One dimensional ordering of doping oxygen in HgBa2Cuo4+δHgBa2Cuo4+δ superconductors evidenced by X-ray diffuse scattering

X-ray diffuse scattering experiments on single CuO2 layer Hg high Tc superconductors (HgBa2CuO4+δHgBa2CuO4+δ) near optimal doping level have revealed that the doping oxygen atoms of this system form very long and isolated chains (extending over 75 unit cells in average) in both tetragonal directions, with correlated transverse and longitudinal displacements of at least the nearby pairs of mercury atoms and copper atoms from two coupled CuO2 layers. Signs of incommensurate periodic lattice distortion have been also observed.