Abstract: A patterned perpendicular magnetic recording disk with discrete data islands of recording layer (RL) material includes a substrate, a patterned exchange bridge layer of magnetic material between the substrate and the islands, and an optional exchange-coupling control layer (CCL) between the exchange bridge layer and the islands. The exchange bridge layer has patterned pedestals below the islands. The exchange bridge layer controls exchange interactions between the RLs in adjacent islands to compensate the dipolar fields between islands, and the pedestals concentrate the flux from the write head. The disk may include a soft underlayer (SUL) of soft magnetically permeable material on the substrate and a nonmagnetic exchange break layer (EBL) on the SUL between the SUL and the exchange bridge layer. In a thermally-assisted recording (TAR) disk a heat sink layer may be located below the exchange bridge layer and the SUL may be optional.

Abstract: A thermally-assisted recording (TAR) bit-patterned-media (BPM) magnetic recording disk drive uses optical detection of synchronization fields for write synchronization and optical detection of servo sectors for read/write head positioning. The synchronization fields and servo sectors extend generally radially across the data tracks and are patterned into discrete nondata blocks separated by gaps in the along-the-track direction. A near-field transducer (NFT) directs laser radiation to the disk and generates a power absorption profile on the disk that has a characteristic along-the-track spot size less than the along-the-track length of the gaps between the nondata blocks in the synchronization fields and servo sectors.

Abstract: A perpendicular magnetic recording system has a write head with a main perpendicular write pole connected to a yoke with first and second electrical coils. The first coil is wrapped around the yoke on one side of the main pole, and the second coil is wrapped around the yoke on the other side of the main pole. The first end of each coil is connected to a respective terminal. The second ends of the two coils are connected together and connected to a common terminal. A lead-time circuit is connected between the common terminal and the first end of one of the coils. Immediately after the direction of write current is switched by the write driver, the lead-time circuit causes the current in one of the coils to lead the current in the other coil. The current displacement between the two coils creates a precession of the magnetic flux reversal, thereby reducing the switching time of the write head.

Abstract: A current-perpendicular-to-the-plane magnetoresistive (CPP MR) sensor has a shield layers that also functions as the sensor's reference layer. In a CPP MR disk drive read head, the shield layer has a fixed magnetization oriented substantially parallel to the air-bearing surface (ABS) of the slider that supports the read head. The quiescent magnetization of the sensor free layer is oriented at an angle relative to the magnetization of the shield layer, preferably between 120 and 150 degrees, to optimize the sensor response to magnetic fields from the recorded data bits on the disk. The magnetization of the free layer is biased by a biasing structure that includes a ferromagnetic side biasing layer formed near the side edges of the free layer and a ferromagnetic back biasing layer that is recessed from the ABS and has a magnetization oriented generally orthogonal to the ABS.

Abstract: A perpendicular magnetic recording system has a write head having a main coil (the write coil) and main pole (the write pole) that directs write flux in a direction perpendicular to the recording layer in the magnetic recording medium, and an auxiliary coil and auxiliary pole that injects magnetic flux into the write pole at an angle to the primary or perpendicular axis of the write pole. The additional flux from the auxiliary pole, which is injected non-parallel to the primary magnetization of the write pole, exerts a relatively large torque on the magnetization of the write pole, thereby facilitating magnetization reversal of the write pole. Electrical circuitry is connected to the main coil and the auxiliary coil to generate the auxiliary flux simultaneous with the switching of the magnetization of the write pole.

Abstract: A perpendicular magnetic recording system has a write head having a main helical coil (the write coil) and main pole (the write pole) that directs write flux in a direction perpendicular to the recording layer in the magnetic recording medium, and an auxiliary coil and auxiliary pole that injects magnetic flux into the write pole at an angle to the primary or perpendicular axis of the write pole. The auxiliary coil is preferably a helical coil wrapped around the auxiliary pole. The additional flux from the auxiliary pole, which is injected non-parallel to the primary magnetization of the write pole, exerts a relatively large torque on the magnetization of the write pole, thereby facilitating magnetization reversal of the write pole. Electrical circuitry is connected to the main coil and the auxiliary coil to generate the auxiliary flux simultaneous with the switching of the magnetization of the write pole.

Abstract: A write head and a method for forming the write head. The method includes providing a first pole and a second pole for the write head. The first pole and the second pole are formed from a ferromagnetic material. Regions of the write head including at least a portion of at least one of the first pole and the second pole of the write head are volumetrically doped with a dopant material selected from one of a 4d transition metal, 5d transition metal, and 4f rare earth metal. The dopant material is predetermined to provide a magnetic damping in the doped regions which is greater than the magnetic damping in the ferromagnetic material.

