Dresden 2006 – scientific programme
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TT: Tiefe Temperaturen
TT 31: Correlated Electrons: Metal Insulator Transition - Part 2
TT 31.1: Talk
Thursday, March 30, 2006, 14:00–14:15, HSZ 301
The spin states of LaCoO3; a revision revised — •M. W. Haverkort1, Z. Hu1, J. C. Cezar2, H. Wu1, J. Gegner1, T. Burnus1, T. Koethe1, H. Hartmann1, M. Reuther1, T. Lorenz1, A. Tanaka3, N. B. Brookes2, H. H. Hsieh4, H.-J. Lin5, C. T. Chen5, and L. H. Tjeng1 — 1II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany — 2European Synchrotron Radiation Facility, Boîte Postale 220, 38043 Grenoble Cédex, France — 3Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530, Japan — 4Chung Cheng Institute of Technology, National Defense University, Taoyuan 335, Taiwan — 5National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu 30076, Taiwan
Using soft x-ray absorption spectroscopy and magnetic circular dichroism at the Co-L2,3 edge we show that the spin state transition in LaCoO3 can be well described by a low-spin ground state and a high-spin first excited state which becomes populated at elevated temperatures. Sum rules used on the magnetic circular dichroism signal reveal a large orbital momentum, in good agreement with a low-/high-spin scenario, but hard to reconcile with a low-/intermediate-spin picture. We discuss why the original prediction of the intermediate-spin state from band theory may be questionable.