Berlin 2015 – scientific programme

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MA: Fachverband Magnetismus

MA 22: Multiferroics I (DF with DS/KR/MA/TT)

MA 22.2: Talk

Wednesday, March 18, 2015, 09:45–10:00, EB 107

Critical behavior at the order-disorder transition in multiferroic DyMnO₃ — •Markus Schiebl, Alexey Shuvaev, Anna Pimenov, Graeme Eoin Johnstone, Uladzislau Dziom, and Andrei Pimenov — Institute for Solid State Physics, Vienna University of Technology, 1040 Vienna Austria

We present the results of detailed dielectric investigations of the relaxation dynamics in DyMnO₃ multiferroic manganite. In addition to known domain wall relaxation a second strong mode is observed at low frequencies. We provide an experimental evidence that the new relaxation mode is coupled to the chirality switching of the spin cycloid.

We demonstrate that the relaxation dynamics in DyMnO₃ is typical for an order-disorder phase transition. Therefore, DyMnO₃ follows an order-disorder transition scenario implicating that a short range cycloidal order of Mn-spins exists above T_C. The results suggest that the paramagnetic sinusoidal phase should be explained as a dynamic equilibrium between the clockwise and counterclockwise cycloidal magnetic orders. The short range order in the paraelectric phase is transformed to a long range cycloid at the ferroelectric transition temperature.