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Bismuth ferrite (Bi 2 Fe 4 O 9) thin films were grown on p-type Si (100) substrate by radio-frequency magnetron sputtering at 873 K. X-ray diffraction, field emission scanning electron microscopy and Raman spectroscopy studies revealed that the grown films have single-phase polycrystalline nature and are crystallized in orthorhombic structure. The grain size of the grown thin films was found to increase (56-130 nm) with sputtering power. Atomic force microscopy images clearly illustrated that the grown thin films have smooth surface. Energy-dispersive X-ray analysis revealed the presence of Bi, Fe and O elements with desired ratio and also the absence of impurities in the grown films. Analysis of ferroelectric hysteresis loops revealed that the remanent polarization and coercive field increase with the increase in sputtering power. Vicker's hardness analysis showed that the hardness of films strongly depends on the grain size and film thickness, which are mainly determined by the sputtering power. The above observations revealed that Bi 2 Fe 4 O 9 thin film deposited at higher sputtering power has good crystallinity and shows better electrical properties.

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Bi1−xCaxMnO3 (BCMO) thin films with x = 0, 0.1, 0.2, 0.3 and 0.4 are successfully deposited on the n-type Si (100) substrate at two different temperatures of 400 °C and 800 °C using RF magnetron sputtering. The stoichiometry of the films and oxidation state of the elements have been described by X-ray photoelectron spectroscopy analysis. Dielectric measurement depicts the insulating property of BCMO films. Magnetic and ferroelectric studies confirm the significant enhancement in spin orientation as well as electric polarization at room temperature due to incorporation of Ca2+ ions into BiMnO3 films. The BCMO (x = 0.2) film grown at 400 °C shows better magnetization (Msat) and polarization (Ps)with the measured values of 869 emu / cc and 6.6 μC/ cm2 respectively than the values of the other prepared films. Thus the realization of room temperature ferromagnetic and ferroelectric ordering in Ca2+ ions substituted BMO films makes potentially interesting for spintronic device applications.

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