Abstract: A combined bulk thermal-assister and bulk eraser. The bulk thermal-assister is configured to produce a temperature in a magnetic-recording disk in a hard-disk drive when the hard-disk drive is disposed in the bulk eraser. The temperature is about equal to a second temperature greater than a first temperature of the magnetic-recording disk. The bulk eraser is configured to erase recorded information from the magnetic-recording disk at the second temperature.

Abstract: A combined bulk thermal-assister and bulk eraser. The bulk thermal-assister is configured to produce a temperature in a magnetic-recording disk in a hard-disk drive when the hard-disk drive is disposed in the bulk eraser. The temperature is about equal to a second temperature greater than a first temperature of the magnetic-recording disk. The bulk eraser is configured to erase recorded information from the magnetic-recording disk at the second temperature.

Abstract: A perpendicular magnetic recording data storage system combines a perpendicular medium that has a thin low-magnetic-permeability or “soft” underlayer (SUL) with a recording head that has a trailing shield (TS) with a thick throat height, i.e., a thickness in a direction orthogonal to the recording layer of the medium. The SUL is thin enough and has a low enough magnetic permeability to become saturated in a region beneath the trailing gap of the head during writing, but the throat height of the TS is thick enough to prevent the TS from becoming magnetically saturated during writing. The magnetic saturation of the SUL during writing changes the magnetic reluctance such that more of the magnetic flux going through the SUL changes direction (“field undershoot”) and goes to the TS. If the permeability of the SUL is so low (e.g.

Abstract: An apparatus, system, and method are disclosed for writing magnetically encoded data. A servo module positions a write head relative to a first land such that a first edge of the write head is positioned substantially over a first land edge of the first land. The write head has a radial width greater than the sum of a radial width of the first land and radial widths of interior and exterior grooves such that the write head is also positioned over at least a portion of a second adjacent land. The write head writes magnetically encoded data to the first land. The servo module further positions the write head relative to a second land such that the first edge of the write head is positioned substantially over a second land edge of the second land and the write head is not positioned over the first land.

Abstract: A perpendicular magnetic recording medium has an “exchange-spring” type magnetic recording layer (RL) formed of two ferromagnetic layers with substantially similar anisotropy fields that are ferromagnetically exchange-coupled by a nonmagnetic or weakly ferromagnetic coupling layer. Because the write head produces a larger magnetic field and larger field gradient at the upper portion of the RL, while the field strength decreases further inside the RL, the upper ferromagnetic layer can have a high anisotropy field. The high field and field gradient near the top of the RL, where the upper ferromagnetic layer is located, reverses the magnetization of the upper ferromagnetic layer, which then assists in the magnetization reversal of the lower ferromagnetic layer. Because both ferromagnetic layers in this exchange-spring type RL have a high anisotropy field, the thermal stability of the medium is not compromised. The medium shows improved writability, i.e.

Abstract: A magnetic write head for perpendicular magnetic recording, the write head having a magnetic write pole configured with a cross section as viewed from the ABS that has a trailing portion with substantially vertical side walls and a leading portion formed with a taper that becomes narrower as it extends toward the leading edge. The write pole provides for excellent write field strength by providing sufficient cross section near the trailing edge to avoid magnetic saturation of the pole tip. The parallel side walls of the trailing portion also provide for excellent track width control during manufacture of the write head. The tapered portion of the write head, which starts some distance away from the trailing edge, prevents skew related adjacent track writing when the actuator that holds the write head is at its innermost or outermost travel extensions.

Abstract: A perpendicular magnetic recording disk has an antiferromagnetically-coupled (AFC) recording layer (RL) comprised of lower and upper ferromagnetic layers, each having a hexagonal-close-packed (hcp) crystalline structure and perpendicular magnetic anisotropy, separated by an antiferromagnetically (AF) coupling layer, wherein the lower ferromagnetic layer (LFM) has substantially higher magnetic permeability than the upper ferromagnetic layer (UFM). The AFC RL is located on an actual exchange break layer (EBL) that separates the AFC RL from the disk's soft magnetic underlayer (SUL). The LFM functions as part of an “effective” exchange break layer (EBL) that also includes the actual EBL and the AF-coupling layer, thereby allowing the actual EBL to be made as thin as possible. The hcp LFM promotes the growth of the hcp UFM in the same way the actual EBL does so that its thickness contributes to the thickness necessary to grow the hcp UFM.

Abstract: The invention uses an upper and lower magnetic layer of a laminated magnetic layer structure that includes an AF spacer layer that results in weak antiferromagnetic coupling of the magnetic layers that is insufficient to cause either of the layers to switch so that the magnetic orientations of the two ferromagnetic layers remain parallel. An advantage of the invention is that the AF-coupling tends to anti-correlate the noise in the two layers. The weak AF coupling according to the invention is believed to act at the transition boundaries in the media to cause some of the noise domains to be oriented antiparallel and the noise to be less correlated than would be the case without the AF coupling and thereby to achieve improved SNR.