Periodic hole structure in a spin-chain ladder material SrCuO

Fukuda, Tatsuo  ; Mizuki, Junichiro; Matsuda, Masaaki

High-energy synchrotron X-ray diffraction measurements were carried out on a single crystal of SrCuO, and we found that the lattice distortion has not but times the periodicity of the chain structure along (II chain axis) direction at low temperature. These satellite peaks decreased in intensity with increasing temperature. These observations were interpreted properly in terms of a hole ordering model involving the dimerized state of two Cu ions and a Cu ion on a Zhang-Rice singlet site in the CuO chains. These features were clearly observed by using high-energy X-rays (53.789 keV), while the superlattice peak intensity varied drastically with very little sample surface treatment in the case of low-energy X-ray experiments (15.498 keV).