Piezoelectricity Induced by Interface Polarity Brings a New Way to Modulate Magneto-Optical Effect of Cubic Ni2+/Fe3+ Co-Doped Bi25feo40 Film

Abstract

Ni2+ and Fe3+ ions are co-doped into Bi25FeO40 (BNFO), and then a multilayer film of Au/BNFO/FTO is constructed in this paper. The magnetic circular dichroism (MCD) ellipticity |ΨF| of Au/BNFO/FTO film is 3438 deg.·cm-1 at 361.2 nm, which is stronger than that of the garnet Ce3+:YIG film. The Schottky junction shows at the interface between the metal layer of Au and the semiconductor layer of BNFO, which builds a built-in electric field and then induces polarity symmetry. Even if BNFO has a high-symmetry cubic structure, the piezoelectric effect can still be generated. Therefore, it is possible for the magneto-optical effect of weak piezoelectric BNFO films to be modulated by the electric field. By applying an electric field, the piezomagnetic effect together with the converse piezoelectric effect can modulate the MCD signal of the composite Au/BNFO/FTO film, demonstrating the feasibility of this strategy.

Keywords: Au/BNFO/FTO film, Magneto-optical effect, piezoelectric effect, Magneto-electric coupling