Co-existence of magnetic and electric ferroic orders in La-substituted BiFeO3

The idea of combining ferroelectricity and ferromagnetism in a single material i.e. multiferroicity, have gained much importance in the development of the technological devices. In this context, the present work explores the effect of La substitution on the structural, ferromagnetic and ferroelectric characteristics of BiFeO3. Various compositions of general formula Bi1-xLaxFeO3 with x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 were prepared by sol-gel auto-combustion method. Powder samples were subsequently calcined at 600 degrees C for 2 h, which manifested rhombohedral phase for 0.0 <= x <= 0.8 and orthorhombic for x = 1.0, as confirmed by X-ray diffraction. Field emission scanning electron microscopy revealed the uniform grain formation with decreasing grain size by increasing La contents. Electron dispersive X-ray spectroscopy revealed the true wt% of the elements in the prepared samples, corresponding to empirical formulae of the composition. The magnetic analysis was performed using a vibrating sample magnetometer and the hysteresis loops of magnetization vs applied magnetic field showed an enhancement in magnetic properties at higher substitution of La at Bi-site. Moreover, remanence, saturation polarization and electric coercive field were also found to be increased with higher La substitution due to decreasing particle size. Hence, modification in multiferroicity by La substitution can be utilized in novel spintronic based device applications.