1. Field of the Invention
The present invention relates to a thin film magnetic head having at least an inductive magnetic transducer for recording and a magnetic recording apparatus on which the thin film magnetic head is mounted.
2. Description of the Related Art
In recent years, in association with increase in areal density of a magnetic recording medium (hereinbelow, simply called “recording medium”) such as a hard disk, improvement in performance of a thin film magnetic head to be mounted on a magnetic recording apparatus such as a hard disk drive (HDD) is demanded. Known recording methods of a thin film magnetic head are, for example, a longitudinal recording method in which the orientation of a signal magnetic field is set to an in-plane direction (longitudinal direction) of a recording medium and a perpendicular recording method in which the orientation of a signal magnetic field is set to a direction orthogonal to the surface of a recording medium. At present, the longitudinal recording method is widely used. However, when a market trend accompanying improvement in areal density of a recording medium is considered, it is assumed that, in place of the longitudinal recording method, the perpendicular recording method will be regarded as a promising method in future for the following reason. The perpendicular recording method has advantages such that high linear recording density can be assured and a recorded recording medium is not easily influenced by thermal fluctuations.
A thin film magnetic head of the perpendicular recording method has, mainly, a thin film coil for generating a magnetic flux for recording and a magnetic pole layer generating a magnetic field (perpendicular magnetic field) for magnetizing a recording medium in a direction orthogonal to its surface on the basis of the magnetic flux generated by the thin film coil. In the thin film magnetic head of the perpendicular recording method, the recording medium is magnetized by the perpendicular magnetic field generated in the magnetic pole layer and information is magnetically recorded on the recording medium.
Some modes of the structure of the thin film magnetic head in the perpendicular recording method have already been proposed. Concretely, for example, there is a known structure including a write shield layer for receiving part of magnetic flux emitted from the magnetic pole layer on the trailing side of a magnetic pole layer in order to make the gradient of a perpendicular magnetic field sharp and increase the strength of the perpendicular magnetic field (refer to, for example, Japanese Patent Application No. 3368247).
For example, recently, another structure is also known which includes a write shield layer partly close to a magnetic pole layer via a thin gap layer on the side close to the air bearing surface in order to steepen the magnetic field gradient of a perpendicular magnetic field and increase the magnetic field strength in association with dramatic increase in areal density of a recording medium (for example, refer to “1 Tb/in2 Perpendicular Recording Conceptual Design”, M. Mallary, A. Torabi, and M. Benakli, 1st NAPMRC Technical Program, University of Miami, Jan. 7 to 9, 2002, and U. S. Pat. No. 465546).
To improve the recording performance of a thin film magnetic head of the perpendicular recording method and, more concretely, to enable a recording operation to be stably executed while keeping up with the areal density of a recording medium which is increasing, for example, it is necessary to steepen the gradient of the perpendicular magnetic field as much as possible and increase the strength of the magnetic field as much as possible. In the thin film magnetic head in the conventional perpendicular recording method, as described above, by providing the write shield layer, the gradient of the perpendicular magnetic field becomes sharper and the strength of the magnetic field increases. However, the magnetic field gradient and the magnetic field strength are not sufficient in viewpoint of stably executing the recording operation while addressing to rapid increase in the areal density, so that there is still room for improvement. Therefore, to improve the recording performance of the thin film magnetic head of the perpendicular recording method, it is desired to establish a technique capable of steepening the gradient of a perpendicular magnetic field and increasing the strength of the magnetic field as much as possible.
The present invention has been achieved in consideration of such problems and its object is to provide a thin film magnetic head and a magnetic recording apparatus realizing the gradient and strength of a perpendicular magnetic field increased as much as possible.
