High-Frequency Magnetic Field Energy Imaging of Magnetic Recording Head by Alternating Magnetic Force Microscopy with Superparamagnetic Tip

Le résumé fourni par la source

Recent progress of high frequency (HF) magnetic materials and devices requires the precise imaging of HF magnetic fields. We have designed Alternating Magnetic Field Microscopy (A-MFM) with a superparamagnetic (SP) tip as a method to image HF magnetic field energy (MFE) near sample surface. The spatial resolution of MFE was confirmed to be better than that of magnetic field itself, due to shorter range interaction. In this work, we applied the method to image the MFE of magnetic writing head of perpendicular magnetic recording system. We applied amplitude modulated HF current with low modulation frequency of 89 Hz to the head and we imaged HF MFE by using the frequency modulated cantilever oscillation which was caused by low frequency magnetic force from the interaction between SP tip and the field.The imaging has been performed in a broad carrier frequency range 0.1 - 1000 MHz with minimal detectable wavelength of about 20 nm. We demonstrated the absence of image quality degradation with increasing field frequency. The magnetic spot size was close to the geometrical pole dimension, indicating the low tip-sample distance and minimal distortion.

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