JP2007115296A - Magnetic head and magnetic disk apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic head having an excellent adjacent track erasing (ATE) property, and a magnetic disk apparatus of a single recording system of high track pitch and high recording density. <P>SOLUTION: A write-head 40 has an upper part magnetic pole end part 1 and a lower part magnetic pole layer 4, and a part of the lower part magnetic pole layer 4 is trimmed and made a lower part magnetic pole notch part 2. A write-gap layer 3 consisting of a non-magnetic object exists between the upper part magnetic pole end part 1 and the lower part magnetic pole notch part 2. Then, the lower part magnetic pole part 2 is made asymmetry of left and right for a straight line X of a cross track direction passing through a center of the write-gap. Concretely, a value of trimming depth 5 of an A side of the lower part magnetic pole notch part and a value of trimming depth 6 of a B side are different. Especially, the trimming depth 5 of the A side being an inverse side of a progress direction of the write-head 40 is made larger than the trimming depth 6 of the B side being the progress direction side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic head and a magnetic disk apparatus, and more particularly to a write head configuration suitable for a single recording method.

  The magnetic disk device is indispensable in the present advanced information society as a device capable of recording a large amount of data, and is required to be able to read and write (read / write) data stably. The magnetic disk device is composed of a magnetic recording medium (magnetic disk) on which data is recorded, a magnetic head for reading and writing data, a voice coil motor for moving the magnetic head, and other circuits. The magnetic head is composed of a write head for writing data and a read head for reading data recorded on the magnetic disk.

  For example, as described in Patent Document 1, the write head has a symmetrical shape with respect to a straight line in the cross track direction passing through the center of the write gap when viewed from the air bearing surface. FIG. 8 shows a simplified view of a conventional write head as viewed from the air bearing surface. There are an upper magnetic pole tip 1 and a lower magnetic pole layer 4 made of a magnetic material, and a part of the lower magnetic pole layer 4 is trimmed to form a lower magnetic pole notch portion 2. Between the upper magnetic pole tip 1 and the lower magnetic pole notch portion 2 is a write gap layer 3 made of a nonmagnetic material. A signal is recorded on the magnetic disk by a write magnetic field generated in the write gap layer 3 portion. The trimming depth 30 of the lower magnetic pole notch portion 2 is the same on both the left and right sides, and is bilaterally symmetric.

  There is a single recording (Shingle recording) system as described in Patent Document 2 as one format for writing data. This is a system in which recording is overwritten from one track to the next track, unlike the conventional random access system. Since the track direction is narrowed while overwriting adjacent tracks, the conventional wide write head can be used to increase the recording density, which is advantageous in terms of yield and process difficulty. In addition, since it is not necessary to use a narrow track write head, there is little concern about deterioration of the writing ability accompanying narrowing of the track. It is expected to be applied to a magnetic disk apparatus for AV use that handles continuous data and has few random writes.

  On the other hand, in a magnetic disk device, an ATI (Adjacent Track Interference) characteristic and an ATE (Adjacent Track Erase) characteristic are one of important RW characteristics. Both are indicators of how much influence is exerted on adjacent tracks when a write operation is performed on a certain track. Here, ATI represents a number of times (usually about 10,000 times), and ATE represents the degree of disappearance of adjacent tracks when written once. In the magnetic disk drive, ATI characteristics are particularly important. With the recent increase in recording density, the track interval (track pitch) needs to be made very narrow. There is a need to optimize disk conditions.

JP 2003-85709 A US Pat. No. 6,185,063

In the single recording (Shingle recording) method, the signal is overwritten in only one direction in the radial direction and is not randomly written. Therefore, the ATI characteristic does not become a big problem, and the ATE characteristic which is the amount of erase at the time of writing once. It is necessary to watch. Although the erase amount when writing once is relatively small compared to the case of writing multiple times, using a wide write head is one of the main advantages in the single recording method. Invasion becomes a big problem. This is because the wider the write track width, the stronger the on-track magnetic field strength and, as a result, the larger the magnetic field leaked to the side. If adjacent tracks are erased, it becomes difficult to achieve a high recording density and thus a high recording density.
An object of the present invention is to provide a magnetic head having excellent adjacent track erase (ATE) characteristics.
Another object of the present invention is to realize a high recording density at a high track pitch in a single recording type magnetic disk apparatus.

