Local lattice structure in Mn-doped La2-x Srx Cu O4 studied by Cu and Mn K -edge XAFS

The local lattice structures in Mn-doped La2-x Srx Cu O4 are investigated by Cu K -edge and Mn K -edge x-ray-absorption near-edge structure and extended x-ray-absorption fine structure from 10 to 300 K. The results confirm that the doped Mn ions are located at the Cu site of La2-x Srx Cu O4 phase and the impurity phases, such as La1-x Srx Mn O3, are not presented in the samples. It is found that the local lattice structures of Cu are not affected by Mn impurities and the local lattice environments of Mn are similar to those of Cu. We consider that the Mn impurities only break the Cu-O p-d hybridization locally, while the local lattice environments and the superconductivity in the regions away from the impurities remain untouched. This result implicates that local lattice inhomogeneity plays an important role in the mechanism of high-temperature superconductivity. © 2007 The American Physical Society.