Metallic stripes in oxygen doped La2CuO4

We have investigated the charge ordering in an oxygen doped La2CuO4 crystal by diffuse high-resolution x-ray diffraction using synchrotron radiation. The micro-strain epsilon in the CuO2 plane is close to the micro-strain Eo for the formation of static charge ordered phases. The crystal shows the co-existence of a first phase with an insulating crystal of charge strings and a second superconducting phase of "supestripes". The first insulating phase is due to charges at the critical doping 1/8 self trapped into a crystal of ordered strings of finite Length (similar to 60 Angstrom) and a commensurate period of 4 lattice units. The superconducting phase shows diffuse diffraction peaks with short coherence length due to fluctuations of stripes with an incommensurate period of about 4.8 unit cells and length longer than 500 Angstrom.