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The effect of stress in soft magnetic thin films, in particular, on the in-plane anisotropy, has been studied, based on the analysis of the magnetoelastic energy associated with the stress. The easy-axis directions and the effective anisotropy constants have been identified, as functions of the stress, the magnetostriction coefficients of the material, and the growth texture of the film. The magnetoelastic energy has been combined into an existing micromagnetic model to simulate the magnetization of thin films with various materials, stress states, and growth textures. Simulation results of static magnetic domain structures are in agreement with the theoretical predictions. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

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 perpendicular write head with a stitched pole tip and side yoke recessed from the air-bearing surface is proposed and investigated using three-dimensional micromagnetic modeling. The design yields an increase of head field magnitude by 30% over the conventional single pole head. It is found that the optimal flare angle at the bottom of the yoke is 45°, for maximizing the on-track field magnitude and getting the minimum off-track field at the same time. Reducing the throat height significantly increases on-track field, while the off-track field increases as well. Lamination of the pole tip is necessary for producing robust zero remanent field for deep-submicron track widths. Introducing adequate transverse anisotropy in the head will significantly shorten the relaxation time of the magnetic moments after writing with little degradation on write efficiency. [ABSTRACT FROM AUTHOR]

A three-dimensional micromagnetic model has been developed to study single pole write heads with soft magnetic underlayer (SUL) for perpendicular recording at extremely small track widths. The study points out that at any practical ABS-to-SUL spacing, the maximum head field within the recording media at deep submicron track width and pole-tip thickness becomes significantly smaller than the ideal value of 4πM[sub s]. Head field gradient in the medium also degrades with decreasing track width. Maintaining the conventional design, a significantly large remanent head field develops for track width below 100 nm, presenting danger of erasing previously recorded bits. The origin of the large remanent head field is the failure for a pole tip to reach a completely demagnetized state due to the overwhelming ferromagnetic exchange energy at the deep submicron pole-tip dimensions. [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]

In this paper, finite element method (FEM) solving Maxwell's equations is used to study writer head design with side shields. A half side shielded writer is investigated due to the belief that writer designs with larger side fringing field can be accommodated in shingled recording. It was found that although a half side shielded writer provides higher on track field, curvature at track edge is also increased. The increasing curvature poses a limit on the writer pole width increment. Designing a writer to maintain low curvature while obtaining high on-track field continues to be the challenge for shingled recording. This paper explores a full range of writer design parameters using finite element modeling and introduces several design features for a wrap-around shielded writer. [ABSTRACT FROM PUBLISHER]

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]

Wrap-around shielded writers combining both trailing shield and side shield have been studied both by modeling and by experiments. WAS design is demonstrated to have superior performance over its predecessor trailing shielded writer in perpendicular magnetic recording systems. While maintaining the down-track performance, the side shield significantly reduces the side fringing field, thus enabling high track densities. In this paper, various aspects ofWAS design are investigated. Issues unique to side shielded design such as near and far track erasure are also discussed in detail. An outlook of future PMR writer and recording systems design is presented at the end. [ABSTRACT FROM AUTHOR]

Return field-induced partial erasure (RFPE) in trailing-edge shielded perpendicular writers has been studied, both by modeling and by experiments. For a given head-media combination, the return field underneath the trailing shield increases with increasing write current. Once exceeding a certain threshold, it will cause partial erasure of the bits that have just been written by the main pole. Recording performance, such as reverse overwrite, spectral signal-to-noise ratio, and bit-error rate are all found degraded at high write currents, due to RFPE. Design optimization of both head and media together is needed, in order to maximize the advantage of a trailing-edge shielded pole head and minimize the impact of RFPE. [ABSTRACT FROM AUTHOR]

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.

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]

A computational study of the head field was presented in a specific head/media configuration, where the intermediate layer (IL) consists of the periodic magnetic columns and Ru columns. It was found that the head field increases with the thicker and wider magnetic columns. Micromagnetic simulation shows that this approach is to achieve a lower effective IL thickness for enhancing the write field by replacing some Ru grains with the columnar magnetic material without reducing the IL thickness. [ABSTRACT FROM AUTHOR]

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]

Presents a study which examined single pole perpendicular magnetic recording heads. Details of the three-dimensional micromagnetic modeling; Results; Discussion.