HAMR recording / reproducing head

Abstract

To provide a magnetic recording head, a design method thereof, and a magnetic recording device that provide thermally activated protection against media damage during dynamic events such as operational shocks, load / unload processes, and emergency power-off.SOLUTION: A perpendicular magnetic recording (PMR) read / write transducer head for heat-assisted magnetic recording (HAMR) includes active nano bumper pads formed from thermally activated dynamic flying height (DFH) bulges that protrude closely on either side of the read / write element, and these bumper pads, which can be multiple, are arranged around the perimeter of he transducer head to absorb the heat generated by active heating element, including the write current. When this energy is absorbed, the bulges expand and change shape, protruding closely outward from the slider air bearing surface (ABS), protecting the read / write head from intentional and unintentional touchdowns.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to magnetic recording heads that write to magnetic recording media, and in particular to magnetic recording head designs that provide thermally activated protection against media damage during dynamic events such as operational shocks, load / unload processes, and emergency power-offs. [Background technology]

[0002] Hard disk drives (HDDs) are increasing the recording density of magnetic disks on which data is stored. This trend is driving demands for improved performance from the thin-film magnetic heads that record and read that data. The most commonly used thin-film read / write heads are hybrid types that combine a magnetic field detection element, such as a giant magnetoresistive (GMR) read sensor, with a magnetic recording element, such as an electromagnetic coil induction element. These two types of devices are stacked on top of each other and mounted on a rectangular parallelepiped device called a slider. The slider is aerodynamically lifted at a height called the fly height (FH) and literally flies over the rotating surface of the disk. The read / write head is mounted on the slider and operates to read and write data signals from and to the magnetic disk, the typical magnetic recording medium of HDDs. The magnetic recording portion of the read / write head is a tiny electrically activated coil that induces a magnetic field in the magnetic pole. This magnetic field is generated in a narrow write gap (WG) and can change the magnetic moment of small magnetic particles or groups of particles embedded in the surface of the magnetic disk. If the magnetic moments of the embedded magnetic particles are perpendicular to the surface of the magnetic disk and in a manner that can be switched between up and down relative to the surface of the magnetic disk, it will be called perpendicular magnetic recording (PMR). The perpendicular configuration creates a more densely packed area for magnetic recording.

[0003] Perpendicular magnetic recording (PMR) heads, which record perpendicular to the surface of the magnetic recording medium, have increased the recording density of hard disk drives (HDDs) to 100 Gb / in2 However, even with a PMR head, the thermal stability and superparamagnetic limit of the medium make it impossible to achieve a data rate of 1 Tb / in 2 Recording densities beyond this are difficult to achieve. To achieve even higher recording densities, a new technology called thermally assisted magnetic recording (HAMR) has been developed. Simply put, magnetic recording media that can be effectively used for such ultra-high-density recording must have an extremely high coercivity so that recorded data remain stable even when subjected to heat. However, the high coercivity required to maintain recorded data makes it difficult to actually create magnetic transitions and record data on the magnetic recording medium with the limited magnetic flux density of a small PMR head. One way to achieve this is to heat the magnetic recording medium during the recording process, temporarily reducing the magnetic coercivity of the magnetic recording medium, and then record data on the heated surface. When the surface cools, the magnetic coercivity of the magnetic recording medium returns to its value at ambient temperature, and the data recorded on the magnetic recording medium becomes stable.

[0004] As is well known, a typical HAMR is a read / write head (here, a slider-mounted PMR head) that includes (1) a laser diode that provides photothermal energy via optical radiation, (2) an optical waveguide that transmits the optical radiation near the recording surface, and (3) a plasmon generator positioned near the recording surface. The plasmon generator is a device that receives the optical radiation, converts it into plasmon mode excitations via electromagnetic coupling, and transfers the energy from the plasmon near-field to a region of the recording medium. Because the near-field is not radiation, it is not subject to diffraction and is highly localized. The localized near-field energy appears as a near-field spot at the tip of the air-bearing surface (ABS) of the plasmon generator. This small near-field spot appears at the ABS of the PMR read / write head, adjacent to the tip of the magnetic pole from which the PMR write portion emerges.

[0005] The near-field spot generated during a write operation causes a very localized temperature rise in the magnetic recording medium. This reduces the coercivity of the magnetic recording medium, facilitating magnetic recording. At the same time, the near-field energy can produce very sharp or localized heat-induced protrusions, which creates many problems that must be addressed. Because this disclosure is directed to a read / write head, these HAMR components that generate the near-field spot are already well known in the art and will not be described in detail. Also, the features of the HAMR head where the near-field energy is stored and where the read / write operation occurs will not be described. As a result, HAMR drives use glass substrate media to address this issue.

