A comparative study of magnetic and dielectric behaviors for La 1-xBi xMn 1-yFe yO 3 series (with x=0.5, 0.7 and y=0.3, 0.7)

Abstract

We have carried out an extensive investigation into the effect of doping on both the A- and B-sites for the multiferroic La 0.5Bi 0.5Mn 0.5Fe 0.5O 3 in relation to its physical properties. The temperature dependent magnetization and dielectric response are determined for different percentages of Bi- and Fe-substitutions. For La 0.5Bi 0.5Mn 0.7Fe 0.3O 3, there is a prominent ferromagnetic transition T C around 110K, whereas the other La 0.5Bi 0.5Mn 0.3Fe 0.7O 3 and La 0.3Bi 0.7Mn 0.3Fe 0.7O 3 phases fail to exhibit any clear transition. On the other hand, for the Fe-rich phases, the coercive field increases to 2450Oe compared to 1720Oe (for the Mn-rich phase). All the compositions exhibit coexistence of ferromagnetic and antiferromagnetic phases at low temperatures. The temperature dependent dielectric constant of the investigated samples varies from 32000 to 500 at room temperature and the data has been analyzed using the universal dielectric response model. © 2012 IOP Publishing Ltd.