# Patent

## Title
Method and system for providing an antiferromagnetically coupled return pole

## Abstract

A method and system provide a magnetic head having an air-bearing surface (ABS). The magnetic head includes a read transducer and a write transducer. The read transducer includes a first shield and a read sensor. The write transducer includes a main pole, at least one coil for energizing the main pole and a return pole between the read sensor and the main pole. The return pole includes an antiparallel coupling (AC) pole structure. The AC pole structure includes a plurality of ferromagnetic layers interleaved with at least one nonmagnetic layer. The ferromagnetic layers and the nonmagnetic spacer layer(s) are substantially parallel. The ferromagnetic layers and the nonmagnetic spacer layer(s) are substantially perpendicular to the ABS. The magnetic moment of each of the ferromagnetic layers is aligned antiparallel with the magnetic moment of a nearest neighbor of the ferromagnetic layers.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to provisional U.S. Patent Application Ser. No. 61/807,542, filed on Apr. 2, 2013, which is hereby incorporated by reference in its entirety.


BACKGROUND
FIG. 1 depicts a side view of a conventional magnetic recording head. The conventional magnetic recording head 10 includes a read transducer 12 and a write transducer 20. The conventional read transducer 12 includes shields 14 and 18 and sensor 16. The read sensor 16 is typically a giant magnetoresistive (GMR) sensor or tunneling magnetoresistive (TMR) sensor. The write transducer 20 includes a first, or return, pole 22, coils 24 and 32, back gap 26, auxiliary pole 28, main pole 30 and shield 344. The back gap 26 may be used to connect the return pole 22 with the auxiliary pole 28 and, therefore, the main pole 30. In addition, although not shown, the shield 18 may be an antiferromagnetically coupled shield. For example, the shield 18 may include ferromagnetic layers separated by a nonmagnetic spacer layer configured such that the magnetic moments of the ferromagnetic layers are antiferromagnetically coupled. In addition, an antiferromagnetic (AFM) layer may also be provided in the shield 18.
Although the conventional magnetic recording head 10 functions, there are drawbacks. In particular, the first pole 22 may be unstable. For example, the first pole 22 may be magnetically dynamic. In other words, the first pole 22 may be magnetically active even if there is no current driven through the coils 24 and 32. Further, magnetic coupling between the first pole 22 and the shield 18 may be a source of reader instability. Accordingly, what is needed is a system and method for improving the performance of a magnetic recording head.



BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 depicts a conventional magnetic recording head.
FIG. 2 depicts an exemplary embodiment of a magnetic recording head.
FIG. 3 depicts a side view of another exemplary embodiment of a magnetic recording head.
FIG. 4 depicts an ABS view of another exemplary embodiment of a magnetic recording head.
FIG. 5 depicts another exemplary embodiment of a magnetic recording head.
FIG. 6 depicts another exemplary embodiment of a magnetic recording head.
FIG. 7 depicts another exemplary embodiment of a magnetic recording head.
FIG. 8 is flow chart depicting an exemplary embodiment of a method for fabricating a magnetic recording head.
FIG. 9 is flow chart depicting an exemplary embodiment of a method for fabricating a portion of an antiparallel coupled pole.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 2 depicts an ABS view of a portion of an exemplary embodiment of a magnetic recording head 100. For clarity, FIG. 2 is not to scale. The magnetic recording head 100 includes a read transducer 110 and a writer transducer 120. For simplicity, only a portion of the write transducer 120 is shown. The transducer 110 includes shields 112 and 116 as well as a read sensor 114. The sensor 114 shown is a GMR or TMR sensor. Thus, the sensor 114 may include a pinning layer, a pinned, a nonmagnetic spacer layer, a free layer, and a capping layer. For simplicity, these layers are not separately labeled in FIG. 2. The sensor 14 may also include seed layer(s) (not shown). Although an AFM layer used to pin the magnetic moment of the pinned layer is shown, in other embodiments, the pinning layer may be omitted or may use a different pinning mechanism. The pinned layer and free layer are each shown as a single layer, but may include multiple layers including but not limited to a synthetic antiferromagnetic (SAF) structure. The nonmagnetic spacer layer may be a conductive layer, a tunneling barrier layer, or other analogous layer. Although depicted as a GMR or TMR sensor, in other embodiments, other structures and other sensing mechanisms may be used for the sensor.
The read transducer 110 may also include magnetic bias structures, which are not shown in FIG. 2. In some embodiments, these magnetic bias structures may be soft bias structures fabricated with soft magnetic material(s). In other embodiments, other magnetic bias structures including but not limited to hard magnetic bias structures might be used.
The shield 116 for the magnetic read transducer 110 may be an antiferromagnetically coupled (AFC) shield. The shield 110 may include ferromagnetic layers interleaved with nonmagnetic spacer layer(s). In addition, a pinning layer, such as an antiferromagnetic layer, may also be included. The nonmagnetic spacer layer may be Ru, which allows the magnetic moments of the ferromagnetic layers to be coupled antiparallel, for example through an RKKY coupling. In some embodiments, the ferromagnetic layers are multilayers. For example a ferromagnetic layer may be a bilayer including a NiFe layer and CoxFe1-x layer.
In some embodiments, a piggyback layer 118 is included between the read transducer 110 and the write transducer 120. The piggyback layer 118 is typically a nonmagnetic layer. In some embodiments, the piggyback layer 118 may three thousand five hundred Angstroms or more thick. Without more, therefore, stray fields might penetrate further into the shield 116. However, the configuration of other portions of the magnetic recording head 100 may mitigate this issue. However, in other embodiments, the piggyback layer 118 may be omitted. In such embodiments, the return pole 130 may adjoin the shield 116.
The write transducer 120 includes a main pole (not shown in FIG. 2) as well as one or more coils (not shown in FIG. 2) for energizing the main pole. In addition, the write transducer 120 includes a return pole 130. In some embodiments, the return pole 130 may be coupled to the main pole through a back gap (not shown). The return pole 130 includes an antiparallel coupling (AC) structure 140 as well as optional additional magnetic layers 132 and 134. In some embodiments, the additional magnetic layers 132 and/or 134 may be omitted. The AC structure 140 includes at least two ferromagnetic layers interleaved with and sandwiching at least one nonmagnetic layer. For simplicity, these layers are not shown in FIG. 2. For example, the AC structure 140 may include two ferromagnetic layers separated by a nonmagnetic layer. In other embodiments, the AC structure 140 may include three ferromagnetic layers separated by two nonmagnetic layers or four ferromagnetic layers separated by three nonmagnetic layers. Other numbers of ferromagnetic layers and nonmagnetic layers may be used in other embodiments. As can be seen in FIG. 2, the AC structure 140 is perpendicular to the ABS. Stated differently, the plane of the AC structure, in which the lateral dimensions are large compared with the down track direction, is perpendicular to the ABS. Thus, the ferromagnetic and nonmagnetic layers in the AC structure 140 are also perpendicular to the ABS. In addition, as can be seen in FIG. 2 the AC structure 140 and thus the layers therein, are also perpendicular to the down track direction. Stated differently, the plane of the AC structure 140 and the layers therein are perpendicular to the down track direction.
The AC structure 140 is so termed because the magnetic moments of the ferromagnetic layers of the AC structure are coupled antiparallel. In some embodiments, the magnetic moments are perpendicular to the ABS. In other embodiments, the magnetic moments are perpendicular to the down track direction, in the cross track direction. For both such embodiments, the magnetic moments may be in-plane for the AC structure. In other embodiments, the magnetic moments may be in another direction. In some embodiments, the magnetic moments are antiferromagnetically coupled. For example, the magnetic moments may be coupled through an RKKY coupling that results in the magnetic moments of the ferromagnetic layers being antiferromagnetically aligned. In such embodiments, the AC structure 140 is an antiferromagnetically coupled (AFC) structure. In some embodiments, the thickness of the nonmagnetic layer(s) is configured such that the AFC coupling is at the first, second or third antiferromagnetically coupled peak of the RKKY interaction.
