Abstract: A heat-assisted magnetic recording (HAMR) write head has a write pole with a chemically-passivated end that substantially prevents oxidation and thus improves corrosion resistance of the write pole. The write pole and near-field transducer (NFT) are supported on a slider and have their ends in a window region of the slider's disk-facing surface. The outer surface region of the write pole is chemically-passivated, preferably by exposure to a nitrogen plasma. The nitrogen plasma has no effect on the NFT end or on the magnetoresistive read head, which is protected because it is located in a non-window region of the slider's disk-facing surface. An optically transparent protective film is formed in the window over the passivated write pole end and NFT end.

Abstract: According to one embodiment, a magnetic disk device includes: a disk; a head including a main magnetic pole, a write shield that faces the main magnetic pole in a first direction and is separated from the main magnetic pole by a gap, a first assist element that is disposed in the gap and a second assist element that is disposed in the gap and is positioned relative to the first assist element in a second direction intersecting the first direction; and a controller configured to: cause a first assist energy from the first assist element to be applied to the disk and affect a coercive force of the disk; and cause a second assist energy from the second assist element to be applied to the disk and affect a coercive force of the disk, wherein the first assist energy is different from the second assist energy.

Abstract: A recording head includes a near-field transducer proximate a media-facing surface of the recording head and a waveguide that overlaps and delivers light to the near-field transducer. The recording head includes subwavelength-sized focusing mirror comprising first and second reflectors disposed on cross track sides of the near-field transducer. Each of the first and second reflectors is spaced apart from the media-facing surface by a distance, D, measured along an axis normal to the media-facing surface.

Abstract: An apparatus comprises a slider configured to facilitate heat assisted magnetic recording and a submount affixed to the slider. A laser unit is affixed to the submount and comprises a laser operable in a non-lasing state and a lasing state. A heater is embedded in the laser unit or the submount. The heater is configured to generate preheat for heating the laser during the non-lasing state and to generate steering heat for heating the laser during the lasing state.

Abstract: The present disclosure describes aspects of pulse-based writing for magnetic storage media. In some aspects, a pulse-based writer of magnetic storage media determines that a string of data bits having a same polarity corresponds to a magnet longer than a threshold associated with a magnetic media writer. The pulse-based writer inserts, into the string of data bits, a transition to a polarity opposite to the same polarity of the string of data bits. The string of data bits including the inserted transition is then transmitted to the magnetic media writer to cause a write head of the writer to pulse while writing the magnet to magnetic storage media. Various aspects may also implement a control signal to mask a transition or control polarity of the magnetic media writer. By so doing, magnets may be written to the magnetic storage media more efficiently or with less distortion to neighboring tracks.

Abstract: A thermally assisted magnetic head including a slider and a light source-unit. The slider includes a slider substrate and a magnetic head part. The light source-unit includes a laser diode and a sub-mount. The magnetic head part includes a medium-opposing surface, a light source-opposing surface and a waveguide which guides laser light from the light source-opposing surface to the medium-opposing surface. The slider substrate includes a light source-cavity formed in a light source-placing surface on which the light source-unit is placed. The light source-cavity includes an opening concave part being formed larger than a mount bottom surface of the sub-mount. The mount bottom surface of the sub-mount is inserted into the opening concave part to be joined to the light source-cavity.

Abstract: A microwave-assisted magnetic recording (MAMR) write head has a spin-torque oscillator (STO) and a ferromagnetic compensation layer between the write pole and trailing shield. The compensation layer is separated from a free layer by a nonmagnetic barrier layer that prevents spin-polarized electrons from the free layer from reaching the compensation layer. The compensation layer may be located between the write pole and the free layer. Electrons become spin-polarized by the compensation layer and are reflected back from the write pole across a nonmagnetic spacer layer. This causes the magnetization of the compensation layer to flip and become antiparallel to the magnetization of the free layer. The compensation layer thus generates a DC offset field that compensates for the negative effect of the DC shunting field from the free layer.

