Spin wave dispersion softening in the ferromagnetic Kondo lattice model for manganites
arXiv:cond-mat/0011464 · doi:10.1016/S0375-9601(01)00321-8
Abstract
Spin dynamics is calculated in the ferromagnetic (FM) state of the generalized Kondo lattice model taking into account strong on-site correlations between e_g electrons and antiferromagnetic (AFM) exchange among t_{2g} spins. Our study suggests that competing FM double-exchange and AFM super-exchange interaction lead to a rather nontrivial spin-wave spectrum. While spin excitations have a conventional Dq^2 spectrum in the long-wavelength limit, there is a strong deviation from the spin-wave spectrum of the isotropic Heisenberg model close to the zone boundary. The relevance of our results to the experimental data are discussed.
6 RevTex pages, 3 embedded PostScript figures