Magnetic force microscope (MFM) was used to characterize the L10 ordered FePt(001) films sputter deposited directly on MgO(001) substrates at an elevated temperature. With the change of nominal thickness (tN), the morphology varied from isolated particles to continuous films. The coercivity showed a marked change at the percolation boundary of tN≅45 nm, where the film morphology changed from a discontinuous to a continuous state. Below tN=45 nm, the coercivity did not change apparently, though the number of single-domain particles increased gradually with decreasing tN. At tN=20 nm, a critical (maximum) size of single domain particles, d=180 nm, was obtained from a size distribution, which was taken from the atomic force microscope/MFM measurement. The value calculated for this critical size was found to be d=155 nm in the assumption that the particles had ellipsoidal shape. The slight difference between experimental and theoretical values is likely to be attributed to an axis ratio (c/a) distribution of particles.
Abstract-High-coercivity CoPt magnetic force microscope tips have been modified by focused ion beam milling to improve the resolution of magnetic domain images. The magnetic materials around the apex have been removed, leaving a 30-nm diameter magnetic particle at the tip end. Due to the smaller amount of magnetic material, the stray field from this new tip is significantly reduced, and the spatial resolution of the magnetic domain images is improved. The tip is used to obtain high-resolution domain images of a CoCrPt-SiO 2 /Ru perpendicular recording medium with linear recording densities from 800 to 1000 kfci. Magnetic patterns of 900 kfci, corresponding to a bit size of 28 nm, are well resolved. From the analysis of the power spectrum of the track profiles for these images, a spatial resolution as good as 11 nm under ambient conditions with a commercial magnetic force microscope is achieved.Index Terms-Domain images, focused ion beam technology, magnetic force microscopy, magnetic recording.
A dot-by-dot analysis to investigate the magnetization switching behavior of the perpendicular patterned CoCrPt medium is reported. The medium is investigated by in situ and ex situ magnetic force microscopy (MFM) techniques. The topographical and magnetic characteristics of each magnetic dot were studied in given areas. The perpendicular dc demagnetization (DCD) remanence data evaluated by counting the volume of reversed magnetic dots according to the ex situ MFM measurements were in good agreement with alternating gradient magnetometry measurements. The influence of the magnetostatic energy associated with nanodots to the distribution of the intrinsic coercivity of individual magnetic dots and the intrinsic DCD curve of the medium are estimated. Further, the mechanism of magnetization reversal of individual magnetic dot is discussed.
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