In some embodiments, the AC structure 140 does not extend from the ABS to the back of the pole 130, as is shown in FIG. 2. However, in other embodiments, the AFC structure may not terminate between the ABS and the back of the pole 130. In such embodiments, the AC structure 140 extends from the ABS to the back of the pole 130. In some embodiments, at least the AFC structure 140 is fabricated by sputtering. For example, the ferromagnetic layers and nonmagnetic layer(s) may be formed by alternately sputtering the desired magnetic materials, such as CoFe, and nonmagnetic material(s), such as Ru. The remaining magnetic layers 132 and 134 of the pole 130 may be plated.
The magnetic head 100 may have improved performance. The AC structure 140 may improve the stability of the return pole 130. For example, the AC structure 140 may reduce the changes in domains of the pole 130. Thus, the return pole 130 may be less magnetically active. It may be possible for the pole 130 to reach a single domain state. In such a case, the formation of domain walls in the pole 130 may be reduced and remanent dynamics of the pole 130 improved. Further, the magnetostatic coupling between the pole 130 and the shield 116 may be reduced. Consequently, stability of the read sensor 114 may be improved. Thus, performance of the writer 120 and reader 110 may be enhanced.
FIGS. 3 and 4 depict side and ABS views of an exemplary embodiment of a magnetic head 100′. Note that the ABS view depicted in FIG. 4 is of the return pole 130 only. For clarity, FIGS. 3 and 4 are not to scale. The magnetic recording head 100′ is analogous to the magnetic head 100. Consequently, analogous components have similar labels. The magnetic recording head 100′ thus includes a read transducer 110′ and a writer transducer 120′. The read transducer 110′ includes shields 112 and 116′ as well as a read sensor 114. The sensor 114 may be a GMR or TMR sensor. In other embodiments, other structures and other sensing mechanisms may be used for the sensor. The read transducer 110′ may also include magnetic bias structures (not shown).
The shield 116′ for the magnetic read transducer 110′ is an antiferromagnetically coupled (AFC) shield. The shield 110′ thus includes ferromagnetic layers 115 and 119 interleaved with a nonmagnetic spacer layer 117. In addition, a pinning layer, such as an antiferromagnetic layer, may also be included. The nonmagnetic spacer layer 117 may be Ru, which allows the magnetic moments of the ferromagnetic layers 115 and 119 to be antiferromagnetically coupled, for example through an RKKY coupling. In some embodiments, the ferromagnetic layers 115 and 119 may be multilayers. For example a ferromagnetic layer 115 and/or 119 may be a bilayer including a NiFe layer and CoxFe1-x layer.
In some embodiments, the nonmagnetic piggyback layer 118 is included between the read transducer 110′ and the write transducer 120′. For example, the piggyback layer 118 may be formed of alumina. In some embodiments, the piggyback layer 118 may be three thousand five hundred Angstroms or more thick. However, in other embodiments, the piggyback layer 118 may be omitted. In such embodiments, the return pole 130′ may adjoin the shield 116′.
The write transducer 120′ includes a return pole 130′, coils 152 and 158, back gap 150 and a main pole 156. Shield 160 may also be included. In the embodiment shown, the coils 152 and 158 may be parts separate pancake coils or may form a single helical coil. A single auxiliary pole 154 is denoted in FIG. 3. In other embodiments, the auxiliary pole 154 may be on the opposite side of the main pole 156 in the down track direction. In still other embodiments, two auxiliary poles that sandwich the main pole 156 may be used. Such an embodiment is depicted in FIG. 3. In the embodiment shown, the back gap 150 connects the main pole 156 with the return pole 130′ through the auxiliary pole 154. In other embodiments, the back gap 150 may be omitted. In addition, in the embodiment shown, the return pole 130′ extends further from the ABS than the back gap 150. In other embodiments, however, other configurations may be used.
Also shown in FIGS. 3-4 is the return pole 130′. The return pole 130′ includes an AC structure 140′ as well as optional additional magnetic layers 132 and 134. In some embodiments, the additional magnetic layers 132 and/or 134 may be omitted. The AC structure 140′ includes two ferromagnetic layers 142 and 146 interleaved with and sandwiching a nonmagnetic layer 144. Other numbers of ferromagnetic layers and nonmagnetic layers may be used in other embodiments. As can be seen in FIG. 3, the magnetic moment of the layer 142 is antiparallel to the magnetic moment of the ferromagnetic layer 146. In some embodiments, the magnetic moments are antiferromagnetically coupled. Thus, the AC structure 140′ may be an AFC structure 140′. For example, the magnetic moments of the layers 142 and 146 may be coupled through the nonmagnetic layer 144 via an RKKY coupling. In some embodiments, the thickness of the nonmagnetic layer 144 is configured such that the AFC coupling is at the first, second or third antiferromagnetically coupled peak of the RKKY coupling. In such embodiments, the nonmagnetic layer 144 may be a Ru layer. For the first or second peak in the RKKY coupling, the nonmagnetic layer 144 may be not more than ten Angstroms thick. For the third peak, the nonmagnetic layer 144 may be thicker, for example on the order of twenty-two through twenty-eight Angstroms. In some embodiments, the nonmagnetic layer 144 is desired to be thinner such that the first or second peak of the RKKY coupling characterizes the antiferromagnetic coupling between the layers 142 and 146. Thus, the layers 142 and 146 would be more strongly antiferromagnetically coupled. In some embodiments, the magnetic layers 142 and 146 are desired to have a thickness of at least fifty-five nanometers and not more than eighty-five nanometers. In addition, the magnetic layers 142 and 146 may be desired to be formed of CoFe.
In the embodiment shown, the magnetic moments of the ferromagnetic layers 142 and 146 are not only antiparallel, but also perpendicular to the ABS. In other embodiments, the magnetic moments may be in other directions. However, the magnetic moments are still desired to be antiparallel.
In some embodiments, the AC structure 140′ extends from the ABS to the back of the pole 130′, as is shown in FIG. 3. However, in other embodiments, the AFC structure may terminate between the ABS and the back of the pole 130′. In some embodiments, at least the AFC structure 140′ is fabricated by sputtering. For example, the ferromagnetic layer 142 may be sputter deposited, the nonmagnetic layer 144 may then be sputtered, and the ferromagnetic layer 146 sputtered last. The remaining magnetic layers 132′ and 134′ of the pole 130′ may be plated.
