Abstract: A magnetoresistive (MR) sensor or read head for a magnetic recording disk drive has multiple independent current-perpendicular-to-the-plane (CPP) MR sensing elements. The sensing elements are spaced-apart in the cross-track direction and separated by an insulating separation region so as to be capable of reading data from multiple data tracks on the disk. The sensing elements have independent CPP sense currents, each of which is directed to independent data detection electronics, respectively. Each sensing element comprises a stack of layers formed on a common electrically conducting base layer, which may be a bottom magnetic shield layer formed of electrically conducting magnetically permeable material. Each sensing element has a top electrical lead layer. A top magnetic shield layer is located above the sensing elements in contact with the top lead layers.

Abstract: A magnetic write head having independent trailing and side magnetic shields. The side shields and trailing shields are independently of one another so that they can have throat heights that are different from one another. This advantageously allows the magnetic potential between the write pole and side shields to be controlled independently of one another without relying on the side gap and trailing gap thicknesses. Furthermore, magnetic performance of the write head can be improved because the side shields can be constructed with varying tapered throat heights, while the throat height of the trailing shield can remain constant.

Abstract: A hard-disk drive (HDD) with a current adjustment component is provided. The current adjustment component changes an amount of current to a magnetic-recording head of the HDD to cause a change in the strength of a magnetic write field produced by the magnetic-recording head in response to a determination that a present position of the magnetic-head head is not in a desired position. To illustrate, in response to a determination that the present position of the magnetic-recording head is further away from an edge of a current track being written than a desired position of the magnetic-recording head, the current adjustment component increases the current to the magnetic-recording head to cause an increase in the strength of the magnetic write field. The change in the strength of the magnetic write field causes data, written by the magnetic-recording head, to be located at a desired location on the magnetic-recording disk.

Abstract: A thermally-assisted perpendicular magnetic recording head and system has a head carrier that supports an optical channel for the transmission of radiation to the recording layer, a write pole for directing a magnetic field to the recording layer, and an electrical coil for inducing the magnetic field from the write pole. The optical channel has a radiation exit face with an aperture at the recording-layer-facing surface of the head carrier. The write pole has a pole tip with an end face that is recessed from the recording-layer-facing surface. The write pole tip is tapered down to the end faces. The pole tip taper and the recession of the end face concentrates the write field at the middle of the perpendicular magnetic recording layer where the radiation from the optical channel is incident. The characteristic dimension of the aperture and the spacing between the aperture and the recording layer are both less than the wavelength of the radiation.

Abstract: A method according to one embodiment comprises determining a growth rate of an erase band width between an aggressor track and a substantially unerased portion of a data track on a magnetic medium during a first number of write cycles on the aggressor track; and estimating the erase band width, or derived parameter thereof, for or after a second number of write cycles on the aggressor track, the second number of write cycles being greater than the first number of write cycles.

Abstract: A patterned perpendicular magnetic recording medium of the type that has spaced-apart pillars with magnetic material on their ends and with nonmagnetic trenches between the pillars is made with a method that allows use of a pre-etched substrate. The substrate has a generally planar surface at the trenches and comprises material that when heated will diffuse into the magnetic recording layer material and chemically react with one or more of the elements typically used in the recording layer. The pillars are formed of material that will not diffuse into the recording layer. After the recording layer is formed over the entire substrate so as to cover both the pillar ends and the trenches, the substrate is annealed. This results in the destruction or at least substantial reduction of any ferromagnetism in the recording layer material in the trenches so that the trenches are nonmagnetic.

Abstract: A write head structure for perpendicular recording having a pole tip integrated into the metal film surrounding a C aperture near field light source is disclosed. The close proximity of the pole tip to the light source enables more precise location of data cells written into the magnetic media, through the use of dual gradient thermally assisted recording. In dual gradient recording, data is fixed by the effect of both a thermal gradient, which affects the coercivity of the magnetic media, combined with a magnetic field gradient imposed by the pole tip.

Abstract: A write head structure for perpendicular recording having a pole tip integrated into the metal film surrounding a C aperture near field light source is disclosed. The close proximity of the pole tip to the light source enables more precise location of data cells written into the magnetic media, through the use of dual gradient thermally assisted recording. In dual gradient recording, data is fixed by the effect of both a thermal gradient, which affects the coercivity of the magnetic media, combined with a magnetic field gradient imposed by the pole tip.

Abstract: A method according to one embodiment comprises determining a growth rate of an erase band width between an aggressor track and a substantially unerased portion of a data track on a magnetic medium during a first number of write cycles on the aggressor track; and estimating the erase band width, or derived parameter thereof, for or after a second number of write cycles on the aggressor track, the second number of write cycles being greater than the first number of write cycles.

