Resonant X-ray scattering of PrRu4P12

We have performed resonant X-ray scattering study on PrRu4P12 at the Pr L-2 and L-3 edges. Below the metal-insulator transition temperature (T-MI similar or equal to 62K), resonant signal appears in the superlattice reflections in addition to the lattice distortion, which demonstrates that different electronic states of the Pr atoms are alternatingly ordered in the BCC unit cell. Polarization analysis of the scattered X-ray shows that the intensity changing the polarization from pi to sigma is absent or very weak. This means that the difference of the anomalous scattering factor between two Pr atoms in the BCC unit cell, which reflects the character of the intermediate 5d states of the resonant process, is almost isotropic. (c) 2006 Elsevier B.V. All rights reserved.