A thin film magnetic head according to a first aspect of the invention includes: a thin film coil that generates magnetic flux; a magnetic pole layer which extends from a side close to a recording-medium-facing surface facing a recording medium traveling in a medium travel direction toward a side far from the recording-medium-facing surface, and generates a magnetic field for magnetizing the recording medium in a direction orthogonal to the surface of the recording medium on the basis of the magnetic flux generated by the thin film coil; and a magnetic shield layer which extends from the side close to the recording-medium-facing surface toward the side far from the recording-medium-facing surface on the front side of the medium travel direction of the magnetic pole layer, is separated from the magnetic pole layer via a gap layer on the side close to the recording-medium-facing surface, and is coupled to the magnetic pole layer via a back gap on the side far from the recording-medium-facing surface, and the magnetic pole layer recedes from the magnetic shield layer to the side far from the recording-medium-facing surface.
A thin film magnetic head according to a second aspect of the invention includes: a magnetic pole layer that generates a recording magnetic field for magnetizing a recording medium in the perpendicular direction; and a magnetic shield layer disposed on the front side in a recording medium travel direction of the magnetic pole layer, and the magnetic pole layer recedes from the magnetic shield layer to the side apart from a recording-medium-facing surface.
In the thin film magnetic head according to the first or second aspect of the invention, since the magnetic pole layer recedes from the magnetic shield layer, the overlap range in which the magnetic pole layer and the magnetic shield layer overlap one another is smaller than that in the case where the magnetic pole layer does not recede from the magnetic shield layer. In this case, firstly, a front end portion of the magnetic pole layer is not easily magnetized in a direction largely deviated from the perpendicular direction (the direction from the magnetic pole layer toward a recording medium) due to the existence of the magnetic shield layer. Consequently, the front end portion is easily magnetized in the perpendicular direction also in a state where the magnetic shield layer exists. Second, the magnetic flux attraction acts between the magnetic pole layer and the magnetic shield layer, so that the front end portion of the magnetic pole layer tends to be strongly magnetized. Third, spread of the magnetic flux emitted from the magnetic pole layer is suppressed, so that the magnetic flux tends to be emitted in the perpendicular direction. Thus, the amount of the magnetic flux emitted from the magnetic pole layer toward a recording medium increases relatively, and the amount of the magnetic flux leaked from the magnetic pole layer to the magnetic shield layer decreases relatively.
The present invention also provides a magnetic recording apparatus on which a recording medium and a thin film magnetic head for performing a magnetic process on the recording medium are mounted. The thin film magnetic head comprises: a thin film coil that generates magnetic flux; a magnetic pole layer which extends from a side close to a recording-medium-facing surface facing a recording medium traveling in a medium travel direction toward a side far from the recording-medium-facing surface and generates a magnetic field for magnetizing the recording medium in a direction orthogonal to the surface of the recording medium on the basis of the magnetic flux generated by the thin film coil; and a magnetic shield layer which extends from the side close to the recording-medium-facing surface toward the side far from the recording-medium-facing surface on the front side in the medium travel direction of the magnetic pole layer, is separated from the magnetic pole layer via a gap layer on the side close to the recording-medium-facing surface, and is coupled to the magnetic pole layer via a back gap on the side far from the recording-medium-facing surface, and the magnetic pole layer recedes from the magnetic shield layer to the side far from the recording-medium-facing surface.
Since the thin film magnetic head is mounted on the magnetic recording apparatus according to the present invention, the amount of the magnetic flux emitted from the magnetic pole layer to the recording medium increases relatively, and the amount of the magnetic flux leaked from the magnetic pole layer to the magnetic shield layer decreases relatively.
In particular, in the thin film magnetic head according to the invention, preferably, a front end of the magnetic pole layer is positioned in a range where a portion separated from the magnetic pole layer via the gap layer in the magnetic shield layer extends. The “front end of the magnetic pole layer” denotes the edge closest to the recording-medium-facing surface of the magnetic pole layer. In this case, the magnetic shield layer is exposed in the recording-medium-facing surface, and the magnetic pole layer may not be exposed in the recording-medium-facing surface. Preferably, the magnetic pole layer has an end surface which is defined by a first edge positioned on the rear side in the medium travel direction and a second edge positioned on the front side in the medium travel direction in an end portion on the side close to the recording-medium-facing surface, and width of the second edge in the end surface is larger than that of the first edge and is equal to or larger than that of the end surface in an arbitrary intermediate position between the first and second edges.