Abstract: A magnetic head having a magnetic wiggler structure for initiating a high frequency magnetic oscillation in a magnetic to improve media-writeability and increase data density. The wiggler structure includes a plurality of magnetic layers that are antiparallel coupled with one another across non-magnetic antiparallel coupling layers. The wiggler structure is arranged just up-track from the point of data writing so that the high frequency oscillation is initiated just prior to the writing of data on the magnetic media.

Abstract: Compression methods and systems that encode the bounding volume hierarchy (BVH) and the triangles of a scene in one compact data structure. Efficient on-the-fly decompression is performed and may be used in interactive ray tracing. Quantized vertices and triangle strips may be stored in BVH leaf nodes. The local vertex positions and vertex indices may use a small number of bits that are encoded in bit strings. During traversal, the geometry may be decoded by an optimized algorithm allowing for random access with minimal overhead.

Abstract: A perpendicular magnetic recording system has a write head having a main coil (the write coil) and main pole (the write pole) that directs write flux in a direction perpendicular to the recording layer in the magnetic recording medium, and a transverse auxiliary pole (TAP) that injects auxiliary magnetic flux into the write pole at an angle to the primary or perpendicular axis of the write pole. The additional flux from the TAP, which is injected non-parallel to the primary magnetization of the write pole, exerts a torque on the magnetization of the write pole, thereby facilitating magnetization reversal of the write pole. The TAP is coupled to the main coil but not electrically connected to it. A separate passive coil, not electrically connected to the main coil, may be wrapped as a loop around the main pole and the TAP. Alternatively, the TAP may be located near one of the electrically conductive turns of the main coil.

Abstract: A perpendicular magnetic recording hard disk drive includes a write head with a write pole and an electrically conductive coil coupled to the write pole, a write driver for supplying electrical write current to the coil to generate magnetic flux in the write pole, a spin torque oscillator (STO) that injects auxiliary magnetic flux to the write pole to facilitate magnetization switching of the write pole, and STO control circuitry. Direct electrical current to the STO induces rotation of the magnetization of a free ferromagnetic layer in the STO, which generates the auxiliary magnetic flux. The STO control circuitry may be coupled to the STO via the electrical lines that connect the write driver to the write head, the lines that connect the read amplifier to the read head, or, if the disk drive is one with thermal fly-height control (TFC), the lines that connect the TFC circuitry with the heater.

Abstract: A perpendicular magnetic recording write head that a write pole, an electrically conductive coil coupled to the write pole for generating magnetic flux in the write pole in the presence of electrical write current, and a spin torque oscillator (STO) that injects auxiliary magnetic flux to the write pole in a direction generally orthogonal to the write pole to facilitate magnetization switching of the write pole. The STO comprises a stack of layers including electrodes, a pinned ferromagnetic layer having a fixed, a free ferromagnetic layer having a magnetization free to rotate, and a nonmagnetic spacer layer between the pinned and free layers. The free layer may be oriented either substantially orthogonal to the write pole or substantially parallel to the write pole, in which latter embodiment a flux guide may be located between the free layer and the write pole for directing the auxiliary magnetic flux from the free layer to the write pole.

Abstract: A patterned-media magnetic recording disk drive uses an optical system for accurately clocking the write data. The disk has concentric data tracks patterned into discrete magnetizable data islands with nonmagnetic spaces between the islands. As the disk rotates, a radiation source directs near-field radiation to the islands and spaces, and a radiation detector receives reflected radiation. The radiation is directed from the source through an optical channel or waveguide on the air-bearing slider that supports the read and write heads. The optical channel or waveguide has a near-field transducer at the disk-facing surface of the slider where the near-field radiation exits and reflected radiation returns. The reflected optical power varies depending on whether the near-field transducer couples to an island or a space, so the radiation detector output signal represents the frequency and phase of the islands as the disk rotates.

Abstract: A patterned-media magnetic recording disk drive has compensation for write head track misregistration (TMR) from the track centerline. As the disk rotates, the read head detects angularly spaced servo sectors and generates a position error signal (PES) which is used by the servo control system to maintain the read head on track. As the disk rotates, the read head also detects angularly spaced synchronization marks, which are used to control the write clock so that magnetization reversal of the magnetic write field from the write head is synchronized with the position of the data islands. If there is TMR of the write head, there will be an effective shift of A(p in the timing of when the center of the data islands pass through the write field. The disk drive includes write clock phase adjustment circuitry that correlates the PES with ?? to compensate for TMR of the write head.

