JP5833061B2 - Apparatus, method and write head - Google Patents

Description

The present invention relates to an apparatus, a method, and a write head.
Related Patent Literature This is a continuation of US Patent Application No. 13 / 687,282, filed November 28, 2012, and further, provisional patent application serial number filed July 27, 2012. Claim the benefits of 61 / 676,835. On the other hand, the priority is 35U. S. C. Claimed in accordance with §119 (e), both of which are hereby incorporated by reference in their entirety.

Overview The example described herein is directed to a thermally assisted magnetic recording device. In one embodiment, an apparatus includes a write element configured to apply a magnetic field to write data on a portion of a thermally assisted magnetic recording medium in response to an energizing current. Including. The energy source is configured to heat a portion of the medium that is magnetized by the writing element. The preheat conduction current is applied to the write element during an interval before writing data to the portion of the media. The preheating conduction current does not write data to the medium, and puts at least one of the writing element and the driver circuit system in a thermal equilibrium state before writing data on the portion.

  In other embodiments, the method and apparatus facilitates determining that data is to be written to a portion of a thermally assisted magnetic recording medium. The preheat conduction current is applied to the write element during an interval before writing data to the portion of the media. The writing element applies a magnetic field to the medium in response to the preheating conduction current. The preheating conduction current does not write other data to the medium, and puts at least one of the writing element and the driver circuit system into a thermal equilibrium state before writing data on the portion. After this interval, an energy source configured to heat the portion of the media is energized and an energizing current is applied to the write element to write data to the portion of the media.

  In another embodiment, heat applied to the recording medium from the write head is removed while the thermally assisted magnetic recording medium is not being written. This heat makes it easy to write to the recording medium. When the recording medium is not being written, power is applied to the write coil of the write head to control the spacing between the write head and the recording medium.

  These and other features and aspects of the various embodiments will be understood in view of the following detailed discussion and the accompanying drawings.

  The following discussion refers to the following figures, in which the same reference numbers may be used to identify similar or identical components in multiple figures.

FIG. 3 is a side view of a slider according to an exemplary embodiment. FIG. 5 is a timing diagram illustrating preheating of a slider according to an exemplary embodiment. FIG. 2 is a block diagram of an apparatus according to an exemplary embodiment. 6 is a flowchart illustrating a procedure according to an exemplary embodiment. 6 is a flowchart illustrating a process according to various embodiments. FIG. 2 is a cross-sectional view of a write head according to an exemplary embodiment. 6 is a graph illustrating protrusions induced by a write coil, in accordance with an exemplary embodiment. 6 is a flowchart illustrating a procedure according to an exemplary embodiment.

DETAILED DESCRIPTION This disclosure relates to the use of preheating of write elements (eg, write coils) and associated circuitry to achieve thermal balance in thermally assisted magnetic recording (HAMR) devices. In one embodiment, the writer coil and driver circuitry preheating is controlled externally, for example via a system controller. The same result can also be achieved in the preamplifier via a firmware controlled register that affects the internal preamplifier circuit. Furthermore, other permutations of control can be envisaged. The writer coil current is applied prior to the actual write operation, thereby simplifying the fly height control for writer protrusion during active write operations.

  In HAMR devices, sometimes referred to as thermally assisted magnetic recording (TAMR) devices, thermal energy is applied to magnetic recording media to overcome the superparamagnetic effect that limits the area data density of conventional magnetic media. Used in the context of a magnetic field applied to a (eg hard drive disk). In the HAMR recording device, information bits are recorded on the storage layer at a high temperature. The heated area in the storage layer determines the data bit dimension, and the linear recording density is determined by the magnetic transition between the data bits.

