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Anharmonicity due to electron-phonon coupling in magnetite

DOI: 10.1103/PhysRevLett.110.207204 DOI Help
PMID: 25167445 PMID Help

Authors: Moritz Hoesch (Diamond Light Source) , Przemysław Piekarz (Institute of Nuclear Physics, Polish Academy of Sciences) , Alexey Bosak (European Synchrotron Radiation Facility) , Mathieu Le Tacon (Max-Planck-Institut für Festkörperforschung) , Michael Krisch (European Synchrotron Radiation Facility) , Andrzej Kozlowski (AGH-University of Science and Technology) , Andrzej M. Oles (Max-Planck-Institut für Festkörperforschung; Jagellonian University) , K Parlinski (Institute of Nuclear Physics, Polish Academy of Sciences)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review Letters , VOL 110 (20) , PAGES 207204

State: Published (Approved)
Published: May 2013

Abstract: We present the results of inelastic x-ray scattering for magnetite and analyze the energies and widths of the phonon modes with different symmetries in a broad range of temperature 125<T<293K. The phonon modes with X4 and delta 5 symmetries broaden in a nonlinear way with decreasing T when the Verwey transition is approached. It is found that the maxima of phonon widths occur away from high-symmetry points, which suggests the incommensurate character of critical fluctuations. Strong phonon anharmonicity induced by electron-phonon coupling is discovered by a combination of these experimental results with ab initio calculations which take into account local Coulomb interactions at Fe ions. It (i) explains observed anomalous phonon broadening and (ii) demonstrates that the Verwey transition is a cooperative phenomenon which involves a wide spectrum of phonons coupled to the electron charge fluctuations condensing in the low-symmetry phase.

Subject Areas: Physics, Materials

Facility: ID28 at ESRF

Added On: 10/12/2014 21:40

Discipline Tags:

Physics Magnetism Materials Science

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