Abstract: A patterned-media magnetic recording disk drive has compensation for write head track misregistration (TMR) from the track centerline. As the disk rotates, the read head detects angularly spaced servo sectors and generates a position error signal (PES) which is used by the servo control system to maintain the read head on track. As the disk rotates, the read head also detects angularly spaced synchronization marks, which are used to control the write clock so that magnetization reversal of the magnetic write field from the write head is synchronized with the position of the data islands. If there is TMR of the write head, there will be an effective shift of ?? in the timing of when the center of the data islands pass through the write field. The disk drive includes write clock phase adjustment circuitry that correlates the PES with ?? to compensate for TMR of the write head.

Abstract: A perpendicular magnetic recording system has a write head having a main coil (the write coil) and main pole (the write pole) that directs write flux in a direction perpendicular to the recording layer in the magnetic recording medium, and an auxiliary coil and auxiliary pole that injects magnetic flux into the write pole at an angle to the primary or perpendicular axis of the write pole. The additional flux from the auxiliary pole, which is injected non-parallel to the primary magnetization of the write pole, exerts a relatively large torque on the magnetization of the write pole, thereby facilitating magnetization reversal of the write pole. Electrical circuitry is connected to the main coil and the auxiliary coil to generate the auxiliary flux simultaneous with the switching of the magnetization of the write pole.

Abstract: A perpendicular magnetic recording system has a write head having a main helical coil (the write coil) and main pole (the write pole) that directs write flux in a direction perpendicular to the recording layer in the magnetic recording medium, and an auxiliary coil and auxiliary pole that injects magnetic flux into the write pole at an angle to the primary or perpendicular axis of the write pole. The auxiliary coil is preferably a helical coil wrapped around the auxiliary pole. The additional flux from the auxiliary pole, which is injected non-parallel to the primary magnetization of the write pole, exerts a relatively large torque on the magnetization of the write pole, thereby facilitating magnetization reversal of the write pole. Electrical circuitry is connected to the main coil and the auxiliary coil to generate the auxiliary flux simultaneous with the switching of the magnetization of the write pole.

Abstract: Multiple anisotropy layered magnetic structures for controlling reversal mechanism and tightening of switching field distribution in bit patterned media are disclosed. The invention extends the exchange spring concept to more variable and sophisticated structures. Three or more layers with different anisotropy or anisotropy gradients increase writeability gains beyond the simple hard/soft bilayer exchange spring concept for BPM. The structures have a thin very hard, high anisotropy center layer that acts as a threshold or pinning layer for domain wall propagation through the entire media structure. In addition or alternatively, a thin very soft, low anisotropy center layer in between the commonly used soft surface layer and hard media layer allows quick initial propagation of the domain wall into the center of the media structure. Various properties of the media structures can be tuned more independently for optimization if using more advanced multi-anisotropy layer stacks.

Abstract: A patterned-media magnetic recording disk drive uses an optical system for clocking the write data and a patterned-media disk that has discrete magnetizable data islands with nonmagnetic spaces between the islands, wherein the nonmagnetic spaces contain optical contrast material. The optical contrast material may be optically absorptive material, fluorescent material, or a metal layer that generates surface plasmons when excited by radiation of a specific wavelength. Radiation from a primary radiation source is directed to a near-field transducer maintained near the disk surface and a radiation detector detects radiation reflected back from the transducer. If the disk has fluorescent material or a metal layer in the nonmagnetic spaces, then a secondary radiation source irradiates the fluorescent material or metal layer with radiation of a specific wavelength to cause the fluorescent material to emit radiation or the metal layer to generate surface plasmons.

Abstract: A perpendicular magnetic recording system has a write head with a main perpendicular write pole connected to a yoke with first and second electrical coils. The first coil is wrapped around the yoke on one side of the main pole, and the second coil is wrapped around the yoke on the other side of the main pole. The first end of each coil is connected to a respective terminal. The second ends of the two coils are connected together and connected to a common terminal. A lead-time circuit is connected between the common terminal and the first end of one of the coils. Immediately after the direction of write current is switched by the write driver, the lead-time circuit causes the current in one of the coils to lead the current in the other coil. The current displacement between the two coils creates a precession of the magnetic flux reversal, thereby reducing the switching time of the write head.