MFM Tip With a Ferromagnetic Disk-Shaped Apex for Large Domain Scanning

We study magnetic force microscopy tips with a ferromagnetic disk-shaped apex (FMD tip). We find that it behaves as a paramagnetic-like tip when scanning large domains, i.e., it visualizes only the domain boundaries. Moreover, it significantly reduces the perturbation of soft magnetic samples and provides a longer probe lifetime compared to commercial low-moment probes. FMD tip was tested on a Co-based sample with out-of-plane magnetization and on a longitudinal magnetic media with in-plane recording. We prepared two FMD tips with disk diameters of 150 and 325 nm in order to analyze how the disk diameter affects the probe sensitivity and the measured width of the domain wall. Experimental results are supported by analytical calculations and numerical simulations.