Abstract: A spin transfer torque (STT) device is formed on an electrically conductive substrate and includes a ferromagnetic polarizer layer near the substrate, a ferromagnetic free layer, and a nonmagnetic spacer layer between the ferromagnetic polarizer layer and the ferromagnetic free layer. A multilayer structure is located between the substrate and the ferromagnetic polarizer layer. The multilayer structure includes a metal or metal alloy seed layer for the ferromagnetic polarizer layer and an intermediate oxide layer below and in contact with the seed layer. The intermediate oxide layer reflects spin current from the write pole and thus reduces undesirable spin pumping of the ferromagnetic polarizer layer.

Abstract: A method includes generating, during manufacture of a heat-assisted magnetic recording (HAMR) disk drive, a temperature compensation equation for a compensation factor using initial operating currents supplied to a laser diode of the disk drive at different initial operating temperatures and an efficiency value based on the initial operating temperatures. The operating currents are representative of currents for recording data to or erasing data from a magnetic recording medium. The temperature compensation equation is stored in the disk drive. A subsequent efficiency value is determined based on at least one of the initial operating temperatures and an operating temperature differing from the initial operating temperatures. An updated compensation factor at the operating temperature is determined during field operation using the temperature compensation equation and the subsequent efficiency value. An updated operating current is calculated using the updated compensation factor and the operating temperature.

Abstract: According to one embodiment, a magnetic recording apparatus measures and stores recording signal quality of a disk at an initial stage, inspects the recording signal quality before data is recorded, determines whether or not the recording signal quality obtained in the inspection satisfies a standard when compared to the stored recording signal quality at the initial stage, adjusts, based on a result of the determination, light irradiation power of a light irradiation element so as to satisfy the standard, determines a read offset amount based on a result of the adjustment, and performs control so that a position of a read head is shifted based on the determined read offset amount.

Abstract: The present invention provides a method for manufacturing a thin film transistor including processing of irradiating an amorphous silicon film 8 deposited on a substrate with laser light. The method comprises: a laser annealing step for forming a polysilicon film 9 including a channel region 52 by irradiating an area including a formation region of the region 52 in the film 8 with the laser light such that the area including the formation region is heated, melted, and recrystallized; and a removing step for etching off an area outside the region 52 from the polysilicon film 9. Thus, the present invention can provide a method for manufacturing a thin film transistor and a mask for use in the manufacturing method that are capable of promoting the recrystallization of the film 8 and thereby improving its electron mobility even when laser irradiation has to be performed under restricted irradiation conditions.

Abstract: A thermally assisted magnetic recording head and a thermally assisted magnetic recording disk drive are disclosed. The thermally assisted magnetic recording head includes a slider body, a laser substrate, a laser and a magnetic head, wherein the laser substrate is provided on the slider body, the laser is provided on the laser substrate, and the magnetic head is provided at a front end of the slider body. The magnetic head includes an optical waveguide facing the laser. The angle between a light incident surface of the optical waveguide and an incident direction of a laser light incident on the optical waveguide is less than 90 degrees. The thermally assisted magnetic recording disk drive includes a plurality of magnetic disks and a magnetic head suspending frame. A front end of the magnetic head suspending frame is provided with the thermally assisted magnetic recording heads mentioned above.

Abstract: A magnetoresistive memory device includes a magnetic-exchange-coupled layer stack containing a free layer, a reference layer and an electrically conductive, non-magnetic interlayer exchange coupling layer located between the free layer and the reference layer, and an insulating spacer layer located in a series connection with the magnetic-exchange-coupled layer stack between a first electrode and a second electrode. The first electrode and the second electrode are configured to provide a programming voltage across the magnetic-exchange-coupled layer stack and the insulating spacer layer.

