Effects of local lattice disorder on the superconductivity studied by XAFS

Abstract

The variation of local lattice displacements of the in-plane Cu-O bond upon Cu-site impurity doping in La2-xSrxCuO4 superconductor is investigated by Cu K-edge EXAFS studies. In Mn doping case, the analysis of the temperature dependence of Debye-Waller factor indicates that the local lattice displacements of the in-plane Cu-O bond exhibits similar behavior in all La1.875-1.5xSr0.125+1.5xCu 1-xMnxO4 (0≤x≤0.15) samples. This may reflect that the doping of Mn does not alter the local lattice environments in the CuO2 plane and thus the Mn impurity does not destroy the superconducting transition in a similar way with other ionic doping cases. The local lattice displacements at room temperature upon ionic doping are compared, which indicates that Fe doping leads to largest local displacements while Ni doping is intermediate. The possible interplay between the local lattice displacements and the normal-state resistivity is compared. These results indicate that the local lattice displacements largely affect the superconducting properties in La2-xSrxCuO4 superconductor. © 2008 IOP Publishing Ltd.