Abstract: The various implementations described herein include methods, devices, and systems for fabricating magnetic memory devices. In one aspect, a method of fabricating a magnetic memory device includes: (1) providing a dielectric substrate with a metallic core protruding from the dielectric substrate, where: (a) a first portion of the metallic core is surrounded by the dielectric substrate and a second portion of the metallic core protrudes away from a surface of the dielectric substrate; and (b) the second portion includes: (i) a surface offset from the surface of the dielectric substrate and (ii) sidewalls extending away from the surface of the dielectric substrate to the offset surface; (2) depositing a first ferromagnetic layer on exposed surfaces of the metallic core and the dielectric substrate; (3) depositing a spacer layer on exposed surfaces of the first ferromagnetic layer; and (4) depositing a second ferromagnetic layer on exposed surfaces of the spacer layer.

Abstract: A magnetic memory device is provided. The magnetic memory device includes: (i) a cylindrical core, (ii) a first cylindrical ferromagnetic layer that surrounds the cylindrical core, (iii) a spacer layer that surrounds the first cylindrical ferromagnetic layer, and (iv) a second cylindrical ferromagnetic layer that surrounds the spacer layer. The cylindrical core, the first cylindrical ferromagnetic layer, the spacer layer, and the second cylindrical ferromagnetic layer collectively form a magnetic tunnel junction.

Abstract: The various embodiments described herein include methods, devices, and systems for fabricating and performing operations on magnetic memory devices. In one aspect, a magnetic memory device includes: (1) a reference magnetic layer configured to have a first current threshold corresponding to a spin current level required to change a magnetic polarization of the reference magnetic layer; (2) a composite magnetic layer comprising a plurality of non-magnetic layers and a plurality of magnetic layers including a storage layer; and (3) a non-magnetic spacer layer between the reference magnetic layer and the composite magnetic layer; where the composite magnetic layer is configured such that the second current threshold is lowered, without decreasing thermal stability of the magnetic memory device, by spin current and/or coupling fields between adjacent magnetic layers of the plurality of magnetic layers.

Abstract: The various implementations described herein include methods, devices, and systems for fabricating magnetic memory devices. In one aspect, a method of fabricating a magnetic memory device includes: (1) providing a dielectric substrate with a metallic core protruding from the dielectric substrate, where: (a) a first portion of the metallic core is surrounded by the dielectric substrate and a second portion of the metallic core protrudes away from a surface of the dielectric substrate; and (b) the second portion includes: (i) a surface offset from the surface of the dielectric substrate and (ii) sidewalls extending away from the surface of the dielectric substrate to the offset surface; (2) depositing a first ferromagnetic layer on exposed surfaces of the metallic core and the dielectric substrate; (3) depositing a spacer layer on exposed surfaces of the first ferromagnetic layer; and (4) depositing a second ferromagnetic layer on exposed surfaces of the spacer layer.

Abstract: A magnetic memory device is provided. The magnetic memory device includes: (i) a cylindrical core, (ii) a first cylindrical ferromagnetic layer that surrounds the cylindrical core, (iii) a spacer layer that surrounds the first cylindrical ferromagnetic layer, and (iv) a second cylindrical ferromagnetic layer that surrounds the spacer layer. The cylindrical core, the first cylindrical ferromagnetic layer, the spacer layer, and the second cylindrical ferromagnetic layer collectively form a magnetic tunnel junction.

Abstract: The various embodiments described herein include methods, devices, and systems for fabricating and performing operations on magnetic memory devices. In one aspect, a magnetic memory device includes: (1) a reference magnetic layer configured to have a first current threshold corresponding to a spin current level required to change a magnetic polarization of the reference magnetic layer; (2) a composite magnetic layer comprising a plurality of non-magnetic layers and a plurality of magnetic layers including a storage layer; and (3) a non-magnetic spacer layer between the reference magnetic layer and the composite magnetic layer; where the composite magnetic layer is configured such that the second current threshold is lowered, without decreasing thermal stability of the magnetic memory device, by spin current and/or coupling fields between adjacent magnetic layers of the plurality of magnetic layers.

Abstract: A Magnetic Random Access Memory (MRAM) structure having a thermally conductive, dielectric cladding material that contacts an outer side of a magnetic memory element. The magnetic memory element can be a magnetic tunnel junction element formed as a cylindrical pillar that extends between first and second electrically conductive lead layers. The cylinder of the magnetic memory element can have an outer periphery, and the cladding material can be formed to contact the entire periphery. In addition, a heat sink structure formed of a dielectric material having a high specific heat capacity can be formed to contact an outer periphery of the cladding material. The cladding material and heat sink structure efficiently conduct heat away from the sides of the memory element to prevent the temperature of the memory element to rise to unsafe levels. This advantageously assists in maintaining a high reliability and long life of the MRAM system.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks, each track comprising a plurality of data sectors. A circular buffer is defined comprising a plurality of the tracks. During a garbage collection operation, write data is read from previously written valid data sectors corresponding to a tail of the circular buffer and stored in a non-volatile cache. During a flush operation, the write data is flushed from the non-volatile cache to the disk.

Abstract: Adaptively determining shingle guard band widths on at least one disk of a data storage device (DSD). The at least one disk includes a plurality of zones of shingle tracks for storing data. At least one of a magnetic erase width (MEW) and a magnetic read width (MRW) are measured and a shingle track pitch (STP) is determined. The shingle guard band width is determined based at least partly on the STP and at least one of the MEW or the MRW.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, wherein the head comprises a laser operable to heat the disk while writing data to the disk, and a fly height actuator (FHA) operable to adjust a fly height of the head over the disk. When a write command is received to write data to a target data track, the head is positioned over the target data track. When the head approaches a target data sector of the target data track, a power applied to the FHA is increased to decrease the fly height of the head. When the head reaches the target data sector, a power applied to the laser is increased to heat the disk, and the power applied to the FHA is decreased substantially monotonically while writing data to the target data sector.

Abstract: A read system for a hard disk drive comprising a disk having magnetic fields. The read system comprises a read element, a bias source, a temperature sensor, and a controller. The resistance of the read element changes based on the magnetic fields. The bias source applies a bias level to the read element. The temperature sensor generates a temperature signal indicative of a head ambient temperature. The controller adapts the bias level based on the temperature signal.

Abstract: In one example, a method is provided and includes comparing a measured change in spacing between a transducer element and a storage element in response to a fly height control signal with an expected change in spacing for the applied fly height control signal. The method also includes detecting an event condition based on the comparison between the measured change in spacing and the expected change in spacing.

Abstract: Detection of contact between a sensor, such as a data head or a slider, and a surface, such as the magnetic surface of a disk is achieved using the efficiency of actuator associated with the sensor. In this manner, the fly height of the sensor can be calibrated substantially continuously.

Abstract: A hard disk is provided with tools for limiting the duty cycle (a group of variations of load with time). The write current is controlled by, e.g., limiting the duration of a given write cycle. The write cycle may involve writing data continuously along adjacent portions of the disk media (e.g., writing of data in adjacent segments of a track in the outer diameter (OD) region of a platter), with an intermittent duty write current.