High-frequency MFM (HF-MFM) characterization of magnetic recording writer poles

A high-frequency MFM (HF-MFM) is built up for the observation of the high-frequency stray fields of harddisk write heads, using a commercial AFM/MFM system as a basis. In this contribution, the amplitude-modulation technique were employed, where an amplitude-modulated current was applied to the head coil in order to detect the force gradient induced by the HF magnetic field. The piezo element is still used to vibrate the cantilever, so that a dual-vibrational technique results. Here, the cantilever is oscillated by the piezo element and the HF magnetic field from the writer pole.