Possible coexistence of Cycloidal Phases, Magnetic Field Reversal of Polarization and Memory Effect in Multiferroic \emph{R}$_{0.5}$Dy$_{0.5}$MnO$_3$ (\emph{R}=Eu and Gd)

TL;DR

This study reveals coexistence of cycloidal magnetic phases, magnetic field-induced polarization reversal, and memory effects in multiferroic R$_{0.5}$Dy$_{0.5}$MnO$_3$, showcasing their extraordinary magnetoelectric properties and potential for memory applications.

Contribution

It demonstrates the coexistence of different cycloidal phases and novel magnetic field effects in R$_{0.5}$Dy$_{0.5}$MnO$_3$, which was not previously observed in similar multiferroic systems.

Findings

Coexistence of ab and bc cycloidal magnetic phases.

Electric polarization can be reversed by magnetic field.

Presence of non-volatile ferroelectric memory effect.

Abstract

We report the occurrence of both \emph{ab} and \emph{bc} cycloidal ordering of Mn-spins at different temperatures and their possible coexistence at low temperatures in the polycrystalline mixed rare-earth compounds, \emph{R}$_{0.5}$Dy$_{0.5}$MnO$_3$ (\emph{R} = Eu and Gd), which exhibit extraordinary magnetoelectric properties. While the polarization of Gd$_{0.5}$Dy$_{0.5}$MnO$_3$ is comparable to TbMnO$_3$, the compound Eu$_{0.5}$Dy$_{0.5}$MnO$_3$ shows high value of polarization. However, both of them show giant magnetic tunability and exhibit large magnetocapacitance whose sign changes across the two cycloidal ordering temperatures. Intriguingly, the electric polarization can be reversed upon ramping up or ramping down the magnetic field, which has not been observed for any of the \emph{R}MnO$_3$ system. Most strikingly, these compounds show non-volatile ferroelectric memory effect even in the paraelectric and paramagnetic region (T$_C$ $\leq$ T $\leq$ 80 K). We attribute these remarkable properties to the coexistence of \emph{ab} and \emph{bc} cycloidal ordered phases.