In the thin film magnetic head and the magnetic recording apparatus according to the present invention, the overlap range in which the magnetic pole layer and the magnetic shield layer overlap one another is small on the basis of the structural feature that the magnetic pole layer recedes from the magnetic shield layer. Consequently, the amount of magnetic flux emitted from the magnetic pole layer toward a recording medium increases relatively, and the amount of magnetic flux leaked from the magnetic pole layer to the magnetic shield layer decreases relatively. Therefore, the gradient and the strength of a perpendicular magnetic field can be increased as much as possible.
An embodiment of the invention will be described in detail hereinbelow with reference to the drawings.
First, the configuration of a thin film magnetic head according to an embodiment of the invention will be described with reference to
In the following description, the dimension in the X-axis direction shown in
The thin film magnetic head according to the embodiment is to be mounted on a magnetic recording apparatus such as a hard disk drive in order to perform a magnetic process on a magnetic medium such as a hard disk traveling in the medium travel direction M. Concretely, the thin film magnetic head is, for example, a composite head capable of executing both a recording process and a reproducing process as magnetic processes. As shown in
The reproducing head portion 100A has a stacked layer structure in which, for example, a lower read shield layer 3, a shield gap film 4, and an upper read shield layer 5 are stacked in this order. An MR element 6 as a reproduction element is buried in the shield gap film 4 so that one end surface is exposed in a recording-medium-facing surface (air bearing surface 50) which faces a recording medium. The “air bearing surface 50” indicates a face specified on the basis of a front end face of a write shield layer 40 which will be described later, more concretely, a face including the front end face of the write shield layer 40.
The lower and upper read shield layers 3 and 5 are provided to magnetically isolate the MR element 6 from the periphery and extend rearward from the air bearing surface 50. The lower read shield layer 3 is made of, for example, a magnetic material such as nickel iron alloy (NiFe (for example, Ni: 80% by weight and Fe: 20% by weight) which will be simply called “permalloy (trademark)” hereinbelow). The upper read shield layer 5 has, for example, a stacking structure (three-layer structure) in which a nonmagnetic layer 5B is sandwiched between upper read shield layer portions 5A and 5C. Each of the upper read shield layer portions 5A and 5B is made of, for example, a magnetic material such as permalloy. The nonmagnetic layer 5B is made of, for example, a nonmagnetic material such as ruthenium (Ru) or alumina. The upper read shield layer 5 does not always have to have a stacking structure, but may have a single layer structure.
The shield gap film 4 is provided to electrically isolate the MR element 6 from the periphery and is made of, for example, a nonmagnetic insulating material such as alumina.
The MR element 6 executes a reproducing process by using giant magneto-resistive (GMR) effect, tunneling magneto-resistive (TMR) effect, or the like.
The recording head portion 100B has, for example, a stacked layer structure obtained by sequentially stacking a thin film coil 8 in a first stage buried by insulating layers 9, 10 and 11 in which an opening for magnetic coupling (a contact gap 10K) is provided and a coupling layer 12, a magnetic pole layer 30 whose periphery is buried by insulating layers 14 and 16, a gap layer 17 in which an opening for magnetic coupling (a back gap 17BG) is provided, a thin film coil 19 in a second stage buried by an insulating layer 20, and the write shield layer 40.
