Correlation between magnetic ordering and electric polarization in YMn1-xFexO3 nanocrystalline materials

We have synthesized a series of pure hexagonal YMn1-xFexO3 (0 <= x <= 0.2) nanocrystalline materials by a modified Pechini method and study the effect of substituting Fe for Mn on the antiferromagnetic (AFM) phase transition in YMnO3 nanocrystalline materials using magnetic and dielectric measurements. The magnetic characterization indicates that with increasing Fe-content, up to 0.2, the AFM transition temperature increases from 60 to 72 K. Variable temperature dielectric measurements show an anomaly in the dielectric constant at temperatures close to the AFM ordering temperature for all of the compositions. A corresponding shift of the peak-positions of the dielectric anomaly and magnetic ordering indicates a unique correlation between the magnetic ordering and the electric polarization. The enhancement of the multiferroic ordering temperature in YMn1-xFexO3 nanocrystalline materials is explained on the basis of an increase in the covalence of the Mn/Fe-O-Mn/Fe bonds with iron doping. (C) 2012 American Institute of Physics. [doi:10.1063/1.3673412]