Polarization-dependent resonant-x-ray diffraction in charge- and orbital-ordering phase ofNd1/2Sr1/2MnO3

A study of resonant-x-ray scattering in a charge-ordered perovskite manganese oxide ${\mathrm{Nd}}_{1/2}{\mathrm{Sr}}_{1/2}{\mathrm{MnO}}_3$ was performed. Dipole-resonant superlattice reflections originating from the orderings of the charge and orbital with $Q_{\mathrm{charge}}=(0,1,0)\mathrm{}$ and $Q_{\mathrm{orbital}}=(0,1/2,0)\mathrm{}$ in the $\mathrm{Pbnm}$ 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 ${(d}_{{3x}^2-r^2}{/d}_{{3y}^2-r^2})$ or ${(d}_{x^2-z^2}{/d}_{y^2-z^2}).\mathrm{}$