  In order to achieve the desired data density, HAMR recording heads (eg, sliders) direct optical energy from an energy source such as a laser diode to direct, concentrate and convert optical components that heat on the recording medium. Including. The HAMR media hotspot may need to be smaller than half the wavelength of light available from an economical energy source (eg, a laser diode). Because of what is known as the diffraction limit, optical components cannot focus light on this scale. One way to achieve a small confined hot spot is to use an optical near field transducer (NFT) such as a plasmonic optical antenna. The NFT is designed to have surface plasmon resonance at the designed light wavelength. In resonance, a high electric field surrounds the NFT by the collective vibration of electrons in the metal. A portion of the electric field is tunneled into the storage medium and absorbed, raising the temperature of the medium locally above the Curie point for recording. Without the presence of thermal energy, the media will be below the Curie point and no effective erasure or remagnetization will occur in the presence of a magnetic field from the writer. However, it is implicitly understood that magnetic transitions are defined (magnetically frozen) at temperatures below the Curie temperature.

  HAMR drives may use lasers and near-field transducers to heat the media and assist in the recording process. Due to the inefficiency of the optical transmission path, the laser and near field transducer also heat the head / slider. This heating can arise from the NFT, the light delivery optics, and / or the laser itself. The energy absorbed by these components can be converted to heat, which is conducted to the surrounding material. This heating can cause the writer element to project via thermal expansion of the slider (ie, fly closer to the disk) or change the shape of the slider to change the air bearing characteristics, thereby changing the head-medium spacing (HMS). Can lead to fluctuations. An example of this is shown in FIG. 1, which shows a side view of a slider 102 according to an exemplary embodiment.

  A technique known as pulsing is used for controlling the laser in some HAMR drive embodiments. The pulsing flashes the laser in synchronism with the magnetic transition from the writer coil. The timing of pulsing with respect to the magnetic transition can affect the bit error rate of the recording system. The timing of these magnetic transitions is affected by electrical delays through the preamplifier driver circuitry, and these delay times may be affected by the temperature of the circuitry. One further result of the early and / or continuous application of the writer coil current is to bring the driver circuitry into thermal equilibrium so as to minimize timing delay shifts.

  The slider 102 is coupled to an arm (not shown) by a suspension 104, but the suspension 104 is attached to a gimbal 106 that allows some relative movement between the slider 102 and the suspension 104. The slider 102 includes a read / write transducer 108 held near the surface 110 of the magnetic recording medium, eg, disk 111, at the trailing edge. When the slider 102 is positioned on the surface 110 of the disk 111, the flying height 112 is maintained between the slider 102 and the surface 110 by the downward force of the suspension 104. This downward force is balanced by an air cushion that exists between the surface 110 and the air bearing surface (ABS) 103 of the slider 102 when the disk 111 is rotating.

  To ensure consistent performance, a predetermined spacing between the writer element and reader element and the medium 112 over a range of cylindrical disk positions during both read and write operations. It is desirable to maintain. Region 114 is the “near point” of slider 102, which is generally understood to be the closest point of contact between slider 102 and magnetic recording medium 111 and generally defines HMS 113. Heating from HAMR optics can affect HMS 113.

  Heating from the writer coil current can affect the HMS 113. In this example, the variation in shape may be induced in whole or in part by an increase or decrease in the temperature of region 114 due to the different thermal expansion characteristics of the respective materials surrounding region 114. This is indicated in FIG. 1 by a dotted line representing the variation in the shape of region 114. Exemplary HAMR components that induce these temperature changes include a laser 119, waveguide 121 and NFT 123 mounted on top. In order to control the spacing, many printheads further include one or more internal heaters (not shown) to carefully apply heat. In one exemplary embodiment, slider 102 includes two heaters. The first further heater is in proximity to the reader element and is called the reader heater. The second heater is close to the writer element and is called a writer heater.

  The slider 102 may include a resistance temperature sensor 120 located at or near the region 114. This sensor 120 has a temperature coefficient of resistance (TCR) that allows a highly accurate measurement of the temperature (or temperature change) in region 114 and is therefore sometimes referred to as a TCR sensor. TCR sensor 120 is coupled to control circuitry 122. The control circuitry 122 communicates with the sensor 120 along with the other electrical components of the slider 102. Two or more TCR sensors 120 may be used, for example, located at locations physically separated from each other. The plurality of sensors 120 are wired away from each other or together (eg, in series or in parallel) to reduce the number of connections required for the slider 102.

