HK1154115B - Method and system for providing a magnetic transducer having an improved read sensor - Google Patents

Description

Method and system for providing a magnetic transducer with an improved read sensor

Technical Field

Background

FIG. 1 illustrates a portion of a conventional magnetic transducer 10, such as a conventional read transducer or other device. The conventional transducer 10 is located on a conventional substrate 11, such as an AlTiC substrate. The conventional transducer 10 includes a conventional bottom shield 12, a conventional sensor 20, and a conventional top shield 40. The transducer 10 also typically includes one or more seed layers (not shown) between the conventional AFM layer 22 and the conventional shield 12. Conventional shields 12 and 40 typically comprise NiFe and are formed by electroplating. Sensor 20 is shown in a current-perpendicular-to-plane (CPP) configuration. In the CPP configuration, the read current is typically driven perpendicular to the plane of the layers of the device along the z-axis as shown.

The conventional sensor 20 includes a conventional Antiferromagnetic (AFM) layer 22, a conventional Synthetic Antiferromagnetic (SAF) layer 24, a conventional barrier layer 32 and a conventional free layer 34, and may include a conventional capping layer 36. The conventional free layer 34 has a magnetization that is substantially free to change direction in response to an applied magnetic field, e.g., a magnetic field from a bit being read. Conventional barrier layer 32 may allow conduction through sensor 20 via tunneling. Thus, the sensor 20 is a Tunneling Magnetoresistive (TMR) sensor. Note that if a conductive spacer layer is used in place of barrier layer 32, then sensor 20 is a spin valve. The conventional SAF layer 24 typically includes two ferromagnetic layers 26 and 30 separated by a nonmagnetic spacer layer 28. The ferromagnetic layers are typically antiferromagnetically coupled. One or more magnetizations of the conventional SAF layer 24 are pinned or fixed by the conventional AFM layer 22. More specifically, the first ferromagnetic layer 26, which is commonly referred to as the pinned layer or the fixed layer, has a ferromagnetic layer passing throughThe conventional AFM layer 22 is pinned in magnetization, for example, via exchange interaction. The remaining ferromagnetic layer or reference layer 30 has its magnetization pinned because it is strongly magnetically coupled to the pinned layer 26. The conventional pinned layer 26 is typically made of, for example, Co₉₀Fe₁₀A single layer of the composition. Other conventional pinned layers 26 may be made of Co₇₅Fe₂₅And (4) forming.

Although the conventional sensor 20 may function, the conventional transducer 10 may have limited utility. For example, when the conventional read sensor 20 is used in a CPP configuration, baseline popping (BLP) and/or baseline noise (BLN) may occur in the conventional read sensor 20. BLP refers to a time domain random noise spike above the noise baseline. BLN refers to a high overall noise baseline. Both BLP and BLN have large frequency bandwidths, typically from KHz to GHz. The presence of BLP and BLN adversely affects the signal-to-noise ratio of conventional converter 10 and, therefore, the performance of conventional converter 10. BLP and BLN may also be the primary failure modes in hard disk drive applications of conventional sensor 20. Because BLN and BLP may be failure modes, they may also adversely affect the reliability of conventional sensor 20. Thus, the use of the conventional converter 10 may have drawbacks.

Accordingly, there is a need for a system and method for providing a converter with improved performance.

Disclosure of Invention

A method and system for providing a magnetic structure in a magnetic transducer is described. The method and system include providing a pinned or fixed layer, a synthetic antiferromagnetic medium (SAF) adjacent to the pinned layer, a nonmagnetic layer, and a sensor layer. The SAF is located between the nonmagnetic layer and the pinned layer. The nonmagnetic layer is between the SAF and the sensor layer. The SAF includes a pinned layer, a reference layer, and a nonmagnetic spacer layer between the pinned layer and the reference layer. The pinned layer is magnetically coupled to the reference layer and includes a plurality of sublayers. A first sub-layer of the plurality of sub-layers has a first cutoff temperatureDistribution T_BDAnd a first exchange energy. A second sub-layer of the plurality of sub-layers has a second T_BDAnd a second exchange of energy. The first sublayer is between the pinning layer and the second sublayer. First T_BDGreater than a second T_BDAnd the first exchange energy is less than the second exchange energy.

