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Dresden 2011 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 44: Poster Session Correlated Electrons

TT 44.40: Poster

Donnerstag, 17. März 2011, 10:00–13:00, P1

Infrared properties of magnetite under pressure — •Jihaan Ebad-Allah1, Leonetta Baldassarre1, Michael Sing2, Ralph Claessen2, Vic Brabers3, and Christine Kuntscher11Experimentalphysik II, Universität Augsburg, D-86159 Augsburg, Germany — 2Experimentelle Physik 4, Universität Würzburg, D-97074 Würzburg, Germany — 3Department of Physics, Eindhoven University of Technology, 5600 MB Eindhoven, the Netherlands

Magnetite (Fe3O4) crystallizes in the inverse cubic spinel structure and undergoes a Verwey transition at Tv≈120 K at ambient pressure. By applying pressure, Tv decreases with increasing pressure according to the phase diagram proposed in [1]. In addition, it was recently suggested that at room temperature (RT) magnetite undergoes a pressure-induced phase transition from the inverse spinel to the normal spinel structure above 6 GPa, without a change in the lattice symmetry. This proposal is, however, controversially discussed [2].

We studied the electronic and vibrational properties of magnetite by infrared reflectance measurements. First, in order to verify the conduction mechanism via polaron hopping and to search for possible signatures of the phase transition at around 6 GPa, we measured the RT reflectance as a function of pressure. Secondly, we carried out the low-temperature reflectance measurements under pressure in the far-infrared range to check the effect of high pressure on Tv and the splitting of the phonon modes.
G. Kh. Rozenberg et al., Phys. Rev. Lett. 96, 045705 (2006).
S. V Ovsyannikov et al., J. Phys.: Condens. Matter 20, 172201 (2008).

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