  In a HAMR recorder, the four protrusions each have different time constants during writing at ABS: writer heater protrusion (˜100 μs); writer coil protrusion (˜100 μs); NFT protrusion; (˜1 μs us followed by ˜100 μs); It may need to be managed with laser heating (˜1000 μs) of the slider. The conventional HAMR preamplifier turns on the writer coil simultaneously with the laser. This results in an interaction between the writer coil and the NFT induced protrusion. Due to the high coercivity of HAMR media, the head cannot write to the media unless the laser is active. This means that the writer coil current and writer heater current can be enabled prior to writing, which allows them to reach thermal equilibrium by the time writing occurs. This means that only the thermal projecting dynamics from the laser need to be considered because everything else is in thermal equilibrium.

  Thus, a preamplifier according to an exemplary embodiment may be modified to apply current through the writer before the sector is written. In such a configuration, the writer coil current can be kept on or turned off in the sector gap and servo gate (SG) as long as the laser is off during those times. It may be preferable to turn off the writer current between SGs to avoid coupling into the readhead and affecting the servo system.

  The preheating current applied to the writer coil can be alternating current (AC) or direct current (DC). The AC signal may avoid any pitfalls with a DC magnetic field, but a DC signal is required if the writer coil current remains on during SG to reduce electrical noise. There may be. For example, US Pat. No. 7,088,537 by Cronch et al. Describes a degaussing mode in a disk drive preamplifier. The degaussing mode circuitry in the preamplifier (etc.) can be used as a control source for AC current for this purpose. The AC signal may be generated internally within the preamplifier and / or externally by a system controller, eg, a system read channel (SRC) that is part of a hard drive main controller application specific integrated circuit (ASIC). . Either strategy is acceptable and both are shown here.

  Referring now to FIG. 2, a timing diagram shows an example of how a printhead may be preheated according to an exemplary embodiment. The diagram is divided into four types of signals: timing control 202, laser and channel writer control 204, firmware control 206 and physical current 208.

  As indicated by trace 216, the firmware writes to the preamplifier register at time 201 to set the current for the laser bias and writer coil prior to the write operation. The firmware enables preheating in a sufficient amount of time so that the writer heater current 238 and writer coil current 228 cause the affected components to reach thermal equilibrium. The preheat time for the writer coil is indicated by interval 203 in FIG.

  The firmware may optionally enable a new preamplifier function that uses an internally generated AC or DC signal to send current to the writer coil. An example of this can be seen in FIG. 3, which is a block diagram of an apparatus 300 according to an exemplary embodiment. The device 300 includes a system controller 317 that may include one or more logic circuits that control the functionality of the device 300. The system controller 317 receives a command via the host interface 303. In response to a write command from host interface 303, system controller 317 causes write preamplifier assembly 301 to write data to magnetic data storage medium 305.

  The preamplifier assembly 301 includes a writer coil driver circuitry 302 that drives one or more write coils 304 included in the recording head 318. The write coil 304 forms a magnetic field in response to the application of current. Preamplifier 301 is controlled via multiplexer 306 by combining write enable line 308 and write data signals (WDATA +/−) 309, 310 among other control signals not shown. The apparatus includes firmware 315 that allows preamplifier assembly 301 to send current to writer coil 304 using internally generated AC or DC signals in the context of system controller 317. The AC signal may be generated by an internal oscillator 320, such as that used for degaussing operations. This alleviates the need to control write data signals (WDATA +/−) 309, 310 to perform preheat signal transmission. To minimize crosstalk between the writer line and the leader line on the flexible line (FOS) on the suspension, the writer coil preheating is turned off during servo (eg during period 205 in FIG. 2). Also good.