Drawings

FIG. 1 is a schematic diagram of a portion of a conventional transducer including a conventional sensor;

FIG. 2 illustrates an exemplary embodiment of a magnetic head having a transducer including an exemplary embodiment of a magnetic structure;

FIG. 3 illustrates an exemplary embodiment of a portion of a transducer including an exemplary embodiment of a magnetic structure;

FIG. 4 illustrates another exemplary embodiment of a portion of a transducer including an exemplary embodiment of a magnetic structure;

FIG. 5 illustrates another exemplary embodiment of a portion of a transducer including an exemplary embodiment of a magnetic structure; and

FIG. 6 illustrates an exemplary embodiment of a method of forming a portion of a transducer including an exemplary embodiment of a magnetic structure.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

FIG. 2 shows a magnetic head 100. The head includes a magnetic read transducer 110 and a write transducer 140. FIG. 3 illustrates an exemplary embodiment of a magnetic structure 130 that may be used as a read sensor of the magnetic head 100. However, in other embodiments, the magnetic structure 130 may be used for other purposes. Further, the magnetic structure 130 is shown in a CPP configuration, and thus is connected to the shields 112 and 122. However, in another embodiment, a gap may exist between the magnetic structure 130 and the shield 112 and/or 122. Referring to fig. 2-3, in another embodiment, the head 100 may include only the read transducer 110. The head 110 may be located on a slider (not shown) of a disk drive (not shown). The head 100 is also described in the context of a particular layer. However, in some embodiments, such layers may include one or more sub-layers. For clarity, fig. 2-3 are not drawn to scale.

Write transducer 140 includes a first pole 142, an auxiliary pole 146, a main pole 148, a write gap 150, coils 144 and 152, and a return shield 154. However, in another embodiment, the write transducer 140 may include other and/or different components. Furthermore, in various embodiments, one or more portions of the write transducer 140 may be omitted.

The read transducer 110 includes shields 112 and 122 and a read sensor/magnetic structure 130. Further, although only one magnetic structure 130 is shown, multiple magnetic structures may be present. Further, although the magnetic structure 130 is used as a read sensor in transducer 100, the magnetic structure 130 may be used for other purposes in another transducer. Furthermore, as clearly shown in FIG. 3, the magnetic structure 130 includes a pinned or fixed layer 160, a SAF170, a nonmagnetic layer 190, and a free layer 192. In some embodiments, other components may be included as part of the magnetic structure 130. For example, the magnetic structure 130 may also include one or more seed layers and/or capping layers.

The free layer 192 includes one or more ferromagnetic layers (not separately shown in fig. 3). At least some of these ferromagnetic layers may be separated by nonmagnetic layers. In the embodiment shown in FIG. 3, the free layer 192 is the sensor layer for the head 100. Thus, the free layer 192 is hereinafter referred to as the sensor layer 192. The nonmagnetic layer 190 separates the sensor layer 192 from the SAF 170. In some embodiments, the non-magnetic layer 190 is an insulating tunneling barrier (tunneling barrier). For example, the nonmagnetic layer 190 may be a crystalline tunneling barrier layer. In some such embodiments, the crystalline tunneling barrier layer may include or consist of crystalline MgO. In other embodiments, nonmagnetic layer 190 may be conductive and/or have another structure. The pinning layer 160 pins the magnetization of the SAF 170. The pinning layer 160 may be an AFM layer, such as IrMn, that pins or fixes the magnetization of the pinned layer or fixed layer 172 through exchange interaction. However, in other embodiments, the pinning layer 160 may be another material and/or have other properties.

The SAF170 is adjacent to the pinning layer 160. The SAF170 includes a pinned layer 172 adjacent to the pinning layer 160, a reference layer 182, and a nonmagnetic spacer layer 180 between the pinned and reference layers. The pinned layer 172 is magnetically coupled to the reference layer 182. In some embodiments, the magnetizations of the pinned layer and the reference layer are antiferromagnetically coupled. Although shown as a single ferromagnetic layer, the reference layer 182 may include multiple sublayers. It is also desirable that the nonmagnetic spacer layer 182 be electrically conductive. For example, a material such as Ru may be used for the nonmagnetic spacer layer 180.

