Regensburg 2016 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 11: Poster

DF 11.12: Poster

Mittwoch, 9. März 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 Pimenov¹ — ¹Institute 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.