Abstract: An apparatus comprises a slider configured to facilitate heat assisted magnetic recording and a submount affixed to the slider. A laser unit is affixed to the submount and comprises a laser operable in a non-lasing state and a lasing state. A heater is embedded in the laser unit or the submount. The heater is configured to generate preheat for heating the laser during the non-lasing state and to generate steering heat for heating the laser during the lasing state.

Abstract: Embodiments of synthetic garnet materials having advantageous properties, especially for below resonance frequency applications, are disclosed herein. In particular, embodiments of the synthetic garnet materials can have high Curie temperatures and dielectric constants while maintaining low magnetization. These materials can be incorporated into isolators and circulators, such as for use in telecommunication base stations.

Abstract: Embodiments of the present disclosure generally relate to data storage devices, and more specifically, to storage devices employing an energy-assisted magnetic recording write head. The write head may comprise a main pole, a trailing shield, a conducting gap disposed between the main pole and the trailing shield, and one or more current blockers. The conducting gap may be conformal with the main pole. The one or more current blockers may be configured to direct the current from the main pole to the trailing shield through the conducting gap. The one or more current blockers may be further configured to recess the conducting gap away from the media facing surface. The one or more current blockers may be configured to direct the current away from a media facing surface of the write head.

Abstract: A microwave assisted magnetic recording writer has a main pole (MP) with a write gap formed between the MP trailing side and a trailing shield, a side gap between each MP side and a side shield, and a leading gap between the MP leading side and a leading shield. A spin torque oscillator (STO) is formed in at least each side gap and recessed from the air bearing surface to reduce wear. Each STO has a flux guiding layer (FGL) with a magnetization that flips to a direction substantially opposite to the gap field when a current of sufficient density is applied from the adjacent shield towards the MP thereby forcing additional flux out of the MP at the ABS to enhance writability on a magnetic recording medium. Accordingly, the gap between the recessed STO and ABS is reduced to provide enhanced area density capability without sacrificing overwrite.

Abstract: A transformer includes a magnetic core, a first coil unit and a second coil unit. The first coil unit is disposed within the magnetic core and includes a laminated board having layers laminated therein and conductive patterns. Respective ones of the conductive patterns are disposed on the laminated layers. The second coil unit includes a conductive wire spaced apart from the conductive patterns of the laminated board by an insulating distance. The conductive wire includes a triple-insulated wire surrounded by three sheets of insulating paper to maintain the insulating distance from the conductive patterns.

Abstract: A heat-assisted magnetic recording (HAMR) medium has a heat-sink layer, a chemically-ordered FePt (or CoPt) alloy magnetic layer and a MgNiO intermediate layer between the heat-sink layer and the magnetic layer. The intermediate layer is a solid substitution crystalline alloy of the form (Mg(100-y)Niy)O, where y is less than 10 and greater than or equal to 0.5. The magnetic layer may be formed directly on the MgNiO intermediate layer, in which case the MgNiO intermediate layer functions as both a seed layer and a thermal barrier layer. The HAMR medium may also include an optional layer of crystalline “pure” MgO directly below or directly above the MgNiO intermediate layer. If the MgO layer is located directly above the MgNiO intermediate layer then the MgNiO intermediate layer functions primarily as a thermal barrier layer. The HAMR medium with the MgNiO intermediate layer provides a substantial improvement in corrosion resistance.

Abstract: An apparatus includes a first magnetic layer. A second magnetic layer overlies the first magnetic layer and is magnetically softer than the first magnetic layer. An exchange control layer is between the first magnetic layer and the second magnetic layer. The includes a higher Ms (saturation magnetization) than the first magnetic layer at room temperature.

Abstract: A transformer includes a magnetic core, a first coil unit and a second coil unit. The first coil unit is disposed within the magnetic core and includes a laminated board having layers laminated therein and conductive patterns. Respective ones of the conductive patterns are disposed on the laminated layers. The second coil unit includes a conductive wire spaced apart from the conductive patterns of the laminated board by an insulating distance. The conductive wire includes a triple-insulated wire surrounded by three sheets of insulating paper to maintain the insulating distance from the conductive patterns.