The pinned layer 172 includes sublayers. In the embodiment shown in fig. 3, there are two sublayers 174 and 176. However, in other embodiments, additional sub-layers (not shown in fig. 3) may be provided. The first sublayer 174 has a first cutoff temperature profile (T)_BD) And a first exchange energy. The second sublayer 176 has a second T_BDAnd a second exchange of energy. T of a layer_BDIs a measure of the degree of disorder of the magnetic layer at high temperatures. More specifically, T_BDAnd therefore corresponds to a temperature at which a specified proportion of the magnetic layers are no longer pinned by the pinning layer 160. For example, in some embodiments, T_BDIs the temperature at which at least ten percent of the magnetic layer is no longer fixed or pinned by the fixed or pinned layer 160. Generally, a higher T is desired_BD. Exchange energy is a measure of the pinning strength due to the interaction between a particular magnetic layer and the ARM layer. The sublayers 174 and 176 are configured such that the first T of the first sublayer 174_BDA second T greater than the second sublayer 176_BD. In some embodiments, sublayers 174 and 176 are also configured such that the first T_BDAnd a second T_BDAre greater than or equal to 270 degrees celsius. Conversely, the first exchange energy of the first sublayer 174 is less than the second exchange energy of the second sublayer 176. The desired exchange energy is at least equal to 0.3 molGrid/cm²(erg/cm²). In some such embodiments, the exchange energy is at least equal to 0.4erg/cm². For example, in some embodiments, the first sublayer 174 comprises Co_1-xFe_xAnd the second sublayer 176 comprises Co_1-yFe_yWherein x is greater than 0 and not greater than 0.15, and y is not less than 0.2 and not greater than 0.5. In some such embodiments, x is at least equal to 0.05, and y is at least equal to 0.25 and no greater than 0.35. The first sublayer 174 and the second sublayer 176 can also comprise different compositions. For example, the first sublayer may comprise Co_1-v-wFe_vB_wWherein v is greater than 0, w is greater than 0, and v + w is less than 1. In such an embodiment, the second sublayer 176 may comprise Co as described above_1-yFe_y。

Except for the configuration T_BDAnd exchange energy, the thickness of the sub-layers 174 and 176 may also be selected. In some embodiments, first sublayer 174 has a thickness at least equal to 3 angstroms and no greater than 20 angstroms. Likewise, the second sublayer 176 has a thickness at least equal to 3 angstroms and no greater than 20 angstroms. In some embodiments, the first sublayer 174 and the second sublayer have the same thickness. However, in other embodiments, their thicknesses are different. For example, the second sublayer 176 may be thicker than the first sublayer 174. In some embodiments, for example, the first sub-layer 174 may have a thickness at least equal to 3 angstroms and no greater than 7 angstroms, while the second sub-layer 176 has a thickness at least equal to 8 angstroms and no greater than 12 angstroms.

In addition to the properties described above, it is desirable that the pinned layer 172 have low scattering. Scattering is a measure of the spread of the magnetic moments of the particles in the magnetic layer around the magnetization direction of the magnetic layer. The magnetic moment in the low scattering indicator layer more closely coincides with the net magnetization of the layer. Thus, in addition to T as described above_BDAnd exchange energy, it is desirable that the sublayers 174 and 176 provide the pinned layer 172 with as low scattering as possible.

The use of the magnetic structure 130 including the pinned layer 172 of the SAF170 may improve the performance of the transducer 110. Since each of the sublayers 174 and 176 is selected to have the above-mentioned T_BDAnd exchangeEnergy, and thus the pinned layer 172 may have a higher exchange energy and a higher T_BDA desired combination of (a). Further, the sublayers 174 and 176 may be configured such that the pinned layer 172 has lower scattering than may be available. Thus, the pinning layer 160 may be better able to pin the magnetization of the pinned layer 172. Thus, the magnetization of the pinned layer 172 may be made more stable. The reference layer 182 is magnetically coupled to the pinned layer 172. Thus, the magnetization of the reference layer 182 may also be more stable. It has been determined that the BLP and BLN described above may be due, at least in part, to magnetic instability in the SAF 170. Improved pinning of the pinned layer 172 and thus the reference layer 182 may reduce magnetic fluctuations in the SAF 170. The improvement in stability in the SAF170 may reduce BLP and BLN. The improved stability may also allow for greater robustness of the magnetic structure 170 against stresses during manufacture or use in a drive. Furthermore, when the magnetic structure 130 is used in the head 100, the magnetic structure 130 may result in an improved roll-off field. Accordingly, performance, reliability, and yield or yield (yield) of the magnetic structure 130 and the head 100 may be improved.

