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Charge and orbital ordering states of manganites have been observed directly by using synchrotron x-ray diffraction techniques. The alternating pattern of Mn3+ and Mn4+ in charge ordering state was elucidated by the anomalous dispersion method. The orbital ordering at Mn3+ sites is presented based on resonant x-ray scattering near Mn K-absorption edge. The scattering mechanism has been developed by considering the splitting of the Mn 4p levels due to the orbital ordering. The coupling among the charge, spin and orbital degrees of freedom is discussed.

A synchrotron radiation X-ray powder diffractometer for samples of very small amount has been developed to collect high-quality diffraction patterns under extreme conditions,i.e.at low temperature and/or high pressure. A new cylindrical imaging plate (CIP) is used as a detector, in addition to a conventional flat-type imaging plate (FIP). By using the CIP system, the diffraction data in a diffraction angle range −44 ≤ 2θ ≤ 122° are collected with a dynamic range of about 106. The alignment of the diffractometer, measurement and analysis are automatically operated by a workstation. A performance test shows that the CIP system has spatial resolution of about 0.07° with a dynamic range of 106. The diffraction pattern of a standard sample of Si measured by the CIP system has high quality; the refinement of the structure reachesRw= 3.68% even in the case of a small amount of sample (about 2 µg) and a short exposure time (60 s). Examples of experiments at low temperatures under ambient and high pressures are also presented.

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