Polarization-dependent resonant-x-ray diffraction in charge- and orbital-ordering phase of Nd1/2Sr1/2MnO3

A study of resonant-x-ray scattering in a charge-ordered perovskite manganese oxide Nd1/2Sr1/2MnO3 was performed. Dipole-resonant superlattice reflections originating from the orderings of the charge and orbital with Q(charge)=(0,1,0) and Q(orbital)=(0,1/2,0) in the Pbnm setting were observed. Sudden change in the intensity of the superlattice scattering at the transition temperature indicated a strong first-order phase transition. Characteristic dependence on the x-ray polarization was observed not only for orbital-order superlattice scattering but also for charge-order scattering. It should be closely related to the orbital-ordering type (d(3x2-r2)/d(3y2-r2)) or (d(x2-z2)/d(y2-z2)).