High Coercivity and Resolution FePt•MgO-coated Tip for Imaging the Magnetic Field of Perpendicular Magnetic Write Head by Alternating Magnetic Force Microscopy (A-MFM)

Abstract

High coercivity FePt•MgO films were successfully synthetized on cone-shape Si tips in a very high frequency (VHF) plasma irradiation-assisted magnetron sputtering system to prepare the MFM tips for evaluation of the AC magnetic field of perpendicular magnetic write head at high write current. Alloying with MgO significantly enhanced the coercivity of the magnetic coating due to the isolation of FePt grains by MgO. As a result, a high coercivity close to 20 kOe was achieved. The AC magnetic field images of the perpendicular magnetic write head at high write current were taken on alternating MFM (A-MFM) by this tip. A clear amplitude image with a strong signal at the main pole position was observe compared to the pure FePt layer-coated tip, which gave a blurry image and very small amplitude. Fourier analysis of the images obtained by this kind of FePt•MgO tip gives a spatial resolution of about 15 nm in air atmosphere. It is clear that the cone-shape FePt•MgO-coated MFM tip with a coercivity higher than the magnetic field to be measured is effective and capable for measuring the high AC magnetic field for an HD perpendicular magnetic write head at a very high write current.