  Apparatus 300 further includes an energy source 316 (eg, a focused laser diode output) that heats a portion of medium 305 that is currently magnetized by write coil 304. The energy source 316 is enabled via a system controller 317 (eg, laser enable line 224 in FIG. 2) to heat a portion of the media 305 during recording. For purposes of this discussion, a “media portion” may include an area that is larger than the signal bits of the data being written. For example, the portion may include multiple hard drive sectors, for example, when traversing a servo mark, writing may be paused and resumed during the writing of the portion.

  As described herein, activation of the write coil 304 generally requires no other data to be written to the media 305 when the energy source 316 is not energized (eg, local magnetic orientation in the media). There is no significant change in) and no existing data is erased. It should be noted that in some designs utilizing a semiconductor laser diode as an energy source, it is desirable to have a small current that does not write but still flows through the laser diode. For the purposes of this disclosure, unless the laser is lasing sufficiently to raise the media temperature near or above its Curie point, the laser will still be non-existent even when a small bias current is present. It can be considered as being energized. Thus, in some cases, the write coil 304 is activated by an energizing current and activated while the write element (eg, write coil 304, write pole and Related components) may be in thermal equilibrium. To accomplish this, energy source 316 and write coil 304 may be controlled via separate signals.

  Referring again to FIG. 2, signals 214, 224 and 234 are generally considered part of the system controller read channel writer and laser control. The channel controls the writer enable (W / Rn) line (signal 234) along with the write data line (signal 214) and the laser enable line (signal 224). The channel enables the laser whenever it wants to write data to the disk. The laser enable line is not the same as W / Rn because it may be necessary to refrain from such writing when it is not necessary to write to successive sectors. The separation of these lines also takes into account the ability for pulsed control and writer preheating. In continuous writing mode, laser control is a logic signal. For pulsed recording, the logic gate may be replaced with high bandwidth laser data.

  Signals 218, 228 and 238 are physical currents output to the laser, writer coil and heater, respectively. The laser current 218 shown is for a pulsed laser. If this is a CW implementation, the laser current will switch on at the start of the sector and remain stable for the duration. Data is written to the disk only when the laser current 218 is sufficient for lasing. In the absence or reduced laser current 218, the magnetic field from the head is insufficient to mark the disk. However, without the writer current 228, the laser will still erase the disk.

  In FIG. 4, a flowchart illustrates a procedure for preheating a write element according to an exemplary embodiment. At 410, it is determined that data is written to a portion of the HAMR media (eg, by a system controller). At 420, a preheat conduction current is applied to the write element during an interval before writing data to the portion of the media. The preheat energization current does not write data to the media and puts the writer in thermal equilibrium (which is understood to include maintaining existing thermal equilibrium) before writing data onto the portion. After this interval, an energy source (eg, a laser diode) is energized at 430. The energy source is configured to heat the portion of the media and an energizing current is applied to the write element to write data to the heated portion of the media.

  According to various implementations, HAMR may be used in combination with recording on bit patterned media (BPM). The BPM format may include various fields such as timing recovery and servo fields that are embedded in the data area of the media. According to various implementations, the timing field embedded in the data area of the medium is read while an ongoing write operation is paused. Hold the writer coil current as the write pole crosses these fields to remove the formatting overhead associated with the non-zero time it takes to turn the write current off and back on while reading the timing fields It may be advantageous to do.

  In addition, bit patterned media implementations may require precise timing of magnetic field transitions and / or laser pulsing synchronized with bits on the media. The timing of these magnetic field transitions is affected by electrical delays through the preamplifier driver circuitry, and these delay times may be affected by the temperature of the circuitry. One further result of the early and / or continuous application of the writer coil current is to bring the driver circuitry into thermal equilibrium so as to minimize timing delay shifts.

