Regensburg 2010 – scientific programme
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DS: Fachverband Dünne Schichten
DS 7: [MA] Multiferroics I (Joint Session of MA/DF/KR/DS)
DS 7.9: Talk
Monday, March 22, 2010, 12:30–12:45, H3
Topological magnetoelectric memory effect in the spin-spiral multiferroic MnWO4 — •Dennis Meier1, Naemi Leo1, Thomas Lottermoser1, Petra Becker2, Ladislav Bohatý2, and Manfred Fiebig1 — 1HISKP, Universität Bonn — 2Institut für Kristallographie, Universität zu Köln
Within the field of multiferroics, i.e. compounds with coexisting magnetic and electric order, so-called spin-spiral ferroelectrics attract tremendous attention. In these systems magnetic long-range order violates the inversion symmetry and induces a spontaneous electric polarization. Magnetic and electric domains are thus rigidly coupled so that “giant” magnetoelectric effects are obtained. However, up to now nearly nothing is know about the topology of the domain state in these systems. We report spatially-resolved measurements of the multiferroic domain topology in MnWO4. For the first time, the full three-dimensional domain structure in a spin-spiral system is imaged. Our study reveals that the multiferroic domains in magnetically-induced ferroelectrics unify features that are associated to a magnetic domain state and others that point unambiguously to ferroelectric domains. Hence, a description in terms of ferroelectric or antiferromagnetic domains is incomplete and no longer appropriate. The novel concept of “multiferroic hybrid domains” is introduced. Annealing cycles reveal a topological memory effect: Due to phase coexistence at one phase boundary limiting the multiferroic state in MnWO4, the entire multiferroic multidomain state can be reconstructed subsequent to quenching it. This work is supported by the DFG through SFB608.
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