DIRECT OBSERVATION OF CHARGE AND ORBITAL ORDERING IN LA0.5SR1.5MNO4

Charge ordering and orbital ordering in La0.5Sr1.5MnO4 have been inves tigated by using synchrotron x-ray diffraction. The alternating patter n of Mn3+/Mn4+ in real space is observed directly by making use of the ir anomalous dispersion. The first clear evidence of the orbital order ing of e(g) electrons on Mn3+ is also presented based on the measureme nts of ATS (anisotropy of the tensor of susceptibility) reflection nea r the Mn K-absorption edge, The present observations indicate that the charge ordering and orbital ordering occur simultaneously at a transi tion temperature higher than that of the spin ordering.