As can be seen in FIGS. 3-4, the layers 142, 144 and 146 of the AC structure 140′ are substantially parallel to each other. In addition, the layers 142, 144 and 146 are substantially perpendicular to the ABS. Stated differently, the planes of the layers 142, 144 and 146 extend in the cross track and stripe height direction, with the smallest dimension being in the down track direction. In the embodiment shown, the magnetic moments of ferromagnetic layers 142 and 146 are also perpendicular to the ABS, in the stripe height direction.
The layers 132′ and 134′ are also ferromagnetic. In some embodiments, the layers 132′ and 134′ are formed of NiFe. The magnetic moments of the layers 132′ and 134′ are ferromagnetically coupled with the magnetic moments of the layers 142 and 146, respectively. Thus, the layers 142 and 132′ have their magnetic moments antiparallel to the magnetic moments of the layers 146 and 134′.
The magnetic head 100′ may have improved performance. The AC structure 140′ may improve the stability of the return pole 130′. For example, the AC structure 140′ may allow the return pole 130′ to be less magnetically active. It may be possible for the pole 130′ to reach a single domain state. In such a case, the formation of domain walls in the pole 130′ may be reduced and remanent dynamics of the pole 130′ improved. Further, the magnetostatic coupling between the pole 130′ and the shield 116′ may be reduced. Consequently, stability of the read sensor 114 may be improved. Thus, performance of the writer 120′ and reader 110′ may be enhanced.
FIG. 5 depicts a side view of an exemplary embodiment of a magnetic head 100′′. For clarity, FIG. 5 is not to scale. The magnetic recording head 100′′ is analogous to the magnetic head 100 and 100′. Consequently, analogous components have similar labels. The magnetic recording head 100′′ thus includes a read transducer 110′′ and a writer transducer 120′′. The read transducer 110′′ includes shield 112, AFC shield 116′ as well as a read sensor 114. The sensor 114 may be a GMR or TMR sensor. In other embodiments, other structures and other sensing mechanisms may be used for the sensor. The read transducer 110′′ may also include magnetic bias structures (not shown).
The shield 116′ for the magnetic read transducer 110′′ is an AFC shield analogous to the AFC shield 116′ shown in FIG. 3. In some embodiments, the nonmagnetic piggyback layer 118 is included between the read transducer 110′′ and the write transducer 120′′. The piggyback layer 118 is analogous to the piggyback layer 118 depicted in FIG. 3. However, in other embodiments, the piggyback layer 118 may be omitted. In such embodiments, the return pole 130′ may adjoin the shield 116′.
The write transducer 120′ includes a return pole 130′, coils 152 and 158, auxiliary pole(s) 154, and a main pole 156. Shield 160 may also be included. The components 130′, 152, 156, 158, 154 and 160 in FIG. 5 are analogous to components 130′, 152, 156, 158, 154 and 160 in FIG. 3. The return pole 130′ thus includes an AC structure 140′ as well as optional additional magnetic layers 132′ and 134′. In some embodiments, the additional magnetic layers 132′ and/or 134′ may be omitted. The layers 132′ and 134′ are ferromagnetic and may be formed of NiFe. The magnetic moments of the layers 132′ and 134′ are ferromagnetically coupled with the magnetic moments of the layers 142 and 146, respectively.
The AC structure 140′ includes two ferromagnetic layers 142 and 146 interleaved with and sandwiching a nonmagnetic layer 144. Other numbers of ferromagnetic layers and nonmagnetic layers may be used in other embodiments. As can be seen in FIG. 5, the magnetic moment of the layer 142 is antiparallel to the magnetic moment of the ferromagnetic layer 146. In some embodiments, the magnetic moments are antiferromagnetically coupled. Thus, the AC structure 140′ may be an AFC structure 140′. For example, the magnetic moments of the layers 142 and 146 may be coupled through the nonmagnetic layer 144 via an RKKY coupling. The thicknesses and constituents of the layers 142, 144 and 146 may be analogous to those shown in FIG. 3. In the embodiment shown, the magnetic moments of the ferromagnetic layers 142 and 146 are not only antiparallel, but also perpendicular to the ABS. In other embodiments, the magnetic moments may be in other directions. However, the magnetic moments are still desired to be antiparallel. The layers 142, 144 and 146 of the AC structure 140′ are substantially parallel to each other. In addition, the layers 142, 144 and 146 are substantially perpendicular to the ABS.
In some embodiments, the AC structure 140′ extends from the ABS to the back of the pole 130′, as is shown in FIG. 5. However, in other embodiments, the AFC structure may terminate between the ABS and the back of the pole 130′. In some embodiments, at least the AFC structure 140′ is fabricated by sputtering. For example, the ferromagnetic layer 142 may be sputter deposited, the nonmagnetic layer 144 may then be sputtered, and the ferromagnetic layer 146 sputtered last. The remaining magnetic layers 132′ and 134′ of the pole 130′ may be plated. In the embodiment shown, the magnetic moments of ferromagnetic layers 142 and 146 are also perpendicular to the ABS, in the stripe height direction.
In the embodiment shown, the return pole 130′ is not coupled to the main pole 156 through a back gap. Thus, the back gap 150 in the embodiment depicted in FIG. 3 is not present in the embodiment shown in FIG. 5.
The magnetic head 100′′ may have improved performance. The AC structure 140′ may improve the stability of the return pole 130′. For example, the AC structure 140′ may allow the return pole 130′ to be less magnetically active. The suppression of the dynamic nature of the return pole 130′ may be enhanced by the omission of the back gap. In some embodiments, the formation of domain walls in the pole 130′ may be reduced and remanent dynamics of the pole 130′ improved. Further, the magnetostatic coupling between the pole 130′ and the shield 116′ may be reduced. Consequently, stability of the read sensor 114 may be improved. Thus, performance of the writer 120′′ and reader 110′′ may be enhanced.
FIG. 6 depicts a side view of an exemplary embodiment of a magnetic head 100′′′. For clarity, FIG. 6 is not to scale. The magnetic recording head 100′′′ is analogous to the magnetic heads 100, 100′ and 100′′. Consequently, analogous components have similar labels. The magnetic recording head 100′′′ thus includes a read transducer 110′′′ and a writer transducer 120′′′. The read transducer 110′′′ includes shield 112, AFC shield 116′ as well as a read sensor 114. The sensor 114 may be a GMR or TMR sensor. In other embodiments, other structures and other sensing mechanisms may be used for the sensor. The read transducer 110′′′ may also include magnetic bias structures (not shown).
