Magnetic ordering in the frustrated pyrochlore Yb2Ru2O7

Yb2Ru2O7 was studied using neutron diffraction and muon spin relaxation measurements to investigate the effect of the Yb anisotropy and Yb-Ru exchange interaction on the magnetic ordering transitions in this material. The Ru moments order into a long range ordered state below 85 K, while the Yb moments start to freeze/order below 20 K, which is at a higher temperature as suggested by previous reported bulk measurements. No structural distortions are observed at the magnetic transitions. Representational analysis shows that the ordering of the Ru and Yb moments can be described by the same irreducible representation. The two magnetic sublattices are, however, antiferromagnetically coupled. Unlike what has been suggested by bulk measurements and has been observed in other members of this family of Ru pyrochlores, the Yb single ion planar anisotropy, surprisingly, does not influence the Ru moment ordering. The ordering of the Ru moments, on the other hand, does influence freezing/ordering of the Yb moments.