The thin film coil 8 mainly generates the magnetic flux for suppressing leakage in order to suppress leakage of a magnetic flux for recording generated by the thin film coil 19 and is made of, for example a high-conductive material such as copper (Cu). The thin film coil 8 has, for example, as shown in
The insulating layers 9 to 11 electrically isolate the thin film coil 8 from the periphery. The insulating layer 9 is provided so as to bury spaces between the turns of the thin film coil 8 and cover the periphery of the thin film coil 8. The insulating layer 9 is made of, for example, a nonmagnetic insulating material such as photoresist, spin on glass (SOG) or the like displaying flowability when heated. The insulating layer 9 is provided, for example as shown in
The magnetic pole layer 30 receives a magnetic flux for recording generated in the thin film coil 19, and executes a recording process by emitting the magnetic flux toward a recording medium. More concretely, the magnetic pole layer 30 generates a magnetic field (perpendicular magnetic field) for magnetizing a recording medium in the direction orthogonal to the surface of the recording medium on the basis of the magnetic flux for recording as a recording process in the perpendicular recording method. The magnetic pole layer 30 is positioned on the leading side of the thin film coil 19 and extends rearward from the air bearing surface 50, more concretely, to the position corresponding to the back gap 17BG. The “leading side” is an inflow side of a recording medium (the rear side in the medium travel direction M) when a traveling state of the recording medium traveling in the medium travel direction M shown in
In particular, the magnetic pole layer 30 has, for example, a stacking structure obtained by stacking sequentially an auxiliary magnetic pole layer 13 whose periphery is buried by the insulating layer 14 and the main magnetic pole layer 15 whose periphery is buried by the insulating layer 16. The magnetic pole layer 30 has, that is, a two-layer configuration in which the auxiliary magnetic layer 13 is disposed on the leading side and the main magnetic pole layer 15 is disposed on the trailing side.
The auxiliary magnetic pole layer 13 functions as a main magnetic flux receiving part and is adjacent to the main magnetic pole layer 15 so as to be magnetically coupled to each other. The auxiliary magnetic pole layer 13 extends, for example, rearward from a position receding from the air bearing surface 50, concretely, to a position corresponding to the back gap 17BG. The auxiliary magnetic pole layer 13 has, as shown in
The main magnetic pole layer 15 functions as a main magnetic flux emitting part and is adjacent to the auxiliary magnetic pole layer 13 so as to be magnetically coupled. The main magnetic pole layer 15 extends, for example as shown in
The main magnetic pole layer 15 has, for example as shown in
Particularly, the main magnetic pole layer 15 has, for example as shown in
The insulating layer 14 electrically isolates the auxiliary magnetic pole layer 13 from the periphery and is made of a nonmagnetic insulating material such as alumina. The insulating layer 16 electrically isolates the main magnetic pole layer 15 from the periphery and is made of a nonmagnetic insulating material such as alumina in a manner similar to the insulating layer 14.
The gap layer 17 is provided to form a gap for magnetic isolation between the magnetic pole layer 30 and the write shield layer 40 and, is made of, for example, a nonmagnetic insulating material such as alumina or a nonmagnetic conductive material such as ruthenium. The gap layer 17 has, for example, a thickness of tens nm, preferably, about 100 nm or less.
The thin film coil 19 generates the magnetic flux for recording. In the thin film coil 19, for example, a current flows in a direction opposite to that in the thin film coil 8. The other material, thickness, and structural features of the thin film coil 19 are, for example, similar to those of the thin film coil 8.
The insulating layer 20 electrically isolates the thin film coil 19 from the periphery by burying the thin film coil 19 and is disposed on the gap layer 17 so as not to close the back gap 17BG. The insulating layer 20 is made of, for example, a nonmagnetic insulating material such as photoresist or spin on glass displaying flowability when heated. The portions around the edges of the insulating layer 20 form round slopes inclined downward to the edges. The position of the front end (the edge closest to the air bearing surface 50) of the insulating layer 20 is the “throat height zero position TP” as one of important factors determining the recording performance of the thin film magnetic head. The distance between the throat height zero position TP and the air bearing surface 50 is a so-called “throat height TH”.
The write shield layer 40 is a magnetic shield layer to collect a part (spread component) of the magnetic flux emitted from the magnetic pole layer 30, thereby steepening the gradient of a magnetic field generated on the basis of the magnetic flux. The write shield layer 40 is positioned on the trailing side of the magnetic pole layer 30 and the thin film coil 19. The write shield layer 40 extends rearward from the air bearing surface 50, is isolated from the magnetic pole layer 30 by the gap layer 17 on the side close to the air bearing surface 50, and is magnetically coupled to the magnetic pole layer 30 via the back gap 17BG on the side far from the air bearing surface 50.
