Magnetic force microscope (MFM) imaging with electrodeposited tips

Since magnetic force microscopy images are influenced by magnetic properties of a tip apex, it is important to characterize its properties and to examine tip-sample interaction. The electrodeposition is useful to make various controlled magnetic tips. We made the MFM tips of electrodeposited FeNi, Co and FeCo films on electrically polished tungsten tips. For measuring a strong field such as that from a recording head, Co tip gives a well contrasted and unsaturated image. For a weak field from a recorded medium, FeCo tip offers a sensitive image. The thickness of the coated tip also affects the images. We studied three different types of tip that are coated with FeCo (about 20 nm, 300 nm, and 2 μm in thickness) by observing a longitudinal recorded medium to compare their sensitivity and resolution. The finest image was obtained with a 300 nm coated tip. As a further study, we demonstrated the utility of magnetotactic bacteria to characterize the magnetic structure of a MFM tip apex