FROM MANGANITES TO CUPRATES - A COMPARATIVE-STUDY OF THE LOCAL LATTICE INSTABILITY

Recent studies have shown that structural instabilities play a vital r ole in segregation of charge carriers in the perovskites, We have used extended x-ray absorption fine structure (EXAFS) to investigate the i nstability of the CuO6 octahedra of the La1.85Sr0.15CuO4 (LSCO) system showing high Tc superconductivity and the MnO6 octhahedra of the La0. 75Ca0.25MnO3 (LCMO) system showing GMR (giant-magneto resistance) prop erties, Temperature dependent Cu K-edge EXAFS spectra on the LSCO and Mn Kedge on the LCMO systems are reported. The results show a similari ty in the lattice instability of the two systems providing evidence fo r a similar phase segregation of localized and itinerant charge carrie rs in the two families of perovskite systems.