  According to various implementations, the writer turn-on / turn-off overhead is reduced by reading the timing field while leaving the DC write current on. For example, when the timing field is patterned so that unipolar magnetization can be used, the write transition overhead is the same when the writer pole traverses the unipolar field with the laser off or on. It can be removed by writing a polar DC. In some cases, however, bipolar written fields such as run-out correction values may be corrupted by DC writing. Thus, in some cases it may be useful to turn off the laser when reading the timing field to prevent overwriting and / or corruption of data.

  It may be useful to eliminate the writer turn-on / turn-off overhead and achieve faster thermal balance by leaving the DC write current and laser on while on a unipolar BPM servo field. However, in some cases, there may be bipolar written information fields (such as run-out correction values) that will be corrupted by DC writing in or against these servo fields. unknown. Thus, in a HAMR + BPM system, it would be advantageous to turn off the laser in a unipolar field, allowing the write current to remain on without risk of damaging the bipolar information field.

  In FIG. 5, a flow chart illustrates a process for preheating a write element in accordance with the embodiments described herein. At 510, it is determined that data is written to a portion of the HAMR media. At 520, a data write operation to the thermally assisted magnetic recording medium is initiated. At 530, the write operation is suspended for an interval. According to various implementations, various fields (eg, timing field or servo field) are read during the interval. At 540, a preheat energization current is applied to the write element, the write element applies a magnetic field to the medium in response to the preheat energization current, and the preheat energization current does not write data to the medium and the writer is in thermal equilibrium. Put it in a state. After this interval, at 550, an energy source (eg, a laser diode) is energized. In some cases, the writing operation is resumed upon completion of the interval and the light source is energized again. The resumption of the writing operation may include energizing the light source.

  Referring now to FIG. 6, a cross-sectional view shows components of a read / write converter 600 according to an exemplary embodiment. This figure shows a portion of the slider near the near point region 601. In this figure, the x direction is downtrack with respect to the medium and the z direction (perpendicular to the page plane) is the crosstrack direction. Read sensor 602 is near ABS 607. The read sensor may include a magnetoresistive stack and a shield. Reader heater 604 may be implemented to adjust the local spacing between read sensor 602 and media surface 603.

  The write pole 606 may include a ferromagnetic structure that extends to the ABS 607. Write coil 608 is energized to generate a magnetic field in write pole 606 that extends to media surface 603. The slider may be configured for perpendicular recording, where the magnetic orientation is perpendicular to the media surface 603 (in this figure, it is oriented along the y direction). Thus, the slider may include one or more return poles 610 and 612 that facilitate the vertical orientation of the magnetic field of the recorded data, as well as the particular configuration of layers in the media 605. The spacer 614 may be disposed between the reading portion and the writing portion of the slider.

  To write to the HAMR media 605, the slider includes a waveguide 616 that extends toward the ABS 607. Waveguide 616 conducts light to near field transducer (NFT) 618 located near the tip of write pole 606 at ABS 607. NFT 618 facilitates directing a beam of electromagnetic energy to media surface 603 during a write operation. The energy forms a small hot spot at the media surface 603 with a reduced coercivity, allowing the magnetic field generated from the write pole 606 to affect the magnetic orientation within the hot spot.

  In some configurations, the spacer 614 (or some other region close to the write pole 606 and / or the return pole 610, 612) is further from the head of the write pole 606 independently of that of the read sensor 602. A heater may be included to adjust the spacing to the medium. However, in this example, the slider does not include a separate heater. Alternatively, the write coil 608 can be activated to provide heat that may normally be provided by its separate heater. Any magnetic field generated by this activation of coil 608 will not change the data on media 605 unless the light source is activated to heat media surface 603.

  The illustrated example shows that the reader heater 604 is used with a write coil 608 to independently control the clearance from the read and / or write portion heads of the transducer to the media. In one example, the reader heater 604 controls the head-medium spacing of the read sensor 602 and the write coil 608 controls the head-medium spacing of the write pole 606 alone or in combination with the reader heater 604. In other examples, a different heater (eg, one that is located near the write portion of the transducer 600) may be used to control the head-medium spacing of the write pole 606, and the write coil Assuming that activation of 608 causes little or no interference with the read sensor 602, the write coil 608 (alone or with a different heater) is used to adjust the head-medium spacing of the read sensor 602. .

