Resonant soft x-ray Bragg diffraction at the Dy M4,5 edges has been exploited to study Dy multipole motifs in DyB2C2. Our results are explained introducing the intra-atomic quadrupolar interaction between the core 3d and valence 4f shell. This allows us to determine for the first time higher order multipole moments of dysprosium 4f electrons and to draw their precise charge density. The Dy hexadecapole and hexacontatetrapole moment have been estimated at -20% and +30% of the quadrupolar moment, respectively. No evidence for the lock-in of the orbitals at T_N has been observed, in contrast to earlier suggestions. The multipolar interaction and the structural transition cooperate along c but they compete in the basal plane explaining the canted structure along [110].
@article{arxiv.cond-mat/0603048,
title = {High-order Dy multipole motifs observed in DyB2C2 with resonant soft x-ray Bragg diffraction},
author = {A. M. Mulders and U. Staub and V. Scagnoli and S. W. Lovesey and E. Balcar and T. Nakamura and A. Kikkawa and G. van der Laan and J. M. Tonnerre},
journal= {arXiv preprint arXiv:cond-mat/0603048},
year = {2009}
}