Order-disorder type critical behavior at the magnetoelectric phase transition in multiferroic DyMnO₃

Abstract

We present the results of detailed dielectric investigations of the relaxation dynamics in DyMnO3 multiferroic manganite. A strong low-frequency relaxation process near the paraelectric-ferroelectric phase transition is observed. We provide experimental evidence to show that this relaxation mode corresponds to a chirality switching of the spin cycloid in DyMnO3. We demonstrate that the relaxation dynamics in DyMnO3 is typical for an order-disorder phase transition and may be understood within a simple model with a double-well potential. These results suggest the interpretation of the paraelectric sinusoidal phase in manganites as a dynamical equilibrium of magnetic cycloids with opposite chiralities.