Anomalous spin-density distribution on oxygen and Ru in Ca1.5Sr0.5RuO4:: Polarized neutron diffraction study -: art. no. 087202

By means of polarized neutron diffraction in a magnetic field of 7.0 T at 1.6 K an anomalously large magnetization density is observed on the in-plane oxygen in Ca1.5Sr0.5RuO4. Field-induced moments of different ions are determined by refinement on the flipping ratios, yielding mu(Ru)=0.346(11)mu(B), mu(O1)=0.076(6)mu(B), and mu(O2)=0.009(6)mu(B). The moment on the oxygen arises from the strong hybridization between the Ru-4d and O-2p orbitals. The maximum entropy magnetization density reconstruction reveals a strongly anisotropic density at the Ru site, consistent with the distribution of the xy (t(2g) band) d orbitals.