Magnetic and Dielectric Studies on Cobalt Substituted BiFeO3

Abstract

This thesis presents the study of structural, surface morphology, electric, magnetic, magnetoelectric and magnetodielectric properties of Cobalt substituted multiferroic BiFeO3.
Since their discovery, multiferroics have brought tremendous interest among the researchers due to the coexistence of various ferroic order parameters. The synchronization of the magnetic and electric order parameter, hence generating magnetoelectric coupling, has been of importance in particular. Various functional devices aiming at the coupling between the ferroelectric and ferromagnetic order parameter are underway. Among all, the perovskite oxides (ABO3) based multiferroics are of prime interest due to their ease of synthesis and easy to understand physical interactions due to their simple structure.
Bismuth Ferrite (BiFeO3), is a prototype ABO3 type multiferroic material, possessing the ferroelectric Curie temperature (Tc) ~ 1103K and antiferromagnetic Neel temperature (TN) ~ 643K. It exhibits a weak net magnetization as the G- type magnetic ordering is superimposed with an incommensurate cycloidal spin structure having the periodicity of 62nm. The chemical substitution is considered as one of the alternatives for enhancing the net magnetization via disruption of the cycloidal chain. Among the various B–site substitution, the Co substituted BiFeO3 is found to be very rare in the literature.