Berlin 2012 – scientific programme

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KR: Fachgruppe Kristallographie

KR 3: Joint Session "Multiferroics II - Hexagonal Manganites / Incommensurate Multiferroics" (MA jointly with DF, DS, KR, TT)

KR 3.9: Talk

Monday, March 26, 2012, 17:30–17:45, EB 301

A further step of understanding the complex magnetic order in magnetoelectric Co₃TeO₆ — •Vera Carolus¹, Thomas Lottermoser², Matthias Hudl³, Pierre Tolédano⁴, and Manfred Fiebig² — ¹HISKP, University of Bonn, Germany — ²Department of materials, ETH Zurich, Switzerland — ³Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21 Uppsala, Sweden — ⁴Laboratory of Physics of Complex Systems, University of Picardie, 33 rue Saint-Leu, 80000 Amiens, France

Like most of the known magnetoelectric multiferroics, Co₃TeO₆ exhibits a complex spin structure with a series of consecutive phase transitions. Contrary to common compounds, Co₃TeO₆ possesses two independent commensurate k-vectors in the multiferroic low-temperature phase. In addition, magnetic-field dependent measurements of the ferroelectric polarization show a strongly anisotropic behaviour.

Here we show our results using spatially resolved optical second harmonic generation (SHG) under external magnetic and electric fields in the multiferroic low-temperature phase. However, the SHG gives only access to the magnetic subsystem. Like the ferroelectric polarization, the magnetic structure shows strongly anisotropic behaviour. In crossed magnetic and electric fields we were able to reach a single-domain state, while a magnetic field solely always leads to distinctively different multi-domain states. Most remarkably, for a certain direction of magnetic field, we were able to invert the multi-domain state. Furthermore, this behaviour indicates the existence of a pronounced memory effect.