Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 65: Time-resolved spectroscopies III
O 65.3: Vortrag
Freitag, 27. März 2009, 11:45–12:00, SCH A315
Femtosecond melting of orbital order in magnetite — •Niko Pontius1, Torsten Kachel1, Hermann A. Dürr1, Christian Schüßler-Langeheine2, Bill Schlotter3, Martin Beye3, Alexander Föhlisch3, and Wilfried Wurth3 — 1Helmholtz-Zentrum Berlin, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin — 2Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln — 3Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg
The Verwey transition in magnetite (Fe3O4), discovered by Verwey in 1939 [1], takes place at TV≈120K and becomes manifest in a metal-to-insulator transition as well as a structural phase transition, leading to the appearance of superstructure x-ray diffraction peaks. Recent soft x-ray diffration (RSXD) experiments confirm charge and orbital order in the low temperature phase [2]. However, the microscopic origin of the transition,is still controversial.
By using time-resolved RSXD we investigate the "melting" of charge and orbital order to get a more detailed insight into the driving forces of the transition, in partitular the interplay of structural and electronic degrees of freedom. The Verwey transition is induced from below TV by absorbing an infrared fs-laser pulse. The subsequent temporal evolution of the orbital order is probed by RSXD using fs x-ray pulses the free electron laser FLASH in Hamburg.
[1] E.J.W. Verwey, Nature 144, 327-328 (1939)
[2] J. Schlappa et al. , Phys. Rev. Lett. 100, 026406 (2008)