MFM analysis of recorded bits written by trimmed and untrimmed MR heads

A favourable comparison is made between track widths measured from the analysis of magnetic force microscopy (MFM) images and those measured from spin stand data for tracks written with trimmed and untrimmed magneto-resistive heads onto a high-performance media. The analysis of MFM images of tracks is extended to probe sources of media noise. The signal-to-noise ratio (SNR) measured by MFM is found to be closely related to the relative amplitudes of the various Fourier components of written tracks. The influence on SNR of longer wavelength components attributable to hard transitions is found to decrease with increasing head current. The effect of such hard transition noise is more easily overcome with trimmed heads.