Suping Song

Finite Element Analysis of Alternating Write-Current-Induced Pole Tip Protrusion in Magnetic Recording Heads

This paper presents a finite element analysis of alternating write-current-induced pole tip protrusion (WPTP) generated in longitudinal magnetic recording (LMR) heads. An integrated magneto-thermal-mechanical model is developed for the simulations of the electromagnetic Joule heating generated in the LMR writer, the slider temperature distribution, and the slider deformation during writing. The computed results are compared with the experimental measurements in terms of writer resistance and inductance, the WPTP, and temperature rise at reader location. It is found that eddy currents are strongly induced near the surfaces of write poles, while the eddy currents induced in write coils are negligibly weak. The results show that the eddy current loss in the write poles dominates over the Joule heat generated in the write coils. It is also found that the maximum protrusion appears near the write pole in the overcoat and the protrusion profile is sharper than that induced by equivalent direct write current and coil resistance

Micromagnetic Analysis of Adjacent Track Erasure of Wrapped-Around Shielded PMR Writers

This paper presents a numerical analysis of adjacent track erasure (ATE) when operating wrapped-around shielded perpendicular magnetic recording (PMR) heads. Micromagnetic finite element modeling was used to investigate the magnetization dynamics in a PMR writer including a soft underlayer, and the resultant magnetic field in the recording layer. It is found that the ATE-field is an asymmetric and localized return field. Such an asymmetry is determined by the directions of both the magnetization in the pole tip and the initial magnetization in the WAS. The ATE-field is located near the corner and the inner edge of one side-shield. It is also found that the ATE-field remains strong for most of the time during write-field switching.

Pole tip protrusion of giant magnetic recording heads: Simulation and experimental verification

This paper presents an integrated finite element modeling of the pole tip protrusion (PTP) of giant magnetic recording heads during writing operation. The convection heat transfer models are presented in detail and verified by Guzik measurements. Modeling results agree well with the measurements in terms of the protrusion and the temperature rise at reader. It is found that the second shield (S2) protrudes the most regardless of the presence or absence of the airflow such as induced by a spinning disk. It is also found that the viscous dissipation generated in air bearing gives a negligible impact on the PTP.

A comparative study of alternating write-current-induced pole tip protrusion in perpendicular and longitudinal recording heads

This paper presents a comparative study of alternating write-current-induced pole tip protrusions (WPTP) in perpendicular magnetic recording (PMR) and longitudinal magnetic recording (LMR) heads during writing operation. Both finite element modeling and experimental measurements were performed for this study. The results show that the writer resistance and inductance as well as the WPTP of PMR heads are all substantially lower than those of LMR heads within the write-current frequency range under consideration. It is found that the WPTP of a LMR head is mainly attributed to the eddy-current-induced Joule heating in yoke, whereas for a PMR head, the contribution to the WPTP from the Joule heating generated in write coils is comparable to that induced in yoke.

Micromagnetic Study of Short and Long Yoke PMR Head With Trailing Shield

The response of a trailing shielded perpendicular magnetic recording (PMR) write head with a three-turn two-layer coils is calculated using a full micromagnetic large scale model including return pole and soft underlayer. We study the effect of PMR yoke length and write current overshoot on the dynamic response of the head at high frequency. In particular, recording performance parameter, nonlinear transition shift (NLTS) is simulated using micromagnetic media model. Shorter yoke length head improves NLTS as compared with longer yoke length. Measured NLTS has qualitative agreement with micromagnetic model results.

Finite-Element Analysis of Stress Induced Magnetic Anisotropy in Perpendicular Writers

This paper presents finite-element analysis of the stress-induced magnetic anisotropy in perpendicular magnetic recording (PMR) heads developed during fabrication. The intrinsic stresses of various thin films used in the heads were measured using wafer curvature, while the stress in the yoke region was measured using X-ray diffraction. The measured stresses are provided. The initial strains due to the intrinsic stresses in the films were modeled using equivalent thermal strains and the calculations were verified by correlations with the stress measurements. Finite-element simulations were performed for calculating the stresses in full PMR heads. Detailed simulation procedures are described. Computed results are presented on how sensitive the magnetic anisotropy in the write pole are to the pole tip length and the slider lapping and the compressive stress in overcoat as well as the ambient temperature