Dresden 2011 – scientific programme
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KR: Fachgruppe Kristallographie
KR 5: Poster Multiferroics (Joint Session of MA, DF, DS, KR, TT)
KR 5.56: Poster
Tuesday, March 15, 2011, 10:45–13:00, P2
Multiferroics: Magnetic Structures & Excitations — •Simon Holbein1, Max Baum1, Thomas Finger1, Navid Qureshi1, Jeannis Leist3, Götz Eckold3, Petra Becker2, Ladislav Bohatý2, and Markus Braden1 — 1II. Physikalisches Insittut, Universität zu Köln — 2Institut für Kristallographie, Universität zu Köln — 3Institut für Physikalische Chemie, Georg-August-Universität Göttingen
Multiferroics possess 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 and magnetocapacitance effects, among them MnWO4, TbMnO3 and the pyroxenes (Na/Li)FeSi2O6.
We already presented time resolved measurements of magnetoelectric switching in MnWO4. Stroboscopic techniques were applied in order to investigate how fast the magnetic chirality adapts to an instantaneously switched electric field. Recently we arranged a new set-up to investigate the corresponding behaviour of the electric polarisation at such electric fields.
Our results on the magnetic structure of NaFeSi2O6 reveal that the moments arrange in a helical spiral. Therefore the Dzyaloshinski-Moriya interaction is not explaining the development of electrical polarisation (a cycloidal spiral would be needed for this). We extended our investigations on electric field driven switching of magnetic chirality to NaFeSi2O6.
Furthermore we discuss the electromagnon - collective spin-phonon excitations - in DyMnO3.