Interface polarity brings a way to modulate magneto-optical effect of cubic Ni 2+ /Fe 3+ co-doped Bi 25 FeO 40 film: Implications in piezoelectricity

Cubic Sillenite Bi 25 FeO 40 (BFO) could become a new magneto-optical material due to its high concentration of Bi 3+ and no birefringence. But its weak magnetism causes the magneto-optical properties to be far from the requirements of practical applications. Doping magnetic Fe 3+ and Ni 2+ ions to improve the magnetism and magneto-optical properties of BFO (Bi 19 Ni 2.8 Fe 4.2 O 40 ) film on fluorine-doped tin oxide (BNFO/FTO) is discussed in this paper. Another focus of this paper is to discuss the magneto-optical properties modulated by the electric field. The cubic BNFO film has weak piezoelectric effects, which makes it difficult to modulate its magneto-optical effect by electric field. A polarity symmetry induced by the Schottky junction between Au metal layer and BNFO semiconductor layer (Au/BNFO) compensates for cubic symmetry, and the piezoelectric effect can be improved. By applying an electric field, its magnetic circular dichroism (MCD) ellipticity | ΨF | gradually decreases as a direct current voltage from 0 V to 10 V in a magnetic field of 2500 Oe, demonstrating the feasibility of this strategy. These results indicate a new way for highly symmetric magneto-optical materials to modulate magneto-optical effects in electric fields.