[0006] In thermally assisted magnetic recording (HAMR), a near-field transducer induces a local temperature rise in the magnetic recording medium, reducing the medium's coercivity and thereby assisting magnetic writing. Therefore, HAMR drives use glass substrate media rather than aluminum substrates to prevent aluminum from deforming due to high temperatures. The glass used in HAMR is harder and rougher than aluminum media, which increases head wear during TD calibration within the drive. Furthermore, head-disk interference (HDI) continues to increase due to read / write clearance. HDI in HAMR drives significantly reduces reader reliability.

[0007] Furthermore, HAMR generates an additional heat source during writing, resulting in a higher passive flying height (PFM) than PMR. The laser-induced writer protrusion (LIWP) depends on the Iop (laser diode operating current) and the head writer design. This additional protrusion requires an additional passive flying height (PFH) to match the HAMR head-to-media spacing (HMS). Increasing the passive flying height (PFH) increases the drive of the read heater, resulting in an increase in the reader temperature. This leads to thermal noise, which degrades the reader's performance. To solve this problem, a new DFH bulge was developed to protect the read element (reader) from HDI and reduce the reader's temperature during operation. Summary of the Invention

[0008] A primary objective of this disclosure is to provide TD protection to various portions of a HAMR write head by adding "active" bumper pads whose shape is thermally altered by the effects of heat already generated within the write head.

[0009] A second objective of this disclosure is to provide a bumper pad that protrudes due to the effects of heat already generated by elements within the HAMR head, which increases the TD contact area and improves reliability by controlling the location of the minimum point (closest to the disk) away from the sensor location.

[0010] A third objective of the present disclosure is to provide bumper pads whose global and local protrusion effect shifts TD contact to shields and other areas designed to absorb the contact, thereby avoiding contact with more sensitive areas of the write head.

[0011] A fourth object of the present disclosure is to provide a bumper pad with a controllable shape to create thermal protrusion asymmetry that may be beneficial to the performance of a HAMR write head.

[0012] The objectives of the present disclosure are achieved by the design of a HAMR read / write head configured for perpendicular magnetic recording (PMR). The head includes a magnetically shielded GMR read head and a separate magnetically shielded inductive write head driven by a write current. These elements protrude from the ABS (magnetic surface) of the PMR. The PMR also includes independently operating heater elements Hr and Hw. These heater elements are positioned adjacent to the read and write heads, respectively, but are closely spaced from the ABS. The PMR also includes at least one head-disk interference sensor (HDI), which is mounted on the read / write head. To utilize the HAMR system, the recording head forms a narrow write region at the ABS, where magnetic flux emanates from a protruding pole tip and near-field plasmon energy is emitted from the trailing edge of the pole tip, enabling writing to the magnetic recording medium. Finally, a pair of thermally activated bumper pads, whose shape changes due to localized thermally induced protrusions, are positioned on either side of the narrow write region of the write element to protect the write region by shifting the potential point of disk contact away from the write head and toward the magnetic shield in the event of touchdown (TD) or other forms of head-disk interference (HDI). [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of a conventional HAMR head, showing the read heater below the read shield. [Figure 2A] FIG. 2A is a bottom view of the conventional lead heater shown in FIG. [Figure 2B] FIG. 2B is a preferred embodiment of the disclosed central recessed DFH heater design. [Figure 3A] FIG. 3A is a down-track profile of the DFH ridge on the conventional leader heater of FIG. 2A. [Figure 3B]FIG. 3B is a cross-track profile of the DFH protuberance on the conventional leader heater of FIG. 2A. [Figure 3C] FIG. 3C is a downtrack profile of the DFH bulge above the disclosed center-recess DFH heater of FIG. 2B. [Figure 3D] FIG. 3D is a cross-track profile of the slider center read heater bulge above the DFH heater disclosed in FIG. 2B. [Figure 4A] FIG. 4A is a flight profile of the slider bump in the down-track direction for the conventional reader heater of FIG. 2A. [Figure 4B] FIG. 4B is a flight profile of the slider bump in the cross-track direction for the conventional reader heater of FIG. 2A. [Figure 4C] FIG. 4C is a slider bump flight profile in the down-track direction for the DFH heater design disclosed in FIG. 2B. [Figure 4D] FIG. 4D is a flight profile of the slider bump in the cross-track direction for the DFH heater design disclosed in FIG. 2B. [Figure 5A] FIG. 5A shows the read heater induction temperature profile for each of the conventional and disclosed read heaters during simulated operation. [Figure 5B] FIG. 5B shows the read heater induction temperature profile for each of the conventional and disclosed read heaters during simulated operation. [Figure 6] FIG. 6 shows a head gimbal assembly (HGA) to which the PMR of the present disclosure is flexibly mounted. [Figure 7] FIG. 7 shows a side view of the pair of HGAs shown in FIG. [Figure 8] FIG. 8 is a top view of the HGA shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] In dual independent heater (DIH) operation, the reader heater is typically located below the reader shield structure S1, and the read element (GMR element) is located between the read shield structure S1 and the read shield S2A.