The shield 116′ for the magnetic read transducer 110′′′ is an AFC shield analogous to the AFC shields previously shown. In the embodiment shown, the write transducer 120′′′ and thus the return pole 130′′ adjoins the AFC shield 116′. Thus, the nonmagnetic piggyback layer depicted in previous embodiments is not shown in FIG. 6. However, in other embodiments, the piggyback layer 118 may be included.
The write transducer 120′′′ includes a return pole 130′′, coils 152 and 158, auxiliary pole(s) 154, back gap 150 and a main pole 156. Shield 160 may also be included. The components 130′′, 150, 152, 154, 156, 158 and 160 in FIG. 6 are analogous to components 130/130′, 150, 152, 154, 156, 158 and 160 depicted in previous drawings. In the embodiment shown, the return pole 130′′ is coupled to the main pole 156 through a back gap 150. In other embodiments, the back gap 150 may be omitted.
The return pole 130′′ thus includes an AC structure 140′′ as well as optional additional magnetic layers 132′′ and 134′′. In some embodiments, the additional magnetic layers 132′′ and/or 134′′ may be omitted. The layers 132′′ and 134′′ are ferromagnetic and may be formed of NiFe. The magnetic moments of the layers 132′′ and 134′′ are ferromagnetically coupled with the magnetic moments of the layers 148 and 146, respectively.
The AC structure 140′′ includes three ferromagnetic layers 142, 146 and 148 interleaved with and sandwiching two nonmagnetic layers 144 and 147. Other numbers of ferromagnetic layers and nonmagnetic layers may be used in other embodiments. As can be seen in FIG. 6, the magnetic moment of a ferromagnetic layer 142, 146 and 148 is antiparallel to the magnetic moment of the nearest neighbor ferromagnetic layer. For example, the magnetic moment of the layer 148 is antiparallel to the magnetic moment of the layer 142. The magnetic moment of the layer 146 is also antiparallel to the magnetic moment of the layer 142. In some embodiments, the magnetic moments are antiferromagnetically coupled. Thus, the AC structure 140′′ may be an AFC structure 140′′. For example, the magnetic moments of the ferromagnetic layers 142 and 146 and the ferromagnetic layers 146 and 148 may be coupled through the nonmagnetic layers 142 and 147, respectively. This coupling may be an RKKY coupling. The thicknesses and constituents of the layers 142, 144, 146, 147 and 148 may be analogous to those shown in previous drawings. In the embodiment shown, the magnetic moments of the ferromagnetic layers 142 and 146 and the magnetic moments of the layers 142 and 148 are not only antiparallel, but also perpendicular to the ABS. In other embodiments, the magnetic moments may be in other directions. However, the magnetic moments are still desired to be antiparallel. The layers 142, 144, 146, 147 and 148 of the AC structure 140′′ are substantially parallel to each other. In addition, the layers 142, 144, 146, 147 and 148 are substantially perpendicular to the ABS.
In some embodiments, the AC structure 140′′ extends from the ABS to the back of the pole 130′′, as is shown in FIG. 6. However, in other embodiments, the AFC structure may terminate between the ABS and the back of the pole 130′′. In some embodiments, at least the AFC structure 140′′ is fabricated by sputtering. For example, the layers 142, 144, 146, 147 and 148 may be sputter deposited. The remaining magnetic layers 132′′ and 134′′ of the pole 130′′ may be plated. In the embodiment shown, the magnetic moments of ferromagnetic layers 142, 146 and 148 are also perpendicular to the ABS, in the stripe height direction.
The magnetic head 100′′′ may have improved performance. The AC structure 140′′ may improve the stability of the return pole 130′′ and the read sensor as previously discussed. In addition, the use of additional layers 147 and 148 in the AFC structure 140′′ may enhance the antiferromagnetic coupling. The total magnetic moment of the return pole 130′′ may also be tailored. Thus, performance of the writer 120′′′ and reader 110′′′ may be enhanced.
FIG. 7 depicts a side view of an exemplary embodiment of a magnetic head 100′′′′. For clarity, FIG. 7 is not to scale. The magnetic recording head 100′′′′ is analogous to the magnetic heads 100, 100′, and 100′′ and 100′′′. Consequently, analogous components have similar labels. The magnetic recording head 100′′′′ thus includes a read transducer 110′′′′ and a writer transducer 120′′′′. The read transducer 110′′′′′ includes shield 112, AFC shield 116′ as well as a read sensor 114. The sensor 114 may be a GMR or TMR sensor. In other embodiments, other structures and other sensing mechanisms may be used for the sensor. The read transducer 110′′′′ may also include magnetic bias structures (not shown).
The shield 116′ for the magnetic read transducer 110′′′′ is an AFC shield analogous to the AFC shields previously shown. In the embodiment shown, the write transducer 120′′′′ and thus the return pole 130′′′ are separated from the AFC shield 116′ by a nonmagnetic piggyback layer 118. The nonmagnetic piggyback layer 118 is analogous to the piggyback layer depicted in previous drawings. However, in other embodiments, the piggyback layer 118 may be omitted.
The write transducer 120′′′′ includes a return pole 130′′′, coils 152 and 158, auxiliary pole(s) 154, back gap 150 and a main pole 156. Shield 160 may also be included. The components 130′′′, 150, 152, 154, 156, 158 and 160 in FIG. 7 are analogous to components 130/130′′, 150, 152, 154, 156, 158 and 160 depicted in previous drawings. In the embodiment shown, the return pole 130′′′ is coupled to the main pole 156 through a back gap 150. In other embodiments, the back gap 150 may be omitted.
The return pole 130′′′ thus includes an AC structure 140′′′ as well as optional additional magnetic layers 132′′′ and 134′′. In some embodiments, the additional magnetic layers 132′′′ and/or 134′′′ may be omitted. The layers 132′′′ and 134′′′ are ferromagnetic and may be formed of NiFe. The magnetic moments of the layers 132′′′ and 134′′′ are ferromagnetically coupled with the magnetic moments of the layers 142′ and 146′, respectively.
The AC structure 140′′′ includes two ferromagnetic layers 142′ and 146′ interleaved with and sandwiching nonmagnetic layer 144′. Other numbers of ferromagnetic layers and nonmagnetic layers may be used in other embodiments. As can be seen in FIG. 7, the magnetic moment of a ferromagnetic layer 142′ and 146′ is antiparallel to the magnetic moment of the nearest neighbor ferromagnetic layer. In some embodiments, the magnetic moments are antiferromagnetically coupled. Thus, the AC structure 140′′′ may be an AFC structure 140′′′. For example, the magnetic moments of the ferromagnetic layers 142′ and 146′ may be coupled through the nonmagnetic layer 142′. This coupling may be an RKKY coupling. The thicknesses and constituents of the layers 142′, 144′ and 146′ may be analogous to those shown in previous drawings. The layers 142′, 144′ and 146′ of the AC structure 140′′′ are substantially parallel to each other. In addition, the layers 142′, 144′ and 146′ are substantially perpendicular to the ABS.
