Berlin 2015 – scientific programme

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KR: Fachgruppe Kristallographie

KR 3: Poster Session on Ferroic Domain Walls - Multiferroics (DF jointly with KR, MA, TT)

KR 3.20: Poster

Monday, March 16, 2015, 19:00–21:00, Poster C

Inelastic neutron scattering studies on LuFe₂O₄ — •Hailey Williamson¹, Petr Čermák³, Jörg Voigt¹, Ryoichi Kajimoto⁴, Geetha Balakrishnan², and Manuel Angst¹ — ¹Jülich Centre for Neutron Science JCNS and Peter Grünberg Institut PGI, JARA-FIT, Forschungszentrum Jülich GmbH, Germany. — ²Department of Physics, The University of Warwick, UK. — ³Jülich Centre for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Germany. — ⁴Neutron Science Section, MLF Division, J-PARC Centre, Japan

Multiferroic oxides, which exhibit a coupling between magnetism and charge order (CO), constitute a strong and competitive avenue of research. The well-known LuFe₂O₄, the first proclaimed multiferroic through CO due to mixed valence Fe^2+/3+ bilayers separated by Lu monolayers, was initially thought to produce ferroelectricity through polarization, from the specific CO configuration within the bilayers. This fuelled intense investigation, leading to the conclusion through XMCD, bond valence sum analysis of data and macroscopic characterization, that the bilayers are charged and not polar. With much of the static crystallographic and magnetic properties uncovered, it is now essential to elucidate the dynamic properties to understand how the spin and charge are coupled. Here we present quasi-elastic magnetic scattering with a profound temperature dependence, as well as phonon dispersions at higher energies. Finally, we show an indication of a spin gap opening, on cooling through the magnetic ordering temperature.