Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 12: Correlated Electrons - Spin Systems and Itinerant Magnets: Experiment

TT 12.8: Vortrag

Samstag, 5. März 2005, 12:30–12:45, TU H2053

Co-L_2,3 XMCD study on one-dimensional Ca₃Co₂O₆ single crystals — •Z. Hu¹, M.W. Haverkort¹, J. Gegner¹, A. Maignan², N.B. Brookes³, J.C. Cezar³, and L.H. Tjeng¹ — ¹II. Physikalisches Institut, Universität zu Köln — ²Laboratoire CRISMAT, Caen, France — ³European Synchrotron Radiation Facility, Grenoble, France

We have carried out x-ray magnetic circular dichroism (XMCD) measurements at the Co-L_2,3 edges on single crystals of Ca₃Co₂O₆, in which Co(1)O₆ octahedron alternates with Co(2)O₅ trigonal prism along the chain. We found that the dichroism in the L₃ edge mainly occurs in the lower part of the spectrum and that the dichroism in the L₂ edge is negligible. In combination with cluster model simulations, we deduce that the dichroism originates from the trigonal prism Co³⁺(2) ions which are in the high spin state and that the octahedron Co³⁺(1) ions are nonmagnetic, i.e. in the low spin state. From the orbital sum rule we obtain an orbital moment of 1.2 µ_B for the Co³⁺(2).