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TT: Tiefe Temperaturen
TT 34: Correlated Electrons: Spin Systems and Itinerant Magnets
TT 34.8: Talk
Friday, March 31, 2006, 12:00–12:15, HSZ 301
Investigation of Orbital and Magnetic Order in Ruthenates with Resonant X-ray Diffraction — •Ioannis Zegkinoglou1, J. Strempfer1, B. Bohnenbuck1, C.S. Nelson2, C. Bernhard1, and B. Keimer1 — 1Max-Planck-Institut für Festkörperforschung, D-70569 Stuttgart, Germany — 2National Synchrotron Light Source, Brookhaven National Laboratory, Upton, USA
Resonant x-ray diffraction at the LII and LIII-absorption edges of ruthenium has been used to investigate orbital and magnetic order in 4d transition metal oxide single crystals. A large resonance enhancement of the magnetic scattering cross-section due to electric dipole transitions directly into the 4d band is observed. In the single-layered Mott transition system Ca2RuO4, a new phase transition between two paramagnetic phases is observed around 260 K, at the wave-vector characterizing the low-temperature antiferromagnetic order [1]. Based on the polarization and azimuthal angle dependence of the diffracted intensity, the new phase transition is attributed to the ordering of the Ru t2g orbitals. In RuSr2GdCu2O8, the antiferromagnetic order of Ru ions and the possible effect of the onset of superconductivity on it below Tc ≈ 40 K are investigated. Due to the sensitivity of resonant x-ray diffraction to the azimuthal angle, a precise determination of the direction of the magnetic moment in the system is possible.
[1] I. Zegkinoglou, J. Strempfer et al., Phys. Rev. Lett. 95, 136401 (2005)