Spatial cross-over of polarons across the CMR transition in La0.75Ca0.25MnO3 system

We have measured high resolution Mn K-edge x-ray absorption near edge struc ture (XANES) and extended x-ray absorption fine structure (EXAFS) to invest igate the local atomic displacements in the MnO6 octahedra and their import ance to the colossal magnetoresistance in the La0.75Ca0.25MnO3 system. A co mbined analysis of the XANES and EXAFS shows that the colossal-magneto resi stance (CMR) transition is characterized by a transition from a phase of de localized intermediate polarons to a phase showing coexistence of the inter mediate and small polarons accompanied by the opening of a gap at EF due to Jahn Teller splitting of eg orbitals.