Regensburg 2010 – scientific programme
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KR: Fachverband Kristallographie
KR 10: Poster: Multiferroics (with MA, DF, KR, DS)
KR 10.18: Poster
Tuesday, March 23, 2010, 10:45–13:45, Poster A
Separation and magnetic-field dependence of contributions to the magnetically induced net polarization in multiferroic TbMn2O5 — •Naëmi Leo1, Thomas Lottermoser1, Dennis Meier1, Roman V. Pisarev2, and Manfred Fiebig1 — 1HISKP, Universität Bonn — 2Ioffe Physical Technical Institute, Russian Academy of Sciences
Strong magnetoelectric coupling is expected in multiferroics in which the ferroelectric polarization is directly induced by the magnetic order. A particularly interesting magnetoelectric multiferroic is TbMn2O5, which shows a reversal of the spontaneous ferroelectric polarization P upon application of a magnetic field. Theoretical approaches predict two contributions to the net polarization directly linked to the magnetic order of the system.
The analysis of nonlinear spectra of TbMn2O5 measured by optical Second Harmonic Generation (SHG) reveals not only two but three distinct contributions P1Mn, P2Mn and P3Tb, whereas in pyroelectric measurements only the net polarization can be seen. It has been shown that the third contribution P3Tb is linked to the magnetic order of the Tb sublattice. Furthermore, spatial resolved measurements reveal additional domain structures at low temperatures.
Performing nonlinear optical measurements in an applied magnetic field reveals that the change of sign in the ferroelectric net polarization in TbMn2O5 is driven by an magnetoelectric interaction with the rare-earth order: P(T,B)=P1Mn(T) − P2Mn(T,H) ± P3Tb(T,H). This work was supported by the DFG through SFB 608.