  In order to achieve the above object, in a typical magnetic head of the present invention, a lower magnetic pole layer having a lower magnetic pole notch portion and an upper magnetic pole layer disposed so as to face the lower magnetic pole notch portion through a magnetic gap layer A top pole layer, a top pole layer connected to the top pole tip, and a conductor coil provided via an interlayer insulating layer between the top pole layer and the bottom pole layer, and the bottom pole notch portion is The trimming amount on the opposite side to the recording traveling direction in the radial direction of the magnetic disk is larger than the trimming amount on the traveling direction side.

  According to the present invention, a write head having excellent adjacent track erasing (ATE) characteristics can be realized, and a magnetic disk device having a high track pitch and a high recording density can be provided.

  First, the configuration of the magnetic head 10 to which the present invention is applied will be described with reference to FIG. The magnetic head 10 includes a reproducing head 20 formed on a substrate 50 and a write head 40 formed on the reproducing head 20 via an insulating layer 35. The reproducing head 20 has a sensor film 23 such as a GMR element formed between the lower magnetic shield layer 21 and the upper magnetic shield layer 27 via the lower gap layer 22 and the upper gap layer 26, and is laminated on both ends of the sensor film 23. The magnetic domain control layer 24 and the electrode layer 25 are provided. The write head 40 is an inductive magnetic head, and includes a lower magnetic pole layer 4, a lower magnetic pole notch portion 2 in which a part of the lower magnetic pole layer 4 is trimmed, and a nonmagnetic magnetic gap formed in the lower magnetic pole notch portion 2. Layer (write gap layer) 3, upper magnetic pole tip 1 provided to face lower magnetic pole notch portion 2 via write gap layer 3, and upper magnetic pole connected to upper magnetic pole tip 1 and serving as a magnetic yoke part And a conductor coil 16 provided between the lower magnetic pole layer 4 and the upper magnetic pole layer 12 with an interlayer insulating layer 14 interposed therebetween. The upper part of the induction type recording head 40 is covered with a hard protective layer (not shown). The magnetic head 10 is a composite magnetic head including the reproducing head 20 and the write head 40, but may be a magnetic head including only the write head 40.

  Next, the overall configuration of the magnetic disk device on which the magnetic head 10 is mounted will be described with reference to FIG. The magnetic disk device 100 includes a base 55, a spindle motor 62 fixed to the base 55, and an actuator 44. At least one magnetic disk 60 is attached to the spindle motor 62, and the actuator 44 includes a head arm 34 that swings about a pivot 45, a voice coil 47, and a magnetic circuit 48. One end of a suspension 42 is attached to the head arm 46, and the magnetic head 10 is attached to the other end of the suspension 42. A lift tab 43 is formed at the tip of the suspension 42. Further, a load / unload mechanism 70 is fixed to the base 55. By passing an electric current through the voice coil 47, the head arm 46 swings around the pivot 45, and the magnetic head 10 attached to the suspension 42 is positioned at an arbitrary position in the radial direction of the magnetic disk 60. Recording or playback is performed. The magnetic head 10 is driven by the actuator 44 when the data recording or reproduction is completed or the power of the magnetic disk device 100 is cut off, and the lift tab 43 moves up and down the ramp slope of the load / unload mechanism 70. Moved to an area.

