Berlin 2012 – scientific programme
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DF: Fachverband Dielektrische Festkörper
DF 4: Multiferroics II (jointly with MA, DS, KR, TT)
DF 4.6: Talk
Monday, March 26, 2012, 16:30–16:45, EB 301
Neutron scattering studies on chiral multiferroics: magnetic structure and excitations — •Max Baum1, Thomas Finger1, Jeannis Leist2, Karin Schmalzl3, Paul Steffens3, Petra Becker4, Ladislav Bohatý4, Götz Eckold2, and Markus Braden1 — 1II. Physikalisches Institut, Universität zu Köln — 2Institut für Physikalische Chemie, Georg-August-Universität Göttingen — 3Institut Laue Langevin (ILL), Grenoble — 4Institut für Kristallographie, Universität zu Köln
Multiferroic materials or compounds with a strong magnetoelectric effect posses a large application potential in data storage techniques. Quite recently, systems with a peculiar spiral magnetic order were shown to directly induce a spontaneous electric polarisation and to exhibit giant magnetoelectric effect. Neutron scattering with spherical polarisation analysis gives access to the chiral component of the magnetic structure which is directly linked to the electric polarisation. Therefore, it is possible to control the chiral components by an external electric field. We present neutron scattering experiments on IN14 and IN20 using spherical polarisation analysis documenting the poling of the elastic magnetic chiral terms for MnWO4, TbMnO3 and Ni3V2O8 by cooling in an electric field. In addition, it is possible to switch the chiral components by varying the electric field at constant temperature; thereby measuring multiferroic hysteresis curves. For MnWO4, this experiment was performed with time resolution detecting the typical relaxation times. Tor TbMnO3 we discuss a newly discovered excitation which exhibits a chirality opposite to the static one.