Write Margin Improvement in Bit Patterned Media With Inclined Anisotropy at High Areal Densities

Abstract

Bit patterned media with inclined anisotropy were proposed along with media design with a higher saturation magnetization and a small thickness for the dot. Inclination of the anisotropy axis was found to reduce broadened switching field distribution of the media caused by the magnetostatic interaction between the dots. Recording simulation at an areal density of 2.6 Tbit/in 2 using a write field of a shielded planar head exhibited substantially increased write shift margins of 6.5 nm and 10 nm in down-and cross track directions, respectively, for the media with inclined anisotropy when the anisotropy dispersion of the media was as small as 2%. Recording density was expected to be increased beyond 4 Tbit/in 2 for the media with additional exchange coupling between the dots.Index Terms-Bit patterned media, inclined anisotropy, shielded planar head, write margin.

Feasibility of Bit Patterned Magnetic Recording With Microwave Assistance Over 5 Tbitps

“…For an FGL with magnetization rotational FGL in plane, the effective perpendicular magnetic anisotropy needs a smaller value than 4 kOe. A planar magnetic anisotropy material such as [11] is indispensable at FGL of STO for areal recording density over 5 . To obtain efficiency of the microwave assisted magnetization switching by high-frequency magnetic fields to be generated from the FGL, an effective high-frequency magnetic field component is determined.…”

“…However, the value of 25 nm for the full width of half maximum of the effective high-frequency field seems to be too large and might disturb the magnetization of a neighboring bit at writing. It seems difficult for the high-frequency magnetic field from FGL alone to obtain a required track density for over 5 . Thus we should decide to use narrow main pole and superpose the field gradients of main pole and FGL in the cross track direction.…”

“…The two-spin model was investigated to analyze oscillation feature of a particular STO for areal recording density over 5 . To obtain both a narrower track width and larger highfrequency field for the areal recording density, a 15 nm-cubic FGL was assumed (Fig.…”

“…In this work, we used a micromagnetic simulation to investigate the possibility of an MAMR with a high-frequency field from a narrow FGL on bit-patterned media (BPM) over 5 .…”

Read-head Conditions for Obtaining Areal Recording Density of 5.8 Tbit/in.2 on a Bit-Patterned Medium

“…A conceptually straightforward solution for the thermal-stability problem at high areal density is to define individual bits as continuous single-domain entities with a relatively large volume. A ''bit-patterned medium'' (BPM) [18][19][20][21][22] is a promising technology for obtaining an areal recording density of more than 5 Tbit/in. 2 .…”