  Here, FIG. 6 shows an example of the result of measuring ATE for various write heads. The track pitch was set to 135ktpi (188nm). A recording track was created at a specific position, and a low frequency (LF) signal was written once at a position separated by the track pitch on both the left and right sides. The value obtained by normalizing the output of the central recording track at this time with the output before writing is shown on the vertical axis. An ATE of 1 indicates that the signal has not decreased at all. The smaller the value, the greater the output decreased by the adjacent light. The ATE depends on the effective write track width, and it can be seen that the output is greatly reduced when the write track width is wide. In the case of single recording (Shingle recording), recording is performed while overwriting in one direction, so adjacent erasure is performed on only one side, and it is expected that the ATE will be better than the result of this experiment. However, when the track pitch is further reduced, or when the leakage magnetic field in the track width direction is increased using a head having a wider write width, it can be easily inferred that the signal can be largely erased.

  FIG. 7 shows the result obtained by computer simulation of the write head magnetic field distribution when viewed from the air bearing surface. It can be seen that the magnetic field leaks from the vicinity of the write gap layer 3 and spreads in the track width direction. Here, a large magnetic field distribution is seen near the base of the lower magnetic pole notch portion 2. It is considered that this is because the saturation region S is formed in the magnetic body at the base of the lower magnetic pole notch portion 2, and as a result, the leakage magnetic field strength in the vicinity thereof is increased. Reducing this large magnetic field is indispensable for improving the ATE characteristics.

  A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a simplified diagram of a light head viewed from the air bearing surface. Here, in the single recording system, directions in which the write head 40 moves in the track width direction during recording are indicated by A and B, respectively. Here, the write head 40 records a signal while overwriting from the A side to the B side. There are an upper magnetic pole tip 1 and a lower magnetic pole layer 4 made of a magnetic material, and a part of the lower magnetic pole layer 4 is trimmed to form a lower magnetic pole notch portion 2. Between the upper magnetic pole tip 1 and the lower magnetic pole notch portion 2 is a write gap layer 3 made of a nonmagnetic material. A signal is recorded on the magnetic disk by a write magnetic field generated in the write gap layer 3 portion. Here, the write head 40 is asymmetrical with respect to a straight line X in the cross track direction passing through the center of the write gap. Specifically, the values of the trimming depth 5 on the A side and the trimming depth 6 on the B side of the lower magnetic pole notch portion 2 are different. In particular, the trimming depth 5 on the A side, which is the opposite side of the traveling direction of the write head 40, is made larger than the trimming depth 6 on the B side, which is the traveling direction side of the write head 40.

  When the magnetic material at the base portion of the lower magnetic pole notch portion 2 is saturated, the magnetic field strength in the vicinity thereof is increased and the ATE characteristics are deteriorated. However, if the trimming depth is asymmetrical on the left and right, this saturation can be avoided. For example, if the trimming depth 5 on the A side that is the opposite side of the traveling direction of the write head 40 is made larger than the trimming depth 6 on the B side that is the traveling direction side of the write head 40, Even if the root portion is close to saturation, magnetic flux flows through the B-side root portion to avoid saturation, and as a result, deterioration of ATE characteristics can be prevented. Generally, when the trimming depth is increased, the write magnetic field is reduced and the leakage magnetic field to the adjacent track is also reduced, so that the A-side leakage magnetic field is also reduced. On the other hand, the leakage magnetic field on the B side is larger than that on the A side, but in the single recording method, when the write head moves from the A side to the B side, the B side signal is always overwritten and disappears. If only the A side can record without omission, there will be no problem. In addition, when the A side is shaved by milling, reattachment occurs on the opposite B side, but in single recording, the B side write head portion, which is the side of the write head traveling direction, contributes relatively little to recording. Therefore, it is difficult to become a problem. Furthermore, since only one side is deeply trimmed, re-adhesion that occurs during trimming can be reduced, and the process advantage is increased.

  By using the structure as described above, it is possible to obtain a write head having excellent ATE (adjacent track erasing) characteristics in a single recording method, and a magnetic disk device having a high track pitch and a high recording density. Can be realized.