In some embodiments, the AC structure 140′′′ extends from the ABS to the back of the pole 130′′′, as is shown in FIG. 7. However, in other embodiments, the AFC structure may terminate between the ABS and the back of the pole 130′′′. In some embodiments, at least the AFC structure 140′′′ is fabricated by sputtering. For example, the layers 142′, 144′ and 146′ may be sputter deposited. The remaining magnetic layers 132′′′ and 134′′′ of the pole 130′′′ may be plated.
The magnetic head 100′′′′ is substantially the same as the magnetic head 100′ depicted in FIGS. 3-4 except for the direction of the magnetic moments of the poles 130′′′ and 130′. In particular, the magnetic moments of the AC structure 140′′′ and the magnetic layers 132′′′ and 134′′′ are in the cross-track direction (perpendicular to the plane of the page).
The magnetic head 100′′′′ may have improved performance. The AC structure 140′′′ may improve the stability of the return pole 130′′′ and the read sensor as previously discussed. Thus, performance of the writer 120′′′′ and reader 110′′′′ may be enhanced. In addition, various features are highlighted in the magnetic recording heads 100, 100′, 100′′, 100′′′ and 100′′′′. However, various features of each of the magnetic recording heads 100, 100′, 100′′, 100′′′ and/or 100′′′′′ may be combined.
FIG. 8 is an exemplary embodiment of a method 200 for providing a magnetic recording head including a return pole having an AC structure. For simplicity, some steps may be omitted, interleaved, and/or combined. The method 200 is also described in the context of providing a magnetic recording head 100′ depicted in FIGS. 3-4. However, the method 200 may be used to fabricate multiple magnetic recording heads at substantially the same time. The method 200 may also be used to fabricate other magnetic recording heads including but not limited to any combination of 100, 100′, 100′′, 100′′′ and/or 100′′′. The method 200 is also described in the context of particular layers. A particular layer may include multiple materials and/or multiple sub-layers. The method 200 also may start after formation of other portions of the magnetic recording head.
A read transducer 110′ is provided, via step 202. Step 202 includes providing the shields 112 and 116′ as well as the sensor 114. Step 202 may include providing an AFC shield 116′. Thus, ferromagnetic layers interleaved with and sandwiching one or more nonmagnetic layers may be deposited in step 204. In addition, a magnetic field may be applied to align the magnetic moments of the ferromagnetic layers in the desired directions.
The piggyback layer 118 may optionally be provided in step 204. In other embodiments, step 204 may be omitted.
A write transducer is provided, via step 206. Step 206 includes providing a main pole 156, at least one coil 152/158 for energizing the main pole 156 and a return pole 130′ between the read sensor 114 and the main pole 156. The return pole 130′ including an AC pole structure 140′. The AC pole structure 140′ includes at least two ferromagnetic layers 142 and 146 interleaved with at least one nonmagnetic layer 144. In other embodiments, step 206 includes depositing another number of ferromagnetic and nonmagnetic layers. The layers 142, 144 and 146 may be deposited by sputtering in step 206. In addition, step 206 may include aligning the magnetic moments of the ferromagnetic layers in the desired direction. In some embodiments, step 206 includes providing the AC pole structure 140′ extending from the ABS to the back surface of the return pole 130′. Step 206 may also include depositing the magnetic layers 132′ and 134 for the return pole 130′. The back gap 150, auxiliary pole(s) 154, and shield 160 may also be provided in step 206.
Using the method 200, the magnetic head 100, 100′, 100′′, 100′′′ and/or 100′′′′ may be provided. Thus, the benefits of the magnetic head(s) 100, 100′, 100′′, 100′′′, and/or 100′′′′ may be achieved.
FIG. 9 is an exemplary embodiment of a method 210 for providing an AC structure for a return pole in a write transducer. For simplicity, some steps may be omitted, interleaved, and/or combined. The method 210 is also described in the context of providing a return shield 100′ depicted in FIGS. 3-4. However, the method 210 may be used to fabricate multiple return poles for multiple write transducers at substantially the same time. The method 210 may also be used to fabricate other return poles including but not limited to any combination of 130, 130′, 130′′, 130′′′ and/or 130′′′′. The method 210 is also described in the context of particular layers. A particular layer may include multiple materials and/or multiple sub-layers. The method 210 also may start after formation of other portions of the magnetic recording transducer. For example, the method 210 may start after the layer 132′ has been plated or otherwise deposited and terminate before the layer 134′ is plated or otherwise deposited.
A ferromagnetic layer 142 is deposited, via step 212. Step 212 may include sputtering a magnetic layer such as CoFe. However, in other embodiments, other materials may be used. The nonmagnetic layer 144 is deposited, via step 214. Step 214 may include sputtering a layer such as Ru. However, in other embodiments, other materials may be used. The ferromagnetic layer 146 is deposited, via step 216. Step 216 may include sputtering a magnetic layer such as CoFe. However, in other embodiments, other materials may be used. Steps 214 and 216 may optionally be repeated a desired number of times, via step 218. Thus, a desired number of ferromagnetic layers interleaved with and sandwiching nonmagnetic layers may be fabricated using the method 210. In some embodiments, the method 210 may include setting the desired direction of the magnetic moments, via step 220. Step 220 may be performed after the magnetic layer 134′ is deposited.
Using the method 210, the AC structure 140, 140′, 140′′ and/or 140′′′ may be provided. Thus, the return poles 130, 130′, 130′′ and/or 130′′′ may be formed. The magnetic heads 100, 100′, 100′′, 100′′′ and/or 100′′′′ may be provided. Thus, the benefits of the magnetic head(s) 100, 100′, 100′′, 100′′′, and/or 100′′′′ may be achieved.