Abstract: Systems and methods for coating a near field transducer in a dielectric material are described. In one embodiment, the method may include forming a liquid solution comprising at least a first dielectric and a disk surface lubricant, forming a coating of the liquid solution on an outer surface of a storage medium based at least in part on dipping the storage medium in the liquid solution, and accumulating a first set of molecules of the first dielectric on a near field transducer (NFT) of a HAMR head based at least in part on evaporating a first portion of the first dielectric in the coating by performing a first HAMR writing operation that shines a laser on the coating.

Abstract: A manufacturing method for a waveguide includes forming a core including a first and a second layer. The first layer has a top surface including a first region opposed to a bottom surface of the second layer, and a second region not opposed to the bottom surface of the second layer. Forming the core includes a step of forming an initial first layer, an etching stopper layer on the second region of the top surface of the initial first layer, an initial second layer on the initial first layer and the etching stopper layer, and a step of etching the initial second layer until the etching stopper layer is exposed, to make the initial second layer into the second layer. A difference between the refractive index of the etching stopper layer and the core is smaller than or equal to 10% of the refractive index of the core.

Abstract: A magnet structure for a magnetic data storage medium erasing apparatus includes a first half comprising a first plurality of magnets arranged symmetrically, having polarization direction of adjacent magnets in quadrature and at an oblique angle with respect to a plane of symmetry. A second half comprises a second plurality of magnets arranged symmetrically, having polarization direction of adjacent magnets in quadrature and at an oblique angle with respect to the plane of symmetry. The second half is arranged symmetrically with respect to the first half, wherein the first half and the second half are separated by an air gap disposed about the plane of symmetry.

Abstract: Bottom tracks are written to a recording medium using a first setting of a spin-torque oscillator of a single microwave assisted magnetic recording (MAMR) head. Top tracks are written interlaced between and partially overlapping the bottom tracks using the single MAMR head at a second setting of the MAMR head, the first and second settings resulting in different bit aspect ratios for the top and bottom tracks.

Abstract: An apparatus includes a first waveguide core extending along a light-propagation direction and configured to receive light from a light source at a combined transverse electric (TE) mode and a transverse magnetic (TM) mode. A second waveguide core is spaced apart from the first waveguide core and is configured to couple light at a TM mode to the second waveguide core. A near-field transducer (NFT) is disposed at a media-facing surface of a write head, the NFT receiving the light from the first waveguide core or the second waveguide core and heating a magnetic recording medium in response thereto.

Abstract: A spin torque transfer (STO) assisted magnetic recording structure is disclosed wherein a STO device has capability to generate a radio frequency (RF) field on a magnetic bit to lower the required write field during a write process. The STO device contains a field generation layer (FGL) with a magnetization that flips to a direction opposite to the write gap field when a current of sufficient current density is applied thereby increasing reluctance in the write gap and causing a larger write field output at the air bearing surface. A key feature is that a single spin polarization (SP) layer and an antiferromagnetically coupled SP layer comprised of SP1 and SP2 layers are formed on opposite sides of the FGL. SP1 magnetization is greater than SP2 magnetization. Additive torque from SP and SP2 layers on the FGL enables FGL flipping while SP1 and SP2 precessional states provide the RF field.

Abstract: An input waveguide is disposed on a substrate-parallel plane and configured to receive light from an input surface. A mode converter joins the input waveguide at a junction away from the input surface. The mode converter converts the light from a fundamental mode to a higher-order mode. An input coupler is proximate to and overlapping the input waveguide parallel to the substrate-parallel plane. The input coupler extending from the input surface to the mode converter and has an asymmetric taper that transitions from a wider crosstrack dimension near the input surface to a narrower crosstrack dimension away from the input surface.