The write shield layer 40, for example, includes a TH specifying layer 18 and a yoke layer 21 constructed as members separate from each other and has a structure in which the TH specifying layer 18 and the yoke layer 21 are magnetically coupled to each other.
The TH specifying layer 18 functions as a main magnetic flux receiving port and has a length SH. The TH specifying layer 18 extends, for example as shown in
The yoke layer 21 functions as a passage of the magnetic flux received from the TH specifying layer 18. The yoke layer 21 extends, for example as shown in
In the thin film magnetic head, as described above, the write shield layer 40 is exposed in the air bearing surface 50 and, on the other hand, the main magnetic pole layer 15 is not exposed in the air bearing surface 50, that is, the main magnetic pole layer 15 is receded from the write shield layer 40. More concretely, the front end of the main magnetic pole layer 15, that is, the position of the end surface 15M is recede from the air bearing surface 50. The description “the write shield layer 40 is exposed in the air bearing surface 50” indicates that the write shield layer 40 constructs a part of the air bearing surface 50. On the other hand, the description “the main magnetic pole layer 15 is not exposed in the air bearing surface 50” indicates that the main magnetic pole layer 15 does not construct a part of the air bearing surface 50. On the basis of the indication, the mode “the write shield layer 40 is exposed in the air bearing surface 50 and the main magnetic pole layer 15 is not exposed in the air bearing surface 50” includes, as long as the main magnetic pole layer 15 is receded from the write shield layer 40, not only the mode in which the air bearing surface 50 is exposed as shown in
In particular, the front end of the main magnetic pole layer 15 (the edge closest to the air bearing surface 50) is positioned, for example, in a part separated from the magnetic pole layer 30 via the gap layer 17 in the write shield layer 40, that is, in a range where the TH specifying layer 18 in the write shield layer 40 extends. More concretely, the front end of the main magnetic pole layer 15 is positioned in a range of a length SH of the TH specifying layer 18.
In the thin film magnetic head, for example as shown
The operation of the thin film magnetic head will now be described with reference to
In the thin film magnetic head, at the time of recording information, when a current flows from a not-shown external circuit into the thin film coils 8 and 19 in the recording head portion 100B, a magnetic flux for recording is generated by the thin film coil 19. The generated magnetic flux is received by the magnetic pole layer 30 and, after that, flows toward the front end portion 15A in the main magnetic pole layer 15 inside of the main magnetic pole layer 30. Since the magnetic flux flowing in the main magnetic pole layer 15 is converged while being narrowed at the flare point FP as the width of the main magnetic pole layer 15 decreases, the magnetic flux is finally concentrated on the neighborhood of the trailing edge TE in the end surface 15M of the front end portion 15A. When the magnetic flux concentrated on the neighborhood of the trailing edge TE is emitted to the outside via the air bearing surface 50 to thereby generate a recording magnetic field (perpendicular magnetic field) in the direction (perpendicular direction) orthogonal to the surface of a recording medium, the recording medium is magnetized by the perpendicular magnetic field so that information is magnetically recorded onto the recording medium.
In particular, at the time of recording information, currents flow into the thin film coils 8 and 19 so as to be in directions opposite to each other, so that the magnetic fluxes are generated in directions opposite to each other in the thin film coils 8 and 19, respectively. Concretely, with reference to
At the time of recording information, a part of the magnetic flux for recording emitted from the magnetic pole layer 30 (a spread component) is received by the write shield layer 40, so that the spread of the magnetic flux is suppressed. Consequently, the gradient of the perpendicular magnetic field becomes sharp. The magnetic flux received by the write shield layer 40 is circulated into the magnetic pole layer 30 via the back gap 17BG.