Abstract: A media architecture is optimized for discrete track recording. A capped or exchange-spring media uses a thin media structure and incorporates higher moment density magnetic layers. A thin exchange coupling layer is used in conjunction with a cap layer to control the reversal mechanism and exchange. Thus, the exchange coupling layer mediates the interaction between the two outer magnetic layers. The thickness of the exchange coupling layer is tuned by monitoring the media signal-to-noise ratio, track width and bit error rate. The recording performance is enhanced by tuning the intergranular exchange in the system through the use of the high-moment cap as writeability, resolution and noise are improved.

Abstract: A magnetic data recording system that can directly measure soft underlayer spacing of a perpendicular magnetic write head during operation. The soft underlayer spacing of the magnetic write head can be determined by measuring the magnetic inductance of the write head. The inductance of the write head varies with changes in the distance between the write pole and the soft underlayer of the magnetic medium. By connecting the write head with magnetic inductance measuring circuitry, the soft underlayer spacing can be constantly monitored during operation of the magnetic data recording system. The system can also include active fly height control such as a thermal fly height control capability. By directly measuring the soft underlayer spacing in real time during use of the data recording system, the actively fly height controlling features can be operated efficiently to precisely maintain a desired spacing between the write pole and the soft underlayer of the magnetic medium.

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: A magnetic data recording system that can directly measure soft underlayer spacing of a perpendicular magnetic write head during operation. The soft underlayer spacing of the magnetic write head can be determined by measuring the magnetic inductance of the write head. The inductance of the write head varies with changes in the distance between the write pole and the soft underlayer of the magnetic medium. By connecting the write head with magnetic inductance measuring circuitry, the soft underlayer spacing can be constantly monitored during operation of the magnetic data recording system. The system can also include active fly height control such as a thermal fly height control capability. By directly measuring the soft underlayer spacing in real time during use of the data recording system, the actively fly height controlling features can be operated efficiently to precisely maintain a desired spacing between the write pole and the soft underlayer of the magnetic medium.

Abstract: A magnetic write head having independent trailing and side magnetic shields. The side shields and trailing shields are independently of one another so that they can have throat heights that are different from one another. This advantageously allows the magnetic potential between the write pole and side shields to be controlled independently of one another without relying on the side gap and trailing gap thicknesses. Furthermore, magnetic performance of the write head can be improved because the side shields can be constructed with varying tapered throat heights, while the throat height of the trailing shield can remain constant.

Abstract: A write head for perpendicular magnetic recording having a write pole and first and second return poles. The write head can include a first magnetomotive force source for delivering a magnetomotive force to the first return pole and the write pole and a second magnetomotive force source for delivering magnetomotive force to the second return pole and the write pole. The first and second magnetomotive force sources can be operated independently of one another so that different relative amounts of magnetomotive force can be applied to the first and second return poles.

Abstract: A patterned perpendicular magnetic recording medium of the type that has spaced-apart pillars with magnetic material on their ends and with nonmagnetic trenches between the pillars is made with a method that allows use of a pre-etched substrate. The substrate has a generally planar surface at the trenches and comprises material that when heated will diffuse into the magnetic recording layer material and chemically react with one or more of the elements typically used in the recording layer. The pillars are formed of material that will not diffuse into the recording layer. After the recording layer is formed over the entire substrate so as to cover both the pillar ends and the trenches, the substrate is annealed. This results in the destruction or at least substantial reduction of any ferromagnetism in the recording layer material in the trenches so that the trenches are nonmagnetic.

Abstract: A thermally-assisted perpendicular magnetic recording head and system has a head carrier that supports an optical channel for the transmission of radiation to the recording layer, a write pole for directing a magnetic field to the recording layer, and an electrical coil for inducing the magnetic field from the write pole. The optical channel has a radiation exit face with an aperture at the recording-layer-facing surface of the head carrier. The write pole has a pole tip with an end face that is recessed from the recording-layer-facing surface. The write pole tip is tapered down to the end faces. The pole tip taper and the recession of the end face concentrates the write field at the middle of the perpendicular magnetic recording layer where the radiation from the optical channel is incident. The characteristic dimension of the aperture and the spacing between the aperture and the recording layer are both less than the wavelength of the radiation.

Abstract: A method for estimating the average intergranular exchange field using measurements of major and minor hysteresis loops. The method also facilitates deshearing hysteresis loops for analysis purposes in perpendicular media. This estimation technique is especially important for modern perpendicular media because exchange plays a critical role and process control can be difficult.