[0015] 1 shows the structure of a reproducing heater 15 and a reproducing shield (A1) 10. A part of a magnetic recording device 100 is also shown, but further explanation is omitted. Layer 15 is a reproducing heater, and details are shown in FIGS. 2A and 2B.

[0016] FIG. 2A shows a conventional read heater structure 15, where the conventional heater element is a conductive serpentine structure formed under a heat shield 10.

[0017] In conventional read heater operation, the read heater 15 is energized by passing an electric current through it, transferring heat to the read shield (S1) 10. The bulging of the read heater 15 occurs due to thermal expansion of the read shield structure 20. Figure 2A shows a conventional read heater bulging due to thermal expansion. Figure 2B shows the central recessed read heater 20 disclosed in the present invention and its regions (30 and 40). These regions cause the read shield 10 to bulge unconventionally due to thermal expansion of the differently shaped regions 30, 40.

[0018] During touchdown (TD) of the lead heater, the lead heater protrusion formed by the present invention provides sufficient TD area to change the reader spacing and induce TD oscillation of the lead heater TD. Figure 3A shows the conventional lead heater protrusion in the down-track direction, and Figure 3B shows the conventional lead heater protrusion in the cross-track direction. It can be seen that the maximum protrusion point of the conventional heater is at the center of the slider, very close to the reader. Figure 3C is a profile of the DFH protrusion in the down-track direction above the disclosed central recessed DFH heater of Figure 2B. Figure 3D is a profile of the lead heater protrusion in the center of the slider in the cross-track direction above the disclosed DFH heater of Figure 2B. As shown in Figure 3D, the protrusion disclosed by the present invention has a separated double peak created by the enlarged regions (30, 40, 30) that function like two nanobumpers, dividing the maximum protrusion point at a cross-track location approximately ±6 micrometers from the center. The reader location is at the center (not the protruding peak) and the double peaks acting as nanobumpers protect the reader element from HDI / TD abrasion.

[0019] Figures 4A-4D show read TD and FH (flying height) profiles. Figure 4A is a slider bump fly profile in the down-track direction for the conventional read heater shown in Figure 2A. Figure 4B is a slider bump fly profile in the cross-track direction for the conventional read heater shown in Figure 2A. Figure 4C is a slider bump profile in the down-track direction for the DFH heater design disclosed in Figure 2B. Figure 4D is a slider bump fly profile in the cross-track direction for the disclosed DFH heater design shown in Figure 2B. The read spacing in the TD for the conventional read heater is less than 0.1 nm (1 Å) at the RTD. The disclosed design includes a "nano-bumper" to protect the reader at the RTD. The disclosed central recessed read heater results in a read spacing of 0.3 nm at the RTD. Depending on the HDD HDI / TD wear, the read spacing can be adjusted from 0 nm to 1 nm by fine-tuning the central recess of the read heater design.

[0020] Furthermore, the disclosed DFH bump has a wider bump width than the conventional bump. Therefore, the TD area is enlarged, and sufficient TD vibration can be generated in the drive. Figure 5A shows the conventional read TD area (55 square micrometers). As shown in Figure 5B, the bump of the present invention enlarges the read TD area to 88 square micrometers. The width of the bump and the maximum protrusion position can be adjusted by fine-tuning the central recessed heater.

[0021] The disclosed DFH bulge is produced by a central recessed heater, which results in a longer distance between the heater and the leader compared to conventional heaters.

[0022] The read heater induced temperature profile in FIG. 5A shows that the highest temperature of the read heater is located in the center of the S1 read shield. The reader temperature shown is 59°C within the RTD. In contrast, the read heater induced temperature profile in FIG. 5B shows the disclosed double-peak ridge, with the read heater temperature peak point split between the sides of the S1 read shield. As shown, the reader temperature is 55°C within the RTD. Therefore, the disclosed inventive ridge reduces the read heater temperature rise by 12% (4°C). This reader temperature reduction contributes to improved reader performance and reliability.

