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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]

A micromagnetic simulation is conducted to study the write field dynamics in the presence of antiferromagnetic exchange coupling (AFC) of writer pole for a perpendicular magnetic recording (PMR) writer head. It is found that, depending on the actual configuration of the AFC coupling in the yoke and the pole tip, there could be an intermediate transient state near zero write field during the magnetization reversal, compared to the normal writer design without AFC coupling. This transient state may cause recording performance degradation. We further investigated the AFC coupling effect on the remanent field in the degauss process. For different performance aspects, i.e., field dynamics, maximum field, and remanent field, the AFC in the yoke and in the pole tip plays different roles. [ABSTRACT FROM AUTHOR]

The characteristics of spatial and temporal field distributions are presented for wrap-around-shielded perpendicular magnetic recording writers. Micromagnetic modeling simulations are conducted to study the effects of shield thickness and the magnetization on the shield-related side field. An improvement of side field is found with the thicker shield thickness and higher saturation magnetization. The maximum side field is spatially and time dependent during the dynamic writing process. The side field reaches the maximum around the transitions, where the write field from the main pole is at the minimum. In addition, the write current rise-time effect on the side field is investigated. [ABSTRACT FROM PUBLISHER]

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]

Abstract: Micromagnetic models of side shielded perpendicular magnetic recording heads show detailed magnetization configuration of the trailing and side shield during the dynamic writing process. The calculation result indicates possible origins of three kinds. The leakage field at the side shield edge, the side shield saturation, and trailing and side shield domain switching. The side shield edge and the saturation induced fields are based on the geometric boundary and they are limited to just around the side shield edge. However the shield switching field can spread to far track position from the side shield to the trailing shield, and it originates from magnetic boundary of the domains and wall formed during the dynamic writing process. As a result, it produces bump field at far track positions in some trailing and side shields. [Copyright &y& Elsevier]

We studied the remanent field from perpendicular writer pole tips by micromagnetic modeling. The pole tip remanence has two causes: 1) the residual flux from the yoke due to undesirable material properties and/or yoke design and 2) the geometry of the pole tip. An optimal yoke design for low remanence includes a wide and short yoke with relatively shallow yoke flare angle around 30° that favors transverse major domains. Horizontal anisotropy in the yoke and the pole tip also helps suppress the vertical magnetization, mainly in the yoke, which yields less residual flux into the pole tip, hence lower remanence. The remanent field is also a strong function of the throat height, i.e., the pole tip length, due to the shape anisotropy effect. Micromagnetic modeling shows that multilayer lamination, both in the yoke and in the pole tip, is an effective way to achieve low remanence. It also eliminates the sensitivity of remanence to the throat height. To improve the robustness of the remanence against the stray field, an antiferromagnetic coupling (AFC) between the lamination layers may also be necessary. Our results apply to both single pole heads and shielded pole heads. [ABSTRACT FROM AUTHOR]

Presents a micromagnetic modeling on the readback process of perpendicular recording with soft underlayer (SUL). Effect of the SUL on readback; Transition response for different SUL saturation magnetization; Rolloff curves of the readback power with linear density for different values of medium thickness.

We present a systematic study of write field asymmetry by using micromagnetic modeling for a perpendicular magnetic recording (PMR) writer structure. Parameters investigated include initial magnetization condition, write current amplitude, write current frequency, and initial write current polarity. It is found that the write current amplitude and frequency (data rate) are the dominant factors that impact the field asymmetry. Lower write current amplitude and higher write current frequency will deteriorate the write field asymmetry, causing recording performance (such as bit error rate) degradation. [ABSTRACT FROM AUTHOR]