## Claims

1. A magnetic head having an air-bearing surface (ABS) and comprising:
a read transducer including a first shield, a second shield and a read sensor between the first shield and the second shield, the second shield including a first ferromagnetic layer having a first magnetic moment, a nonmagnetic spacer layer, and a second ferromagnetic layer having a second magnetic moment, the nonmagnetic spacer layer residing between the first ferromagnetic layer and the second ferromagnetic layer, the first ferromagnetic layer residing between the read sensor and the nonmagnetic spacer layer, the first magnetic moment of the first ferromagnetic layer being coupled antiparallel with the second magnetic moment of the second ferromagnetic layer; and
a write transducer including a main pole, at least one coil for energizing the main pole and a return pole between the second shield of the read transducer and the main pole, the return pole including an antiparallel coupling (AC) pole structure, the AC pole structure including a plurality of ferromagnetic layers interleaved with at least one nonmagnetic layer, the plurality of ferromagnetic layers and the at least one nonmagnetic layer being substantially parallel, the plurality of ferromagnetic layers and the at least one nonmagnetic spacer layer being substantially perpendicular to the ABS, a magnetic moment of each of the plurality of ferromagnetic layers being aligned antiparallel with the magnetic moment of a nearest neighbor of the plurality of ferromagnetic layers;
wherein the return pole is magnetically decoupled from the second shield if the return pole does not adjoin the second shield; and
wherein at least one of the plurality of ferromagnetic layers is ferromagnetically coupled with the second ferromagnetic layer of the second shield if the return pole adjoins the second shield.

