Field-dependent behavior of a magnetic force microscopy tip probed by means of high coercive nanomagnets

Single domain uniformly magnetized CoPt dots are used to probe magnetic force microscopy (MFM) tip characteristics. Magnetic contrasts obtained in MFM experiments are exploited to get the tip hysteresis loop in the influence of the dot. Coercivity, remnant magnetization, as well as details about the magnetization reversal of the tips are obtained. Well defined dot geometries allow a quantitative determination of the stray field of the dots acting on the tip. The tip’s hysteresis loop refers to an effective tip height, involved in the imaging, which is much larger than the extension of a magnetic domain of the CoCr tip coating. When MFM tips and sample dots have widely different characteristics, it is possible to get separate magnetic information, such as hysteresis loops, on both tip and sample, depending on the magnitude of the out-of-plane external field.