[0023] The member by which the HGA 1200 is attached to the arm 1260 is called the head arm assembly 1220. The arm 1260 moves the read / write head 1100 in the cross-track direction (arrow) over the medium 1140 (here, a hard disk). One end of the arm 1260 is attached to the base plate 1240. A coil 1231, which is part of a voice coil motor (not shown), is attached to the other end of the arm 1260. A bearing 1233 is provided in the middle of the arm 1260. The arm 1260 is rotatably supported by a shaft 1234 attached to the bearing 1233. The arm 1260 and the voice coil motor that drives the arm 1260 form an actuator.

[0024] 7 and 8, a magnetic recording device incorporating a head stack assembly 1250 and a slider-mounted HAMR writer 1100 is shown. The head stack assembly is an element where the HGA 1200 is attached to the arm of a carriage that has multiple arms for engaging multiple disks 1140. The multiple disks are mounted on a spindle 1261. FIG. 7 is a side view of this assembly, and FIG. 8 is a plan view of the entire magnetic recording device.

[0025] Finally, referring to FIG. 8, the head stack assembly 1250 is shown incorporated into a magnetic recording device 1290. The magnetic recording device 1290 has multiple magnetic recording media 1114 mounted on a spindle motor 1261. Each magnetic recording medium 1114 is provided with two HAMR elements 1100 arranged opposite each other with the magnetic recording medium 1114 sandwiched between them. The head stack assembly 1250 and actuator (excluding the write head itself) function as a positioning device to support the PMR head 1100 and, in response to electronic signals, position the PMR head correctly facing the medium surface. The read / write head uses its internal magnetic poles to record information on the surface of the magnetic recording medium.

[0026] Based on the modeling results shown in the figures, it can be seen that the design of the present invention has many advantages. 1) The design of the present invention allows for contact area control to prevent TD "over-push" (over-compensation of heater power due to TD detection failure) by adjusting the bumper dimensions and protrusion amount. 2) The design of the present invention minimizes point shift from the sensor to the bumper pad to ensure head reliability. 3) The local protrusion height and shape of the bumper can be adjusted by selecting the bumper dimensions according to differences in wafer design, head process, and writing conditions. 4) The design of the present invention has double peaks that act as "nano-bumpers" to protect the reader from HDI / TD wear by shifting the DFH TD point from the center to the nano-bumper (S1 read shield side). 5) In our design, the leader spacing @TD is 0.3 nm, which can be adjusted from 0 nm to 1 nm by fine-tuning the heater design according to the HDI / TD wear conditions of the HDD. 6) The DFH protuberance of the present invention can increase the TD area from 55 to 88 square micrometers for sufficient TD vibration. 7) The DFH bulge disclosed in this invention reduces the temperature rise of the leader by 12% (4°C) compared to the conventional bulge, improving the performance and reliability of the leader.

[0027] As will be appreciated by those skilled in the art, the present disclosure is illustrative rather than limiting. Modifications and variations are possible in the methods, materials, structures, and dimensions used to form and provide a HDD slider-mounted PMR recording head configured for HAMR. The slider has an ABS topography that includes an active nano-bumper pad activated by a temperature-induced bulge surrounding a narrow reader / writer region configured to operate in conjunction with a plasmonic near-field spot, the bumper undergoing a shape change due to thermal protrusion effects occurring within the PMR. This shape change protects portions of the PMR head during intentional and unintentional TD events while providing a shape change. Such a device and its method of operation can be formed and provided in accordance with the spirit and scope of the present disclosure, as defined by the appended claims.

Claims

1. A thermally assisted magnetic recording (HAMR) read / write head with a thermally activated DFH (Dynamic Flying Height) bulge to protect the read element from various forms of HDI (Head-Disk Interference) and reduce reader temperature and wear during operation, comprising: a perpendicular magnetic recording (PMR) read / write head configured for HAMR, having a magnetically shielded GMR read head exposed at the ABS and a separate magnetically shielded inductive write head actuated by a write current; a heater element Hr and a heater element Hw adjacent to the read head and the write head, respectively, spaced apart from the ABS and operating independently; a read heater mounted to the heat shield and having at least one centrally located recess that forms a protuberance in the read shield when thermally activated by the passage of an electric current; Equipped with the protuberance has a physical shape including multiple double peaks corresponding to multiple symmetrically separated recesses created by thermal expansion of the reader shield structure; The double peaks act as nano-bumpers to protect the reader element from HDI / TD abrasion; The central recessed heater increases the distance between the heater and the leader compared to a conventional leader that does not have this geometry requirement; whereby the write head forms a small protected write area at the ABS, magnetic flux is emitted by a pole tip exposed at the ABS, and near-field plasmon energy emerges at the trailing edge of the pole tip to enable writing to the disk medium; the pair of thermally activated bumper pads are reshaped by localized heat-induced protrusions and are positioned on either side of the narrow write area of ​​the write element to protect the area by moving potential points of contact with the disk toward the shield in the event of touchdown (TD) or other forms of head-disk interference (HDI). Heat-assisted magnetic recording (HAMR) read / write head.

