Interference between Thomson Scattering and Resonant Scattering in X-Ray Diffraction from CeB₆

Abstract

We reexamine the mechanism of the x-ray diffraction process by including the Thomson scattering (TS) term in addition to the resonant x-ray scattering (RXS) term previously evaluated by the present authors near the Ce L_III absorption edge in the antiferroquadrupole (AFQ) ordering phase of CeB₆. Assuming the AFQ order in the 4f states but without any lattice distortion, we obtain the TS intensity comparable to the RXS intensity, owing to the anisotropic charge distribution of 4f states. The present calculation reproduces well the interference pattern between the TS and RXS terms for the (\\frac52\\frac32\\frac32) spot observed in the recent experiment. The results suggest that the TS signal as well as the main-peak of the RXS signal are a direct reflection of the AFQ order in CeB₆. In addition, we add the analysis of the temperature and external field dependences of the TS intensity, which may be utilized in determining the possible type of the order parameter.