On the other hand, at the time of reproducing information, when a sense current flows into the MR element 6 of the reproducing head portion 100A, the resistance value of the MR element 6 changes according to a signal magnetic field for reproduction based on the recording medium. Therefore, by detecting the resistance change of the MR element 6 as a change in the sense current, information recorded on the recording medium is magnetically reproduced.
In the thin film magnetic head of the embodiment, the main magnetic pole layer 15 is provided so as to be receded from the write shield layer 40. Therefore, for the following reason, the gradient and the strength of the perpendicular magnetic field can be increased as much as possible.
In the thin film magnetic head of the comparative example, as shown in
In the thin film magnetic head of the comparative example, an overlap range LA in which the main magnetic pole layer 115 and the write shield layer 40 overlap one another is excessive large due to the structure in which the main magnetic pole layer 115 is exposed in the air bearing surface 50 in a similar manner to the write shield layer 40. In this case, due to the phenomenon that the overlap range LA becomes excessive large in a state where the write shield layer 40 is close to the trailing side of the main magnetic pole layer 115 via the thin gap layer 17, a front end portion of the main magnetic pole layer 115 is easily magnetized in a direction largely deviated from the perpendicular direction (largely deviated to the trailing side) due to the existence of the write shield layer 40. Consequently, the front end portion in the main magnetic pole layer 115 is not easily magnetized in the perpendicular direction in a state where the write shield layer 40 exists. Accordingly, the amount of the emitted magnetic fluxes J1 emitted from the main magnetic pole layer 115 toward the recording medium 60 relatively decreases and the leakage magnetic fluxes J2 leaked from the main magnetic pole layer 115 toward the write shield layer 40 relatively increases. Therefore, in the thin film magnetic head of the comparative example, it is difficult to increase the gradient and the strength of the perpendicular magnetic field as much as possible.
On the other hand, in the thin film magnetic head of the embodiment, as shown in
In the thin film magnetic head of the embodiment, in comparison with the thin film magnetic head of the comparative example in which the main magnetic pole layer 115 is exposed in the air bearing surface 50 in a similar manner to the write shield layer 40 (refer to
Particularly, in the embodiment, the front end of the main magnetic pole layer 15 is positioned in a range where a portion separated from the magnetic pole layer 30 via the gap layer 17 in the write shield layer 40 extends. Consequently, as shown in
In the embodiment, the end surface 15M of the main magnetic pole layer 15 emitting the magnetic flux to generate the perpendicular magnetic field has an inverted trapezoidal shape which is bilaterally symmetrical in plan view. Consequently, even if a skew occurs in a recording operation of the thin film magnetic head, that is, the main magnetic pole layer 15 is inclined from the tangential direction of a track to be recorded (a specific track on which information is to be recorded) which is provided in a curved line shape in the recording medium, the end surface 15M in the main magnetic pole layer 15 does not go off the track to be recorded to an adjacent track (another track adjacent to the track to be recorded). In the case, different from the case where the end surface 15M goes off the track to be recorded into the adjacent track when the skew occurs due to the structural factor that the end surface 15M has a rectangular shape in plan view, magnetization of not only the track to be recorded but also the adjacent track by the perpendicular magnetic field is suppressed. Consequently, unintentional erasure of information recorded on the recording medium due to a skew can be suppressed in information recording.
In the embodiment, the thin film coil 19 which generates the magnetic flux for recording is provided on the trailing side of the main magnetic pole layer 15, and the thin film coil 8 which generates the magnetic flux for suppressing leakage is also provided on the leading side of the main magnetic pole layer 15 in order to suppress leakage of the magnetic flux for recording generated by the thin film coil 19. Consequently, as described above, if the magnetic fluxes are generated in directions opposite to each other in the thin film coils 8 and 19 by passing currents to the thin film coils 8 and 19 in directions opposite to each other at the time of recording information, by the influence of the upward magnetic flux (magnetic flux for suppressing leakage) generated by the thin film coil 8, leakage of the downward magnetic flux (magnetic flux for recording) generated by the thin film coil 19 from the recording head portion 100B to the production head portion 100A is suppressed. Therefore, the magnetic flux for recording generated by the thin film coil 19 is efficiently emitted from the air bearing surface 50 via the main magnetic pole layer 15, so that the gradient and the strength of the perpendicular magnetic field can be increased also from this viewpoint.
