TABLE OF CONTENTS In this chapter, magnetic force microscopy is treated in detail with an emphasis on high resolution and hard magnetic materials such as recording media. The chapter starts with basic MFM operation, instrumentation, and a frequency domain theory of image formation using transfer functions. Subsequently, the limits of resolution in MFM are discussed, and the concept of critical wavelength as a measure for resolution is introduced. To achieve high resolution, the tip-sample distance has to be small, and methods of tip-sample distance control are discussed. Finally, generations of MFM tips are treated, including a full silicon micromachined design, which eventually might take the resolution of MFM below 10 nm. [1]
The technique of magnetic force microscopy has been discussed extensively in literature [8] , [12] , [18] , [20], so we will restrict ourselves to a short description. The principle of magnetic force microscopy is very much like that of atomic force microscopy -some even dare to assert that MFM is just an AFM with a magnetic tip, much to the dislike of MFM developers, because in an MFM much smaller forces are measured. In essence, it is true, however, and every MFM is capable of AFM as well (the other way around is not true in general).
In an MFM, the magnetic stray field above a very flat specimen or sample is detected by mounting a small magnetic element, the tip, on a cantilever spring very...
