Magnon softening and damping in the ferromagnetic manganites due to orbital correlations

Abstract

We present a theory for spin excitations in ferromagnetic metallic manganites and demonstrate that orbital fluctuations have strong effects on the magnon dynamics in the case these compounds are close to a transition to an orbital ordered state. In particular we show that the scattering of the spin excitations by low-lying orbital modes with cubic symmetry causes both the magnon softening and damping observed experimentally.

2 pages, 2 figures, SCES2003 Roma, to appear in J. Mag. Magn. Mat

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