Investigation of Bloch wall fine structures by magnetic force microscopy

SUMMARY Using a magnetic force microscope (MFM), measurements have been performed on single crystal iron whiskers. These samples exhibit a comparatively simple magnetic domain structure and a high degree of crystallographic perfection. STM measurements yield an average surface corrugation of about 3 nm. These nearly ideal boundary conditions permit an investigation of the undistorted surface configuration of Bloch walls in a cubic bulk crystal. Interactions between the stray field configuration of the sample and a ferromagnetic microscope tip have been measured with a new MFM device which is based on direct compliance detection. Measurements have been performed in the constant‐current mode, as well as in the constant‐compliance, mode. Control observation by means of the Kerr magneto‐optic effect permit an interpretation of the obtained MFM data in terms of isolated 180° Bloch walls. The fine structure of these walls has been analysed and compared with results obtained from model calculations.