Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 26: Metal-Insulator Transition
TT 26.11: Vortrag
Donnerstag, 29. März 2007, 16:45–17:00, H19
t2g orbital order in magnetite — •C. F. Chang1, C. Schüßler-Langeheine1, J. Schlappa1, H. Ott1, M. W. Haverkort1, M. Buchholz1, Z. Hu1, A. Tanaka2, D. Schmitz3, E. Schierle4, E. Weschke4, G. Kaindl4, and L. H. Tjeng1 — 1II. Physikalisches Institut, Universität zu Köln — 2ADSM, Hiroshima University — 3HMI c/o BESSY — 4Institut fur Experimentalphysik,Freie Universität Berlin
The electronic structure of the low-temperature phase of magnetite (Fe3O4) has been a puzzle for many decades. Recent resonant soft diffraction experiments provided first direct evidence for charge order in this system. Using resonant soft x-ray diffraction at the Fe L2,3 resonance we found further evidence for orbital order in this system, which can be recognized from a pronounced polarization dependence of the scattered signal. Due to the cubic-to-monoclinic phase transition in magnetite, the low temperature phase usually consists of multiple twins with different crystalline orientations, which leads to ambiguities in the quantitative analysis of the polarization dependence. By applying epitaxial strain and weak magnetic fields to a thin film of magnetite we are able to reduce the number of crystalline twins in the low temperature phase. With the set of spectra taken from this partially un-twinned sample, a quantitative analysis of the character of orbital-order in magnetite becomes feasible. Supported by the DFG through SFB 608.