Abstract: A slider comprises an air bearing surface (ABS) and is configured to interact with a magnetic recording medium. A writer is provided on the slider and comprises a write coil having a media-facing surface situated at the ABS. Cooling arms project laterally from peripheral surfaces of the write coil and extend along the ABS. The media-facing surface of the write coil and the cooling arms are exposed to the ABS to facilitate increased cooling of the write coil at the ABS.

Abstract: An apparatus comprises a slider configured for magnetic recording. The slider comprises an air bearing surface (ABS), a writer, a reader, and a plurality of electrical bond pads. A thermocouple is situated at the ABS proximate the reader and coupled to a pair of the electrical bond pads. The thermocouple is dimensioned to sense for a thermal asperity on a surface of a magnetic recording medium.

Abstract: A transformer includes a magnetic core, a first coil unit and a second coil unit. The first coil unit is disposed within the magnetic core and includes a laminated board having layers laminated therein and conductive patterns. Respective ones of the conductive patterns are disposed on the laminated layers. The second coil unit includes a conductive wire spaced apart from the conductive patterns of the laminated board by an insulating distance. The conductive wire includes a triple-insulated wire surrounded by three sheets of insulating paper to maintain the insulating distance from the conductive patterns.

Abstract: Devices having an air bearing surface (ABS), the devices include a write pole; a near field transducer (NFT) including a peg and a disc, wherein the peg is at the ABS of the device; an overcoat, the overcoat including a low surface energy layer.

Abstract: An apparatus comprises a first electrical contact, a second electrical contact, and a semiconductor device disposed between the first and second electrical contacts. The semiconductor device comprises a laser diode and a temperature control unit. The laser diode comprises p-type semiconductor material and n-type semiconductor material. The temperature control unit comprises p-type semiconductor material, n-type semiconductor material, and a resistor coupled to the laser diode. One of the p-type semiconductor material and the n-type semiconductor material is shared by the laser diode and the temperature control unit.

Abstract: Disclosed herein are write heads for data storage devices, methods for making and using such write heads, and data storage devices comprising such write heads. A write head comprises a near-field transducer (NFT), a thermal sensor, and a shield disposed between the NFT and the thermal sensor, wherein the shield comprises a magnetic or conductive material, such as, for example, Cu, Ag, Au, Al, Rh, Ti, Cr, Mo, Fe, Co, or Ni or an alloy that includes Cu, Ag, Au, Al, Rh, Ti, Cr, Mo, Fe, Co, and/or Ni. In some embodiments, the thermal sensor comprises a first lead and a second lead, and the shield is connected to the first lead but not the second lead to provide heat sinking for the shield.

Abstract: A heat-assisted magnetic recording (HAMR) medium has a rhodium (Rh) or Rh-based alloy heat-sink layer. The Rh or Rh-based alloy does not roughen when annealed and thus does not require an intermediate layer between it and the MgO seed layer for the recording layer, so the MgO seed layer can be formed directly on and in contact with the Rh or Rh-based alloy heat-sink layer. The Rh or Rh-based alloy heat-sink layer is formed on a seed layer or multilayer that allows the Rh or Rh-based alloy to grow with the desired face-centered-cubic (fcc) crystalline structure.

Abstract: A recording head has a waveguide core with an input facet at an input surface. The waveguide core extends to a near-field transducer at a media-facing surface of the recording head. First and second cladding regions are co-planar with and on either cross-track side of the waveguide core. First and second pseudo-slab regions are co-planar with and on outer cross-track sides of the respective first and second cladding regions. The first and second pseudo-slab regions have an index of refraction higher than that of the first and second cladding regions. The first and second pseudo-slab regions confine and channel stray light away from the near-field transducer.

Abstract: An imaging lens assembly includes a plurality of lens elements, wherein at least one of the lens elements is a dual molded lens element. The dual molded lens element includes a light transmitting portion and a light absorbing portion. The light transmitting portion includes an effective optical section. The light absorbing portion is located on at least one surface of an object-side surface and an image-side surface of the dual molded lens element, wherein a plastic material and a color of the light absorbing portion are different from a plastic material and a color of the light transmitting portion, and the light absorbing portion includes an opening. The opening is non-circular and disposed correspondingly to the effective optical section.