  Next, a second embodiment of the present invention will be described. FIG. 2 shows a simplified diagram of the light head structure as viewed from the air bearing surface. The difference from the first embodiment is that the lower magnetic pole layer 4 is trimmed only from one direction 7 and the A side which is the opposite side of the traveling direction of the write head 40 has a trimming portion. The B side, which is the direction side, is not trimmed. However, the B side has a trimmed portion far from the write gap layer 3, but this portion is not related to recording on the magnetic disk. When the magnetic material at the base of the lower magnetic pole notch portion 2 is saturated, the magnetic field strength in the vicinity thereof increases and the ATE characteristic deteriorates, but only the trimming depth 5 on the A side, which is the reverse side of the direction of travel of the write head 40, increases. If the trimming on the B side which is the traveling direction side of the reverse side write head is not performed, even if the A side root portion of the lower magnetic pole notch portion 2 is close to saturation, the volume on the B side is Magnetic flux flows through the large lower magnetic pole layer 4 and saturation can be avoided. As a result, deterioration of ATE characteristics can be prevented. In general, when the trimming depth is increased, the write magnetic field is reduced and the leakage magnetic field to the adjacent track is also reduced, so that the leakage magnetic field on the A side is also reduced. On the other hand, on the B side, there is no lower magnetic pole notch portion, so proper recording cannot be performed. However, in the single recording method, when the write head moves from the A side to the B side, the B side signal is always overwritten and disappears. If only the A side can record without omission, there will be no problem. Further, since trimming is performed deeply only on one side, re-adhesion that occurs during trimming can be reduced, and the superiority of the process is increased. In particular, since the trimming on the B side is not performed in this structure, the redeposition on the A side, which is the opposite side of the traveling direction of the write head, which is greatly related to the recording characteristics can be reduced, which is advantageous in terms of process.

  By using the structure as described above, a write head having excellent ATE (adjacent track erasure) characteristics can be obtained in a recording method using single recording, and a magnetic disk device having a high track pitch and a high recording density. Can be realized.

  Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 3 shows a simplified diagram of the top pole tip 1 when the write head is viewed from above. Here, in the single recording method, directions in which the write head moves in the track width direction during recording are indicated by A and B, respectively. Here, the head records signals while overwriting from the A side to the B side. The top pole tip 1 made of a magnetic material is asymmetrical when viewed from above. Specifically, the lengths of the flare point 8 on the A side and the flare point 9 on the B side are different. In particular, the flare point 8 on the A side is longer than the flare point 9 on the B side. In general, when the flare point is increased, the write magnetic field is reduced and the leakage magnetic field to the adjacent track is also reduced, so that the leakage magnetic field on the A side is also reduced. On the other hand, the leakage magnetic field on the B side is larger than that on the A side. However, in the single recording system, when the write head moves from the A side to the B side, the B side signal is always overwritten and disappears. If only one can record without omission, there will be no problem.

  By using the structure as described above, a write head having excellent ATE (adjacent track erasing) characteristics can be obtained in a recording method using single recording (Shingle recording), and a high recording density with a high track pitch. The magnetic disk device can be realized.

