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Regensburg 2016 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 11: Poster

DF 11.12: Poster

Wednesday, March 9, 2016, 18:00–20:00, Poster E

Coupling between spin and charge degrees of freedom in multiferroic DyMnO3 from dielectric spectroscopy. — •Markus Schiebl1, Alexey Shuvaev1, Anna Pimenov1, Graeme Eoin Johnstone1, Uladzislau Dziom1, Thomas Kain1, Wilfried Schranz2, Alexander Mukhin3, Vsevolod Ivanov3, and Andrei Pimenov11Institute of Solid State Physics, TU Wien, 1040 Vienna, Austria — 2Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna, Austria — 3Prokhorov General Physics Institute, Russian Academy of Sciences, 119991 Moscow, Russia

In rare-earth manganites (RMnO3) a non-collinear long range cycloidal spin order of the Mn-spins is present in the ferroelectric phase. Above the magnetoelectric phase transition temperature a collinear sinusoidally-modulated spin order is proposed. Based on results by magneto-capacitance and by dielectric spectroscopy, we provide an experimental evidence that the magnetoelectric phase transition in DyMnO3 follows an order-disorder scenario and that a coupling between spin and charge degrees of freedom exists well above the magnetoelectric phase transition. These results suggest the interpretation of the paraelectric sinusoidal phase in manganites as a dynamical equilibrium of magnetic cycloids with opposite chiralities. We provide a free-energy model describing the magnetoelectric phase transition of cycloidal magnetoelectric multiferroics. The model is based on the assumption of a double-well potential and it includes the symmetry-allowed terms up to the second order.

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