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Geometry of the experiment. A spherical MFM probe of effective radius Rp and magnetic moment m p is positioned at distance z (measured from the center of the probe) from the surface of a magnetic film of thickness t in a magnetic field H 0 applied perpendicular to the film. The effective radius of the probe-sample interaction Ri is shown schematically. In addition, two sample magnetization profiles are shown schematically: (a) the “hard” magnetic case with sample magnetization unaffected by the probe and (b) where film is magnetized by the strong inhomogeneous probe field.
(Color online) MFM images of the static cantilever deflection at several probe-sample distances z = 1093 nm, 986 nm, 900 nm, and 855 nm. zincludes the effective tip radius Rp ∼ 500 nm. The lateral size of the images is 10 × 10 μm2. We attribute the slight asymmetry in the images to the in-plane component of the probe’s magnetic moment m p .
(Color online) Dependence of the MFM force on separation z with the probe centered over the Py disk. Experimental data are obtained from MFM images in Fig. 2. The semi-analytical fit agrees excellently with experiment and returns Ms ≈ 803 G. Micromagnetic modeling results for the same problem are shown for comparison. In addition, the separation dependence of the MFM force that would result if the disk was uniformly magnetized (obtained using Eq. (2)) is presented, clearly demonstrating the influence of the probe field on the magnetization structure of the dot.
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