Experimental observation of ferrielectricity in multiferroic DyMn2O5: revisiting the electric polarization

TL;DR

This study reveals ferrielectricity in DyMn2O5, characterized by two anti-parallel ferroelectric sublattices originating from different spin interactions, and explores its magnetic and electric properties at low temperatures.

Contribution

It provides the first experimental evidence of ferrielectricity in DyMn2O5, revisiting its electric polarization and magnetic origins with detailed temperature-dependent analysis.

Findings

DyMn2O5 exhibits ferrielectricity with two anti-parallel ferroelectric sublattices.

The sublattices are generated from Mn-Mn and Dy-Mn exchange interactions.

Electric polarization is path-dependent and reflects magnetic transitions.

Abstract

The electric polarization and its magnetic origins in multiferroic RMn2O5, where R is rare-earth ion, are still issues under debate. In this work, the temperature-dependent electric polarization of DyMn2O5, the most attractive member of this RMn2O5 family, is investigated using the pyroelectric current method upon varying endpoint temperature of the electric cooling, plus the positive-up-negative-down (PUND) technique. It is revealed that DyMn2O5 at low temperature does exhibit the unusual ferrielectricity rather than ferroelectricity, characterized by two interactive and anti-parallel ferroelectric sublattices which show different temperature-dependences. The two ferroelectric sublattices are believed to be generated from the symmetric exchange-striction mechanisms associated with the Mn-Mn spin interactions and Dy-Mn spin interactions, respectively. The path-dependent electric polarization reflects the first-order magnetic transitions in the low temperature regime. The magnetoelectric effect is mainly attributed to the Dy spin order which is sensitive to magnetic field. The present experiments may be helpful for clarifying the puzzling issues on the multiferroicity in DyMn2O5 and probably other RMn2O5 multiferroics.