Inhomogeneity in the spin channel of ferromagnetic CMR manganites

Colossal magnetoresistance manganites are archetypes in which to study the strong coupling between spin, charge and lattice degrees of freedom in materials. We present nation spin-lattice relaxation data in ferromagnetic (FM) ground state materials from the manganite series La1-xCaxMnO3 and La1-x-yPryCaxMnO3. These measurements reveal several characteristic relaxation modes arising from the strong spin-charge-lattice interactions. We also present results from neutron-spin-echo spectroscopy, which directly measures the spin-spin correlation function in a time domain comparable to muSR. A qualitative model for the FM transition in the manganites involving microscopic phase separation is suggested by these data. (C) 2002 Elsevier Science B.V. All rights reserved.