The significance from the technical viewpoint of the thin film magnetic head according to the invention will now be described. Specifically, the structural characteristic of the thin film magnetic head of the invention is that the main magnetic pole layer 15 is receded from the write shield layer 40. The layout relation between the main magnetic pole layer 15 and the write shield layer 40 is a layout relation when the thin film magnetic head is not operated, that is, in a state where the thin film coils 8 and 19 are not energized, not a disposition relation when the thin film magnetic head is operated, that is, in a state the thin film coils 8 and 19 are energized. More concretely, an example of known modes in which the main magnetic pole layer 15 is receded from the write shield layer 40 is as follows. When a thin film magnetic head is constructed so that both of the main magnetic pole layer 15 and the write shield layer 40 are exposed in the air bearing surface 50, the main magnetic layer 15 and the write shield layer 40 are expanded due to the heat generated by passage of current to the thin film coils 8 and 19. As a result, the main magnetic pole layer 15 is unintentionally receded from the write shield layer 40. The phenomenon is generally known as a deficiency called “protrusion deficiency (so-called protrusion)” which occurs during the operation of the thin film magnetic head. However, the layout relation between the main magnetic pole layer 15 and the write shield layer 40 specified in the present invention is different from that at the time of occurrence of the protrusion deficiency but is a structural design specification of the thin film magnetic head. The layout relation of the present invention is directed to increase the gradient and the strength of the perpendicular magnetic field as much as possible. By making the main magnetic pole layer 15 intentionally receded from the write shield layer 40, the write shield layer 40 is exposed in the air bearing surface 50 while the main magnetic pole layer 15 is not exposed in the air bearing surface 50. Therefore, the thin film magnetic head according to the present invention has the technical significance from the viewpoint of increasing the gradient and the strength of the perpendicular magnetic field as much as possible by the design that the main magnetic pole layer 15 is receded from the write shield layer 40 at the time of non-operation. For information, in the case where the protrusion deficiency occurs in the thin film magnetic head, generally, heat tends to be accumulated in the main magnetic pole layer 15 more than the write shield layer 40. In other words, the main magnetic pole layer 15 tends to protrude more than the write shield layer 40. Considering the tendency, it is more obviously understood that the structural characteristic of the thin film magnetic head according to the invention is different from the structure eventually obtained due to the protrusion deficiency.
In the embodiment, as shown in
In the embodiment, as shown in
When the components of the thin film magnetic head are partly receded from the air bearing surface 50 as shown in
The thin film magnetic head according to the embodiment have been described above.
Next, with reference to
The magnetic recording apparatus has, as shown in
The magnetic head slider 202 has a configuration such that, as shown in
In the magnetic recording apparatus, at the time of recording or reproducing information, by swing of the arm 204, the magnetic head slider 202 moves to a predetermined region (recording region) in the magnetic disk 201. When current is passed to the thin film magnetic head 212 in a state where the thin film magnetic head 212 faces the magnetic disk 201, the thin film magnetic head 212 operates on the basis of the operation principle described in the foregoing embodiment and performs a recording or reproducing process on the magnetic disk 201.
In the magnetic recording apparatus, the thin film magnetic head 212 of the embodiment is mounted. Consequently, as described above, the gradient and the strength of the perpendicular magnetic field can be increased as much as possible.
The other configuration, operation, action, effects, and modification of the thin film magnetic head 212 mounted on the magnetic recording apparatus are similar to those of the foregoing embodiment, so that their description will not be repeated.
Next, examples of the present invention will be described.