2. the thermally active bumper pad formed from the protrusion extends proximally from the ABS and is configured to absorb thermal energy generated by the heater, the write current, and the HAMR device, thereby providing the bumper pad with increased thermal protrusion surface area and enhanced protection for the write head; The heat-assisted magnetic recording (HAMR) read / write head of claim 1 .

3. both of the pair of thermally activated bumper pads have the same shape, are separated, and are symmetrically positioned, whereby each of the pair of thermally activated bumper pads, when thermally activated, produces a protrusion similar to that of the other thermally activated bumper pad, symmetrically changing the response of the slider in the cross-track direction under TD conditions; The heat-assisted magnetic recording (HAMR) read / write head of claim 1 .

4. the pair of active bumper pads both have triangular surfaces extending proximally rearward from the ABS and passing over an inductive magnetic coil element, whereby each of the active bumper pads absorbs heat generated by the magnetic coil element during a write process; The heat-assisted magnetic recording (HAMR) read / write head of claim 1 .

5. each of the active bumper pads is identical in shape to the other active bumper pads, such that when thermally activated, each active bumper pad creates a protrusion from the other active bumper pads, thereby symmetrically changing the response of the slider under TD conditions; The heat-assisted magnetic recording (HAMR) read / write head of claim 1 .

6. During a TD, the pair of thermally activated bumper pads move the closest point of the slider ABS to the disk media from the HDI to the activated bumper pads, improving both TD detection and head reliability. The heat-assisted magnetic recording (HAMR) read / write head of claim 1 .

7. adjusting the size and shape of each active bumper pad to accommodate different head designs, writing conditions, and head manufacturing processes; The heat-assisted magnetic recording (HAMR) read / write head of claim 1 .

8. The thermally assisted magnetic recording (HAMR) read / write head of claim 1 is mounted on a slider; the slider is aerodynamically configured to maintain the HAMR read / write head at a predetermined flying height when the slider is flying above a rotating magnetic-recording disk, and a thermal protrusion on the active bumper pad controls the minimum flying height point of the slider during TD. Slider-mounted HAMR read / write head.

9. The thermal protrusion caused by the active bumper pad increases the area of ​​the slider ABS closest to the disk media during the TD, thereby allowing the HDI to uniformly approach the disk media and making the TD event more easily detected by the HDI.

2. The slider-mounted HAMR read / write head of claim 1.

10. The active bumper pad moves the point of closest approach to the TD of the slider ABS from the exposed sensitive area on the ABS to a larger shield, thereby improving head reliability.

10. The slider-mounted HAMR read / write head of claim 9.

11. The active heater bulge reduces the temperature rise of the reader by 12% during HDI, thereby improving slider reliability.

10. The slider-mounted HAMR read / write head of claim 9.

12. The active heater bulge creates a heater spacing that can be varied from 0 to 1 nanometer by fine tuning HDI / TD wear conditions.

10. The slider-mounted HAMR read / write head of claim 9.

13. The active heater bulge has an area of ​​the TD of 55 μm ２ to 88 μm ２ , thereby generating sufficient vibration to detect TD or HDI.

10. The slider-mounted HAMR read / write head of claim 9.

14. The heater design reduces heater-induced transducer temperature rise 9. The slider-mounted HAMR read / write head of claim 8.

15. The heater design reduces the distance between peaks of the heater-induced transducer temperature rise.

9. The slider-mounted HAMR read / write head of claim 8.

16. The heater element has a plurality of recesses that create heater ridges containing an equal number of nanobumpers.

10. The slider-mounted HAMR read / write head of claim 9.

17. The transducer spacing during touchdown (TD) is adjusted by the bulge shape and nanobumper height.

10. The slider-mounted HAMR read / write head of claim 9.

18. (a) a HAMR device according to claim 1; (b) a suspension that elastically supports the HAMR device and includes a flexure to which the HAMR device is joined, and a load beam that is connected to the flexure at one end and to a base plate at the other end; A head gimbal assembly (HGA) comprising:

19. (a) the HGA according to claim 18; (b) a magnetic recording medium facing a slider provided with the magnetic reproducing head structure; (c) a spindle motor that rotates to drive the slider; (d) a device for supporting the slider and positioning the slider relative to the magnetic recording medium; A magnetic recording device comprising:

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