  Referring now to FIG. 7, a graph 700 shows an example of ABS protrusion of a HAMR slider according to an exemplary embodiment. In this graph 700, the ABS contour is represented as the spacing / clearance between the ABS and the media along the vertical axis and the downtrack position along the horizontal axis. Downtrack region 702 represents a near point of the ABS (eg, near a read or write transducer). Trace 704 represents an outline at ambient temperature where power is not applied to either the heater or the write coil. Trace 706 is the contour when power is supplied only to the heater, and trace 708 represents the contour when the heater and write coil are energized; trace 710 is the heater, write coil and laser all Represents the contour when energized.

  As the difference between traces 706 and 708 shows, the write coil alone may be able to generate enough heat to cause sufficient protrusion. Further, the write coil can be used in combination with one or more heaters operating together (instead of dual heaters operating separately) to write the magnetic head at different times and / or in different states of the slider. The desired clearance of both the part and the reading part may be achieved. For example, the write coil current can be set to a value that maximizes performance (at a constant head-medium spacing), and then in parallel, a dedicated heater can be used to bring the clearance to the desired value. This may be useful during a write operation because activation of the write coil for writing will cause some predictable amount of protrusion and the dedicated heater can fine tune the clearance. It is.

  Various features of the read / write head may be designed in such a way as to fully utilize the writer protrusion as a mechanism for head-medium spacing control. For example, for the purpose of affecting the head-medium spacing, it can be envisaged to increase the resistance of the write coil to induce higher temperatures. It can be envisaged to design the write coil and / or the peripheral region with a higher coefficient of thermal expansion to increase the protrusion. In another example, it is conceivable to design features designed to cool the write coil in a manner that reduces cooling in the coil and in the near area, for example, using a material with lower thermal conductivity. Can be.

  With reference now to FIG. 8, a flow chart illustrates a procedure in accordance with an illustrative embodiment. In this procedure, a first path 802 is taken when a heat-assisted magnetic recording medium has not been written. In such a case, at 804, heat from the write head to the recording medium is removed. This may involve turning off or disengaging a device that applies heat (eg, laser, optical path). When the medium is not being written, power is applied to the write coil of the write head at 806 to control the spacing between the write head and the recording medium. This may include the spacing between the read elements and / or write elements of the write head. Optionally, power may be applied to the dedicated heater at 807 to control the spacing in parallel with power application 806 to the write coil.

  A path 808 represents a head-to-disk clearance operation that occurs when the medium is being written, and at least a heat source (eg, laser light) is applied to the recording medium. At 810, heat is applied to the recording medium from the write head. One or both of operations 812 and 814 may be performed to adjust the clearance (eg, clearance between the media and the read head and / or write pole) while the media is being written. Act 812 involves applying power to the write coil to record data and control the spacing between the write head and the medium. Act 814 involves applying power to a dedicated heater to control the spacing between the write head and the media. This may be the same dedicated heater used in block 807.

  The apparatus includes a write element configured to magnetize a portion of the thermally assisted magnetic recording medium in response to an energizing current during a write operation; and a portion of the medium that is magnetized by the write element An energizing current applied to the writing element and energizing the writing element during an interval in which the writing operation is suspended and the energy source is de-energized. The application of current does not write any other data to the medium, and the energization current causes the write element and / or driver circuitry to be in thermal equilibrium before writing data on that portion of the medium. The energy source may include a laser diode. The write operation may be resumed at the end of the interval. The resumption of the writing operation may involve energizing the energy source. The device may be configured to read the timing field during the interval.

  The foregoing description of the exemplary embodiments is presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the examples to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. Any or all features of the disclosed embodiments may be applied individually or in any combination, they are not meant to be limiting, but are purely exemplary. The scope of the invention is not limited in this detailed description, but is intended to be determined by the claims.

