Calibration of Coercive and Stray Fields of Commercial Magnetic Force Microscope Probes

Variable-field magnetic force microscope (MFM) is introduced to characterize the magnetic behavior of commercially available MFM probes that is relevant to interpret MFM imaging. A Nanotec Electronica S.L. microscope has been conveniently modified to apply magnetic fields in axial direction (up to 1.5 kOe) and in-plane direction (up to 2.0 kOe). Axial and transeverse hysteresis loops of the probes have been generated by measuring the changes in the MFM contrast observed when the magnetic field is applied. The variation of the MFM signal is ascribed to the modification of the magnetic state of the tips. This is enabled by the large coercitivity (~1.7 kOe) of the checked longitudinal recording media. The properties of the probes depend on the coating material, the macroscopic tip shape, and tip radius. In only a few cases, the magnetization of the probe can be oriented along in-plane orientation. In addition, the stray field of the tips has been deduced by measuring the influence of the probe in the magnetic state of the checked samples.