Resonant X-ray scattering of PrRuP

Ishii, Kenji; Tsubota, Masami; Inami, Toshiya; Tsutsui, Satoshi*; Hao, L.*; Hasegawa, Tomoo*; Iwasa, Kazuaki*; Murakami, Yoichi; Sugawara, Hitoshi*; Saha, S. R.*; Sato, Hideyuki*

PrRuP shows a metal-insulator (MI) transition at 62 K accompanied by a structural phase transition. Because LaRuP without electrons does not shows the MI transition, electrons in the Pr atom plays an important role in the transition. In order to elucidate a modulation of electronic states of Pr, we have carried out a resonant X-ray scattering study of PrRuP at Pr - and -edges. Below , resonant signal at the absorption main-edge was successfully observed at the superlattice reflections of the modulation vector in addition to the energy-independent component from the lattice distortion. Because the reflection contains the difference of anomalous scattering factors between two Pr atoms in the unit cell, two different electronic states are actually ordered below . Furthermore we found that the polarization of X-ray is mostly unrotated even at the resonance, which indicates that the resonant scattering in PrRuP is almost isotropic.