Diffusive spin dynamics in lanthanomanganites with colossal magnetoresistance behaviour

Neutron scattering has been used to study the magnetic correlations and the spin dynamics in the ferromagnetic lanthanum-manganite La0.75Ca0.25MnO3 ab ove and below the Curie temperature. This material is known to exhibit colo ssal magnetoresistence behaviour, and its origin is strictly correlated to electron-lattice coupling. Quasielastic neutron scattering measurements sho w the presence of a diffusive central peak in the low-e region (up to about 0.5 Angstrom (-1)) that persists above T-C. The correlation length deduced from this contribution is about 8 Angstrom, the diffusion coefficient deri ved from the Q-dependence of the quasielastic broadening agrees with that e xpected for electron diffusion 'assisted' by lattice distortions. (C) 2001 Elsevier Science B.V, All rights reserved.