FIG. 3 is a simplified view seen from the air bearing surface of the magnetic head according to the first embodiment of the invention. FIG. 6 is a simplified view seen from the air bearing surface of a magnetic head according to a second embodiment of the present invention. It is the simplified view seen from the air bearing surface of the magnetic head by the 3rd example of the present invention. 1 is a configuration diagram of a composite magnetic head in which a magnetic head and a reproducing head according to an embodiment are combined. FIG. 1 is a configuration diagram of a magnetic disk device equipped with a magnetic head according to an embodiment. FIG. It is the figure which arranged an example of the result of having performed ATE measurement using various heads to the effective write track width. It is the figure which showed an example of the computer simulation result of the write magnetic field distribution near the write gap of the conventional magnetic head. It is the simplified view which looked at the conventional light head from the air bearing surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Upper magnetic pole front-end | tip, 2 ... Lower magnetic pole notch part, 3 ... Write gap layer, 4 ... Lower magnetic pole layer, 5 ... Trimming depth (A side), 6 ... Trimming depth (B side), 7 ... Milling direction , 8 ... Flare point (A side), 9 ... Flare point (B side), 10 ... Magnetic head, 12 ... Upper magnetic pole layer, 14 ... Interlayer insulating layer, 16 ... Conductor coil, 20 ... Reproducing head, 21 ... Lower magnetism Shield layer, 22 ... lower gap layer, 23 ... sensor film, 24 ... magnetic domain control layer, 25 ... electrode layer, 26 ... upper gap layer, 27 ... upper magnetic shield layer, 35 ... insulating layer, 40 ... write head, 42 ... Suspension, 43 ... Lift tab, 44 ... Actuator, 45 ... Pivot, 46 ... Head arm, 47 ... VCM, 48 ... Magnetic circuit, 50 ... Substrate, 55 ... Base, 60 ... Magnetic disk, 62 ... Spind Motor, 70 ... load / unload mechanism, 100 ... magnetic disk device.

Claims (10)

  A lower magnetic pole layer having a lower magnetic pole notch portion; an upper magnetic pole tip portion disposed through a magnetic gap layer facing the lower magnetic pole notch portion; an upper magnetic pole layer connected to the upper magnetic pole tip portion; A magnetic head comprising a conductor coil provided between an upper magnetic pole layer and the lower magnetic pole layer via an interlayer insulating layer, and the shape of the air bearing surface of the lower magnetic pole notch portion is asymmetrical to the left and right.   2. The magnetic head according to claim 1, wherein the lower magnetic pole notch portion has different trimming amounts on the left and right sides.   The magnetic head according to claim 1, wherein the lower magnetic pole notch portion has a trimming portion on one side of a portion facing the tip portion of the upper magnetic pole.   2. The magnetic head according to claim 1, further comprising a reproducing head on a side of the lower magnetic pole layer opposite to the side on which the upper magnetic pole layer is disposed.   A lower magnetic pole layer having a lower magnetic pole notch portion; an upper magnetic pole tip portion disposed through a magnetic gap layer facing the lower magnetic pole notch portion; an upper magnetic pole layer connected to the upper magnetic pole tip portion; A magnetic head comprising: a conductor coil provided between an upper magnetic pole layer and the lower magnetic pole layer via an interlayer insulating layer; and a shape on an upper surface of the upper magnetic pole tip is asymmetrical.   6. The magnetic head according to claim 5, wherein a flare point of the upper magnetic pole tip is different between right and left.   6. The magnetic head according to claim 5, further comprising a reproducing head on a side of the lower magnetic pole layer opposite to the side on which the upper magnetic pole layer is disposed.   In a single recording type magnetic disk apparatus for recording in one direction while overwriting a track end with a magnetic head on a magnetic disk, the magnetic head includes a lower magnetic pole layer having a lower magnetic pole notch portion, and the lower magnetic pole notch An upper magnetic pole tip disposed opposite to the portion via a magnetic gap layer; an upper magnetic pole layer connected to the upper magnetic pole tip; and an interlayer insulating layer between the upper magnetic pole layer and the lower magnetic pole layer. The lower magnetic pole notch portion has a trimming amount on the opposite side to the recording traveling direction in the radial direction of the magnetic disk larger than the trimming amount on the traveling direction side. Magnetic disk unit.   9. The magnetic disk according to claim 8, wherein the lower magnetic pole notch portion has a trimming portion on the opposite side to the recording traveling direction in the radial direction of the magnetic disk at a portion facing the tip portion of the upper magnetic pole. apparatus.   9. The magnetic disk drive according to claim 8, further comprising a reproducing head on a side of the lower magnetic pole layer opposite to the side on which the upper magnetic pole layer is disposed.

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