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Magnetization dynamics during field reversal in thin film recording heads are studied via micromagnetic modeling. It is found that head field reversal under the current field can be characterized by two stages: an initial stage that is mainly governed by the gyromagnetic motion and virtually independent of energy damping, followed by a damping stage that strongly depends on the energy damping constant. Due to the finite energy damping in practical recording heads, the head field amplitude will roll off at high recording frequencies. Simply decreasing the current rise time or increasing current amplitude will not alleviate the situation, but rather worsen it. There exists an optimum current rise time at which the head field rise time is minimized and the roll-off frequency is maximized. [ABSTRACT FROM AUTHOR]

This paper presents a study of the degauss process of a perpendicular magnetic writer pole using micromagnetic modeling as a tool. The dynamics of the yoke and the pole-tip magnetization relaxation during degauss are studied in detail, and the remanent field of the pole tip is used as a metric to measure the effectiveness of each of the degauss methods. Various aspects of the degauss current waveforms are investigated, such as frequency, duration, initial current amplitude, amplitude decay envelope, and overshoot. Some alternative waveforms, i.e., unipolar reverse pulse degaussing, have also been examined. It has been found for many of the parameters to have an optimal range outside of which the degauss effectiveness and efficiency are degraded. [ABSTRACT FROM AUTHOR]

Using a dynamic micromagnetic write model, we have studied the spectral signal-to-noise ratio (SNR) performance of perpendicular media using a ring head without soft underlayer (SUL) and compared it with that of longitudinal media. With optimized exchange coupling of the media, the ring head shows good writability on the perpendicular media without SUL. At a linear density of 600 kfci, the ring head/perpendicular media essentially has no SNR gain over the longitudinal media, whereas going to 1000 kfci, the perpendicular media has an advantage of about 4 dB over the longitudinal. Comparison of the ring head (RH) without SUL was also made with the monopole head (MPH) and shielded pole head (SPIt), both with SUL. RH and MPH both have about the same Stoner-Wohlfarth field gradient and SNR performance, whereas at the SNR plateau, SPH yields an SNR about 4-5 dB higher than RH and MPH, thanks to the high field gradient. [ABSTRACT FROM AUTHOR]