TABLE OF CONTENTS Magnetic force microscopy (MFM) (Martin and Wickramasinghe 1987, Gr tter et al. 1992) is a slow-scan, raster-type imaging technique that maps a signal issued from the interaction of a tiny magnetic probe, or tip, with the magnetization distribution within the observed sample. The technique has been demonstrated to yield a resolution below some 20 nm in favorable cases with minimal or even no sample preparation. A magnetic force microscope may be operated under ambient conditions or ultrahigh vacuum, allowing the study of clean magnetic surfaces and the link between growth and magnetic properties. Static magnetic fields may be applied to the sample during image acquisition, a necessary condition for correlating magnetic microstructures and hysteresis cycles. Because MFM relies on the interaction of two magnetic bodies, the probe and the sample, MFM is an indirect imaging method. It is potentially perturbative and, thus, may not be termed noninvasive.
A magnetic force microscope (Fig. 1) may be described as composed of a force transducer, a microfabricated cantilever coated with a magnetic thin layer (Gr tter et al. 1990), an x, y, z set of translation actuators, and a signal processing and feedback unit. Various types of forces may act on the tip located at the extremity of the cantilever, among them van der Waals forces when the tip and sample surfaces are brought into close contact, capillary forces owing to an adsorbed water layer when the microscope is operated...