2. The magnetic head of claim 1 further comprising:
a nonmagnetic piggyback layer between the second shield and the return pole.

3. The magnetic head of claim 1 wherein the return pole further includes:
at least one magnetic layer adjacent to the AC pole structure.

4. The magnetic head of claim 1 wherein the return pole further includes:
a first magnetic layer and a second magnetic layer, the AC pole structure residing between the first magnetic layer and the second magnetic layer.

5. The magnetic head of claim 4 wherein the first magnetic layer and the second magnetic layer include NiFe.

6. The magnetic head of claim 1 wherein the write transducer further includes:
a back gap recessed from the ABS and coupling the main pole with the return pole.

7. The magnetic head of claim 1 wherein the return pole has an ABS facing surface and a back surface opposite to the ABS facing surface, the AC pole structure extending from the ABS facing surface to the back surface.

8. The magnetic head of claim 1 wherein the plurality of ferromagnetic layers includes a plurality of CoFe layers.

9. The magnetic head of claim 8 wherein each of the plurality of ferromagnetic layers has a thickness of at least fifty five nanometers and not more than eighty five nanometers.

10. The magnetic head of claim 1 wherein the at least one nonmagnetic layer includes Ru.

11. The head of claim 10 wherein each of the at least one nonmagnetic layer has a thickness of not more than ten Angstroms.

12. The magnetic head of claim 1 each of the plurality of ferromagnetic layers being antiferromagnetically coupled with a nearest neighbor of the plurality of ferromagnetic layers.

13. The magnetic transducer of claim 1 wherein the main pole is magnetically disconnected from the return pole.

14. A magnetic head having an air-bearing surface (ABS) and comprising:
a read transducer including a first shield, a second shield and a read sensor between the first shield and the second shield, the second shield including a first ferromagnetic layer having a first magnetic moment, a nonmagnetic spacer layer and a second ferromagnetic layer having a second magnetic moment, the nonmagnetic spacer layer residing between the first ferromagnetic layer and the second ferromagnetic layer, the first ferromagnetic layer residing between the read sensor and the nonmagnetic spacer layer, the first magnetic moment of the first ferromagnetic layer being coupled antiparallel with the second magnetic moment of the second ferromagnetic layer;
a nonmagnetic piggyback layer; and
a write transducer, the nonmagnetic piggyback layer being between the read transducer and the write transducer, the write transducer including a main pole, at least one coil for energizing the main pole, a back gap and a return pole between the read sensor and the main pole, the return pole including an ABS facing surface and a back surface opposite to the ABS facing surface, the return pole including an antiferromagnetic (AFC) pole structure and at least one NiFe magnetic layer adjoining the AFC pole structure, the AFC pole structure including a plurality of ferromagnetic layers interleaved with at least one nonmagnetic layer, the plurality of ferromagnetic layers and the at least one nonmagnetic layer being substantially parallel, the plurality of ferromagnetic layers and the at least one nonmagnetic spacer layer being substantially perpendicular to the ABS, a magnetic moment of each of the plurality of ferromagnetic layers being antiferromagnetically coupled with the magnetic moment of a nearest neighbor of the plurality of ferromagnetic layers, the AFC pole structure extending from the ABS facing surface to the back surface, the back gap recessed from the ABS and coupling the main pole with the return pole;
wherein the return pole is magnetically decoupled from the second shield.

15. A disk drive comprising:
a media;
a slider including a having an air-bearing surface (ABS) and including a read transducer and a write transducer, the read transducer including a first shield, a second shield and a read sensor between the first shield and the second shield, the second shield including a first ferromagnetic layer having a first magnetic moment, a nonmagnetic spacer layer, and a second ferromagnetic layer having a second magnetic moment, the nonmagnetic spacer layer residing between the first ferromagnetic layer and the second ferromagnetic layer, the first ferromagnetic layer residing between the read sensor and the nonmagnetic spacer layer, the first magnetic moment of the first ferromagnetic layer being coupled antiparallel with the second magnetic moment of the second ferromagnetic layer, the write transducer including a main pole, at least one coil for energizing the main pole and a return pole between the read sensor and the main pole, the return pole including an antiparallel (AC) pole structure, the AC pole structure including a plurality of ferromagnetic layers interleaved with at least one nonmagnetic layer, the plurality of ferromagnetic layers and the at least one nonmagnetic layer being substantially parallel, the plurality of ferromagnetic layers and the at least one nonmagnetic spacer layer being substantially perpendicular to the ABS, a magnetic moment of each of the plurality of ferromagnetic layers being aligned antiparallel with the magnetic moment of a nearest neighbor of the plurality of ferromagnetic layers;
wherein the return pole is magnetically decoupled from the second shield if the return pole does not adjoin the second shield; and
wherein at least one of the plurality of ferromagnetic layers is ferromagnetically coupled with the second ferromagnetic layer of the second shield if the return pole adjoins the second shield.

16. The disk drive of claim 15 wherein the main pole is magnetically disconnected from the return pole.