FIG. 4 illustrates another exemplary embodiment of a portion of a transducer 110 'including an exemplary embodiment of a magnetic structure 130'. The portions of transducer 110' are similar to those of head 100 and structure 130 shown in fig. 2-3. Such similar structures are similarly labeled. Thus, magnetic structure 130 ' includes pinning layer 160 ', SAF170 ', nonmagnetic layer 190 ', and sensor layer 192 ' that are similar to pinning layer 160, SAF170, nonmagnetic layer 190, and sensor layer 192, respectively. In the illustrated embodiment, other components may be included as part of the magnetic structure 130'. For example, the magnetic structure 130' also includes one or more seed layers 162 and one or more capping layers 196. Thus, the magnetic structure 130' may be used as a read sensor for the magnetic head 100. However, in other embodiments, the magnetic structure 130' may be used for other purposes. Further, the magnetic structure 130 ' is shown in a CPP configuration, and is thus connected to shields 112 ' and 122 ' on the substrate 111. However, in another embodiment, there may be a gap between the magnetic structure 130 ' and the shield 112 ' and/or 122 '. Structure 130' is also described in the context of a particular layer. However, in some embodiments, such layers may include one or more sub-layers. For clarity, FIG. 4 is not drawn to scale.

The SAF 170' is similar to the SAF 170. Thus, the SAF170 ' includes sublayers 174 ' and 176 '. In the embodiment shown in FIG. 4, an additional sublayer 178 is present. In other embodiments, other sub-layers (not shown in FIG. 4) may be provided. The first sublayer 174' has a first T_BDAnd a first exchange energy. The second sublayer 176' has a second T_BDAnd a second exchange of energy. The third sublayer 178 has a third T_BDAnd a third exchange of energy.

The sublayers 174 ', 176 ', and 178 are configured such that the first T of the first sublayer 174 ' is_BDA second T larger than the second sublayer 176_BD. In some embodiments, the third sublayer 178 is configured such that the third T_BDGreater than a second T_BD. In some embodiments, sublayers 174 ', 176', and 178 are also configured such that first T_BDA second T_BDAnd a third T_BDGreater than or equal to 270 degrees celsius. Conversely, the first exchange energy of the first sublayer 174 'is less than the second exchange energy of the second sublayer 176'. In some embodiments, the third sublayer 178 is configured such that the third exchange energy is less than the second exchange energy. The exchange energy is expected to be at least equal to 0.3erg/cm². In some such embodiments, the exchange energy is at least equal to 0.4erg/cm². In some embodiments, the third sublayer 178 is configured to have a T substantially equal to the first sublayer 174_BDAnd exchanging energy. However, in other embodiments, the third sublayer 178 may have a different T than the first sublayer 174_BDAnd/or exchange energy.

For example, in some embodiments, each of the first sublayer 174' and the third sublayer 178 comprises Co_1-xFe_x. In such an embodiment, the second sublayer 176' may comprise Co_1-yFe_yWherein x is greater than 0 and not more than 0.15, and y is not less than 0.2 and not more than 0.5. In some of these embodiments, the first and second electrodes are,x is at least equal to 0.05 and y is at least equal to 0.25 and not more than 0.35. The first, second, and third sub-layers 174 ', 176', 178 may also include different compositions. For example, the first sublayer 174' may comprise Co_1-v-wFe_vB_wWherein v is greater than 0, w is greater than 0, and v + w is less than 1. As described above, in such embodiments, the second sublayer 176 may comprise Co_1-yFe_yAnd the third sublayer 178 may comprise Co_1-v-wFe_vB_wAnd/or Co_1-xFe_x。

Except for the configuration T_BDAnd exchanging energy, the thicknesses of the sub-layers 174 ', 176', and 178 may also be selected. In some embodiments, the first sub-layer 174' has a thickness at least equal to 3 angstroms and no greater than 20 angstroms. Likewise, the second sublayer 176' may have a thickness at least equal to 3 angstroms and no greater than 20 angstroms. The thickness of the third layer 178 can be greater than 0 angstroms and not greater than 10 angstroms. In some embodiments, the first, second, and third sub-layers 174 ', 176', 178 have the same thickness. However, in other embodiments, their thicknesses are different. For example, the second sublayer 176 'may be thicker than the first sublayer 174' and the third sublayer 178. In such embodiments, the first sublayer 174' and the third sublayer 178 may or may not have the same thickness. In some embodiments, for example, each of the first and third sub-layers 174 ', 178 may have a thickness at least equal to 3 angstroms and no greater than 7 angstroms, while the second sub-layer 176' has a thickness at least equal to 8 angstroms and no greater than 12 angstroms.

