Optimizing the Magnetic Properties of Metallic Magnetic Tip for Observation of Clear Magnetic and Dielectric Domains in Various BiFeO₃-Based Multiferroic Thin Films Induced by a Local Electric Field

To optimize the magnetic properties of metallic magnetic tips for observing distinct magnetic and electric domains using magnetic force microscopy (MFM) and electric force microscopy (EFM) in various Bismuth ferrite (BiFeO₀; BFO) based multiferroic thin films, various metallic magnetic tips with different magnetic properties were used.In particular, the MFM and EFM images of various BFO based multiferroic thin films, (Bi₀ .5 La₀ .5 )(Fe₀ .₀Co₀.₀)O₀ and (Bi₀ .5 Nd₀ .5 )(Fe₀ .₀Co₀.₀)O₀ with different saturation magnetization (M₀ ), were observed.The thickness of these films is 200 nm and 260 nm.These thin films were observed by metallic and magnetic Co-Cr-Pt coated MFM tips (30 nm thick) with varying M₀ values.As the M₀ of the Co-Cr-Pt coating tip increased, the MFM phase signal increased, while the EFM phase signal declined and even changed polarity.The reduction or change in the EFM signal observed by the metallic and magnetic Co-Cr-Pt-coated MFM tip with the higher M₀ values was attributed to the very strong magnetic force, which dominates the electric force.By evaluating MFM and EFM images of BFO based thin films with various total magnetic moments (M s × film thickness) using tips with various M s , we found that there is an ideal combination of tip and BFO based thin film that provides phase signals of sufficient strength with the correct polarity in all images.These findings highlight the importance of selecting an MFM tip with appropriate magnetization to achieve accurate domain imaging in BFO based multiferroic thin films, which is crucial for advancing highresolution characterization of magnetoelectric interactions.