Abstract: Devices having air bearing surfaces (ABS), the devices including a near field transducer (NFT) that includes a disc configured to convert photons incident thereon into plasmons; and a peg configured to couple plasmons coupled from the disc into an adjacent magnetic storage medium, wherein at least one of a portion of the peg, a portion of the disc, or a portion of both the peg and the disc include a multilayer structure including at least two layers including at least one layer of a first material and at least one layer of a second material, wherein the first material and the second material are not the same and wherein the first and the second materials independently include aluminum (Al), antimony (Sb), bismuth (Bi), boron (B), barium (Ba), calcium (Ca), cerium (Ce), chromium (Cr), cobalt (Co), copper (Cu), erbium (Er), gadolinium (Gd), gallium (Ga), germanium (Ge), gold (Au), hafnium (Hf), indium (In), iridium (Ir), iron (Fe), lanthanum (La), magnesium (Mg), manganese (Mn), molybdenum (Mo), nickel (Ni), ni

Abstract: An apparatus comprises a slider having a media-facing surface and that is configured for heat-assisted magnetic recording. The slider comprises a write pole, a heatsink layer, and a diffusing metal. The write pole includes two or more sides extending into the slider and a pole tip at the media-facing surface. The heatsink layer is proximate at least part of the two or more sides of the write pole, and a first portion of the heatsink layer is proximate the pole tip. The diffusing metal is disposed proximate the write pole.

Abstract: A recording head has a waveguide core layer that delivers light from a light source to a region proximate a magnetic write pole. A near-field transducer is formed of a thin film of Rh or Ir deposited over the waveguide core layer. The near-field transducer includes an enlarged part with two straight edges facing a media-facing surface and at obtuse angles relative to the media-facing surface. A peg extends from the enlarged part towards the media-facing surface. The waveguide core layer has a terminating end with terminating edges that align with the two straight edges of the near-field transducer.

Abstract: A magnetic recording medium is provided that includes, in the order recited, a substrate; a first seed layer; a second seed layer containing ZnO; a third seed layer containing MgO; and a magnetic recording layer containing an ordered alloy. The first seed layer contains Ru and at least one material selected from the group consisting of oxides, carbides, and nitrides. Employing seed layers enables the magnetic recording medium to be a perpendicular magnetic recording medium by having the magnetic recording layer contain an ordered alloy suitable for perpendicular magnetic recording. Recording density is improved thereby while ensuring required thermal stability. Further, the invention achieves an increased thickness of the magnetic layer and a reduced grain size.

Abstract: A transformer includes a magnetic core, a first coil unit and a second coil unit. The first coil unit is disposed within the magnetic core and includes a laminated board having layers laminated therein and conductive patterns. Respective ones of the conductive patterns are disposed on the laminated layers. The second coil unit includes a conductive wire spaced apart from the conductive patterns of the laminated board by an insulating distance. The conductive wire includes a triple-insulated wire surrounded by three sheets of insulating paper to maintain the insulating distance from the conductive patterns.

Abstract: An apparatus includes a slider configured for heat-assisted magnetic recording. An input coupler of the slider is configured to-receive light produced by a light source. A waveguide of the slider comprises a waveguide core tapering from a first portion having a first cross sectional width to a second portion having a second cross sectional width along the light propagation direction. The second cross sectional width being smaller than the first cross sectional width, and the second portion having an output end. The waveguide includes at least one cladding layer comprising a metallic material. The at least one cladding layer surrounds at least the core. The at least one cladding layer is configured to sink heat away from the waveguide core. The waveguide is configured to provide a surface plasmon-enhanced near-field radiation pattern proximate the output end in response to the light received at the transducer region.

