Quadrupole moments in chiral material DyFe3(BO3)4 observed by resonant x-ray diffraction
By means of circularly polarized x-ray beam at Dy L3 and Fe K absorption edges, the chiral structure of the electric quadrupole was investigated for a single crystal of DyFe3(BO3)4 in which both Dy and Fe ions are arranged in spiral manners. The integrated intensity of the resonant x- ray diffraction of space-group forbidden reflections 004 and 005 is interpreted within the electric dipole transitions from Dy 2p3 to 5d and Fe 1s to 4p, respectively. We have confirmed that the 2 handedness of the crystal observed at Dy L3 and Fe K edges is consistent with that observed at Dy M5 edge in the previous study. By analyzing the azimuth scans of the diffracted intensity, the electronic quadrupole moments of Dy 5d and Fe 4p are derived. The temperature profiles of the integrated intensity of 004 at the Dy L3 and the Fe K edges are similar to those of Dy-O and Fe-O bond lengths, while that at the Dy M5 edge does not. The results indicate that the helix chiral orientations of quadrupole moments due to Dy 5d and Fe 4p electrons are more strongly affected by the crystal fields than Dy 4f.