From manganites to cuprates: a comparative study of the local lattice instability

Recent studies have shown that structural instabilities play a vital role in segregation of charge carriers in the perovskites. We have used extended x- ray absorption fine structure (EXAFS) to investigate the instability 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) properties. Temperature dependent Cu K-edge EXAFS spectra on the LSCO and Mn Kedge on the LCMO systems are reported. The results show a similarity in the lattice instability of the two systems providing evidence for a similar phase segregation of localized and itinerant charge carriers in the two families of perovskite systems.