Abstract: According to one embodiment, a magnetic recording and reproducing device includes a magnetic recording medium, a magnetic head, and a controller. The controller implements a first operation and a second operation. The first operation is implemented in a first information recording interval including a first recording interval and a first non-recording interval. The second operation is implemented in a second information recording interval including a second recording interval and a second non-recording interval. The first operation includes in the first recording interval, generating a first signal magnetic field from the magnetic head, and in the first non-recording interval, generating a first non-signal magnetic field from the magnetic head. The second operation includes in the second recording interval, generating a second signal magnetic field from the magnetic head, and in the second non-recording interval, generating a second non-signal magnetic field from the magnetic head.

Abstract: A magnetic pulse recording method is disclosed wherein a magnetic field is turned off for a portion (tOFF) of a bit duration before or after total recording time is completed for each bit. Typical bit lengths of 10 nm to 50 nm must be less than the main pole down-track length, and total recording time (tREC) must be less than the bit duration such that bit duration equals (tREC+tOFF). In a random bit sequence, tREC may be maintained for each bit while tOFF increases as bit duration increases. The method applies to mobile hard disk drives (HDD) with 2.5 inch disks, and to nearline HDD with 3.5 inch disks where bit durations vary from 0.3 to 1.2 ns for recording velocities between 10 and 47 m/sec. The time required to turn off the field may be <10 picoseconds, and comprise a linear or non-linear waveform.

Abstract: A combination of a semiconductor member and a metal member is selected appropriately from a view point of increasing an enhancement factor of a near-field light. A device (1) has a semiconductor member (101) and a metal member (102), a near-field light is generated at the metal member when an energy is supplied to the semiconductor member, the metal member is made of an alloy including a first metal and a second metal, a condition of Rm1<Rs<Rm2 is satisfied, wherein a resonance wavelength of the first metal is Rm1, a resonance wavelength of the second metal is Rm2, and a resonance wavelength of the semiconductor member is Rs.

Abstract: Devices having air bearing surfaces (ABS), the devices include a near field transducer (NFT) that includes a disc configured to convert photons incident thereon into plasmons; and a peg configured to couple plasmons coupled from the disc into an adjacent magnetic storage medium, wherein the disc includes a disc material and the peg includes a peg material, wherein the disc material is different from the peg material and wherein the disc material has a first real part of the permittivity and a peg material has a second real part of the permittivity and the second real part of the permittivity is not greater than the first real part of the permittivity.

Abstract: According to one embodiment, a magnetic disk drive records and reproduces referential data and measures a referential characteristic value in a state in which supply of a STO voltage is stopped, executes control of reducing a temperature set value of a heater at a recording operation, based on the referential characteristic value, records and reproduces corrected data and measuring a corrected characteristic value in a state of supplying the STO voltage with a polarity opposite to a polarity at a general operation, while varying the temperature set value at a recording operation, compares the referential characteristic value with the corrected characteristic value and obtaining a difference, and corrects the temperature set value based on the difference.

Abstract: A slider of a heat-assisted recording head comprises electrical bond pads coupled to bias sources and a ground pad, an air bearing surface, and a waveguide configured to receive light from a laser source. A contact sensor proximate the air bearing surface is coupled between a first bond pad and a second bond pad. A bolometer is coupled to a reference thermal sensor. The bolometer is situated at a slider location that receives at least some of the light communicated along the waveguide. The reference thermal sensor is situated at a slider location unexposed to the light communicated along the waveguide. The bolometer and reference thermal sensor are coupled between the first and second bond pads and in parallel with the contact sensor. A ground connection is coupled to the ground pad and at a connection between the bolometer and the reference thermal sensor.

Abstract: Before writing to a heat-assisted magnetic recording medium, a DC signal modulated with an AC signal is applied to a laser of a read/write head. A modulation level of an optical power sensor is measured, the optical power sensor being coupled to detect optical output of the laser in response to the modulated current. A target value of the DC signal that causes the modulation levels to reach a predetermined value between zero and a maximum value is determined and used to set a bias current for subsequent activation of the laser based.