  305 heat assisted magnetic recording medium, 304 writing element, 316 energy source

Claims (16)

A write element configured to apply a magnetic field to write data on a portion of the thermally assisted magnetic recording medium in response to the energized current;
An energy source configured to heat the portion of the medium that is magnetized by the write element;
A preheating energization current is applied to the write element during an interval before writing the data to the portion of the medium, the energy source is not energized during the interval, and the preheating energization current is Applying a magnetic field to the medium, the magnetic field being sufficient for writing to the medium when the medium is heated by the energy source, but other data is not obtained because the energy source is not energized. Without writing to the medium, the preheating energization current causes at least one of the write element and driver circuit system to be in thermal equilibrium before writing the data on the portion,
The apparatus, wherein the preheating energization current is turned off during the servo if a servo period is included in the interval. Said energy source including a laser diode device of claim 1.   The apparatus according to claim 1, wherein the preheating conduction current includes an alternating current.   The apparatus of claim 3, wherein the alternating current is controlled by a system controller.   4. The apparatus of claim 3, wherein the alternating current is controlled by a preamplifier that drives the writing element.   The apparatus according to claim 1, wherein the preheating conduction current includes a direct current.   The apparatus of claim 1, wherein the medium comprises a bit patterned medium.   The apparatus of claim 7, wherein a unipolar field is traversed during the interval, the energizing current is direct current, and the energy source is energized during the interval.   8. The apparatus of claim 7, wherein a bipolar field is traversed during the interval, and the energy source is not energized during the interval. Determining that data is written to a portion of the thermally assisted magnetic recording medium;
Applying a preheating energization current to a writing element during an interval before writing the data to the portion of the medium, wherein the preheating energization current applies a magnetic field to the medium, and the magnetic field Is sufficient for writing to the medium when the medium is heated by an energy source, but because the energy source is not energized, no other data is written to the medium and the preheating energizing current is the at least one write element and driver circuitry prior to writing the data onto the portion to the thermal equilibrium state; Furthermore,
After the interval, and energizing the energy source configured to heat the portion of the medium, by applying a current supplied to said write elements, comprising the steps of writing the data to the portion of the medium Including
The method wherein the preheat energization current is turned off during the servo if a servo period is included in the interval. A writing head,
An apparatus configured to facilitate writing to the magnetically assisted magnetic recording medium by applying heat by an energy source ;
A write coil configured to apply a magnetic field to the magnetic recording medium in response to application of power, wherein the writing coil is at least when the heat is removed from the magnetic recording medium And configured to control the spacing between the write head and the magnetic recording medium in response to the application of power to the write coil,
A preheating energization current is applied to the write coil during a time interval before writing the data to the portion of the medium, and the energy source is not energized during the time interval, and the preheating energization An electric current applies a magnetic field to the medium, which is sufficient for writing to the medium when the medium is heated by the energy source, but the energy source is not energized and other Do not write data to the medium,
The write head, wherein the preheating energization current is turned off during the servo if a servo period is included in the time interval.   The write head of claim 11, wherein the device for providing heat includes a near-field transducer, and the device further includes an optical device configured to apply energy to the near-field transducer.   12. The application of power to the write coil causes a heat-induced protrusion of the write head that changes the spacing between the write head and the magnetic recording medium. Or the writing head according to 12.   14. The application of any one of claims 11 to 13, wherein the application of the power to the write coil is used in place of a heater dedicated to controlling the spacing for the write head transducer. The writing head described.   The write coil is further configured to record data on the magnetic recording medium and to control the distance between the write head and the magnetic recording medium during writing to the magnetic recording medium. 15. The write head according to any one of claims 11 to 14, wherein:   16. The write head of any one of claims 11 to 15, wherein the magnetic field does not write data to the magnetic recording medium when the heat is removed from the magnetic recording medium.