiv.1011.2930,
title = {Spin waves in the $(\pi,0)$ magnetically ordered iron chalcogenide Fe$_{1.05}$Te},
author = {O. J. Lipscombe and G. F. Chen and Chen Fang and T. G. Perring and D. L. Abernathy and A. D. Christianson and Takeshi Egami and Nanlin Wang and Jiangping Hu and Pengcheng Dai},
journal= {arXiv preprint arXiv:1011.2930},
year = {2011}
}