The effect of structural and chemical perturbations in multiferroic BiFeO$_{3}$ epitaxial films

The compatibility between the lone-pair driven ferroelectric distortion and antiferromagnetic order in BiFeO$_{3}$ attracts a lot of attention. A detailed understanding of ferroelectric properties in BiFeO$_{3}$ is gained by investigating the effect of structural/chemical perturbations in strained epitaxial films with chemical modifications. Our work shows that the ferroelectric polarization along [111] exhibits weak dependency on epitaxial strain on a (001) substrate. To examine the role of distortions induced by magnetic ions, we have grown BiFe$_{1-x}$Cr$_{x}$O$_ {3}$ epitaxial films and observed a ferroelectric to antiferroelectric transition with increasing the Cr content. Furthermore, epitaxial films of Bi$_{1-y}$Ba$_{y}$FeO$_{3}$ were grown to investigate the effect of structural variation in connection with change in the valence of Fe ion. The results reveal a high stability of the ferroelectric distortion in epitaxial BiFeO$_{3}$ films.