The thin film magnetic head (refer to
At the time of examining the gradient and the strength of the perpendicular magnetic field, as constructional conditions of the thin film magnetic head (refer to
First, the correlation between the maximum gradient of the perpendicular magnetic field and the recess height was examined and results shown in
As understood from the results shown in
Subsequently, the correlation between the magnetic field gradient and the recess height in the case where the strength of the perpendicular magnetic field is set to a specific value was examined, and results shown in
As understood from the results shown in
Subsequently, the correlation between the gradient of the perpendicular magnetic field and the recess height was examined, and results shown in
As understood from the results shown in
The foregoing embodiment does not mention the influence exerted on the gradient and the strength of the perpendicular magnetic field in the case of changing each of, for example, the thickness of the gap layer 17, the thickness of the main magnetic pole layer 15, and the thickness of the TH specifying layer 18 in the write shield layer 40 at the time of examining the gradient and the strength of the perpendicular magnetic field. However, by making the main magnetic pole layer 15 recede from the write shield layer 40, also in the case where the thicknesses of the series of components fluctuate, although some variations may occur, the tendency that the gradient and the strength of the perpendicular magnetic field increase can certainly be obtained. For reference purposes, hereinbelow, results of the examination of the gradient and the strength of the perpendicular magnetic field in the case where each of the thickness of the gap layer 17 and the thickness of the main magnetic pole layer 15 is changed as representatives of the series of components will be described.
At the time of examining the gradient and the strength of the perpendicular magnetic field when each of the thickness of the gap layer 17 and the thickness of the main magnetic pole layer 15 is changed, as constructional conditions of the thin film magnetic head (refer to
First, the behaviors of the strength and the maximum gradient of the perpendicular magnetic field in the case where the thickness of the gap layer 17 is changed were examined and results shown in Tables 1 and 2 were obtained. Table 1 shows the behavior of the magnetic field strength. Table 2 shows the behavior of the maximum magnetic field gradient. In Tables 1 and 2, “comparative example” corresponds to the thin film magnetic head of the comparative example shown in
As understood from the results shown in Table 1, when the thickness of the gap layer 17 was changed in three levels of 10 nm, 50 nm, and 100 nm, the magnetic field strength increased in the present invention (RH=−5 nm) more than that in the comparative example (RH=0 nm) at any of the set values of the thickness of the gap layer 17. Further, as understood from the results shown in Table 2, when the thickness of the gap layer 17 was similarly changed in three levels of 10 nm, 50 nm and 100 nm the maximum magnetic field gradient similarly increased in the present invention (RH=−5 nm) more than that in the comparative example (RH=0 nm) at any of the set values of the thickness of the gap layer 17. It was consequently confirmed that in the thin film magnetic head of the invention, by making the main magnetic pole layer 15 recede from the write shield layer 40, the strength of the perpendicular magnetic field is increased irrespective of the thickness of the gap layer 17.
Subsequently, the behaviors of the strength and the maximum gradient of the perpendicular magnetic field in the case of changing the thickness of the main magnetic pole layer 15 were examined, and results shown in
As understood from the results shown in
Although the invention has been described above by the embodiment and the examples, the invention is not limited to the foregoing embodiment and examples but can be variously modified. Concretely, for example, although the case of applying the thin film magnetic head of the invention to a composite thin film magnetic head has been described in the foregoing embodiment and the examples, the invention is not limited to the case. The invention can be also applied to, for example, a recording-only thin film magnetic head having an inductive magnetic transducer for writing and a thin film magnetic head having an inductive magnetic transducer for recording and reproduction. Obviously, the invention can be also applied to a thin film magnetic head having a structure in which a device for writing and a device for reading are stacked in the order opposite to that of the thin film magnetic head of the embodiment. In any of those cases, effects similar to those of the foregoing embodiment can be obtained.
The thin film magnetic head according to the invention can be applied to, for example, a magnetic recording apparatus such as a hard disk drive for magnetically recording information onto a hard disk.
Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.
Number | Date | Country | Kind |
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2005-028875 | Apr 2005 | JP | national |