Synchrotron x-ray diffraction study of a charge stripe order in 1/8-doped La_1.875Ba_0.125-xSr_xCuO₄

Lattice distortions associated with charge stripe order in 1/8 hole-doped La_1.875Ba_0.125-xSr_xCuO₄ are studied using synchrotron x-ray diffraction for x = 0.05 and x = 0.075. The propagation wave-vector and charge order correlation lengths are determined with a high accuracy, revealing that the oblique charge stripes in orthorhombic x = 0.075 crystal are more disordered than the aligned stripes in tetragonal x = 0.05 crystal. The twofold periodicity of lattice modulations along the c axis is explained by long-range Coulomb interactions between holes on neighboring CuO₂ planes.