Abstract
Resonant x-ray diffraction performed at the and absorption edges of Ru has been used to investigate the magnetic and orbital ordering in single crystals. A large resonant enhancement due to electric dipole transitions is observed at the wave-vector characteristic of antiferromagnetic ordering. Besides the previously known antiferromagnetic phase transition at , an additional phase transition, between two paramagnetic phases, is observed around 260 K. Based on the polarization and azimuthal angle dependence of the diffraction signal, this transition can be attributed to orbital ordering of the Ru electrons. The propagation vector of the orbital order is inconsistent with some theoretical predictions for the orbital state of .
- Received 30 April 2005
DOI:https://doi.org/10.1103/PhysRevLett.95.136401
©2005 American Physical Society