In addition to the features described above, it is desirable that the pinned layer 172' have low scattering. Thus, in addition to T as described above_BDAnd exchanging energy, it is desirable that the sublayers 174 ', 176 ', and 178 provide the pinned layer 172 ' with as low a dispersion as possible.

The use of the magnetic structure 130 'including the pinned layer 172' of the SAF170 'may improve the performance of the transducer 110'. The transducer 110 'and the magnetic structure 130' may have the benefits described above with respect to the transducer 110 and the magnetic structure 130. Furthermore, the use of the third sublayer 178 may improve the asymmetry of the magnetic structure 130'.

FIG. 5 illustrates another exemplary embodiment of a portion of a transducer 110 "that includes an exemplary embodiment of a magnetic structure 130". The portions of transducer 110 "are similar to the portions of head 100, transducer 110/110 'and structure 130' shown in fig. 2-4. Such similar structures are similarly labeled. Thus, the magnetic structure 130 "includes pinning layers 160", SAF170 ", nonmagnetic layer 190", and sensor layer 192 "that are similar to the pinning layers 160/160 ', SAF 170/170', nonmagnetic layer 190/190 ', and sensor layer 192/192', respectively. In the illustrated embodiment, other components may be included as part of the magnetic structure 130 ". For example, the magnetic structure 130 "also includes one or more seed layers 162 'and one or more capping layers 196'. Thus, the magnetic structure 130 "may be used as a read sensor for the magnetic head 100. However, in other embodiments, the magnetic structure 130 "may be used for other purposes. Further, the magnetic structure 130 "is shown in a CPP configuration, and is thus connected to shields 112" and 122 "located on the substrate 111'. However, in another embodiment, there may be a gap between the magnetic structure 130 "and the shield 112" and or 122 ". The structure 130 "is also described in the context of a particular layer. However, in some embodiments, such layers may include one or more sub-layers. For clarity, FIG. 5 is not drawn to scale.

The SAF170 "is similar to the SAF 170/170'. Thus, the SAF170 "includes sub-layers 174", 176 ", and 178'. T of sub-layers 174 ', 176' and 178_BDThe relationship with the exchange energy may be with the T of sublayers 174/174 ', 176/176', and 178_BDThe same relationship as between the exchanged energy. In addition, the SAF170 "includes a fourth sublayer 179. The fourth sublayer 179 includes a fourth T_BDAnd a fourth exchange energy. In some embodiments, the fourth T_BDIs less than the first T_BDAnd a third T_BD. The fourth exchange energy is greater than the first exchange energy and the third exchange energy. Thus, the fourth layer 179 may be similar to the second sublayer 176 ″. Thus, the pinned layer 172 "may be considered to include two bilayers. The first bilayer includes a first sublayer 174' and a second sublayer176". The second bilayer includes a third sublayer 178' and a fourth sublayer 179. Sublayers 174 ", 176", and 178 ' have compositions similar to the compositions of sublayers 174/174 ', 176/176 ', and 178. Furthermore, the fourth sublayer 179 may comprise Co_1-uFe_uWherein u is not less than 0.2 and not more than 0.5. In some such embodiments, u is at least equal to 0.25 and no greater than 0.35.

Except for the configuration T_BDExchanging energy and composition, the thickness of the sub-layers 174 ", 176", 178' and 179 may also be selected. Sublayers 174 ", 176", and 178 ' have thicknesses similar to those of 174/174 ', 176/176 ', and 178. In addition to the features described above, it is desirable that the pinned layer 172 "have low scattering. Thus, in addition to T as described above_BDAnd exchange energy, it is desirable that the sublayers 174 ", 176", 178', and 179 provide the pinned layer 172 "with as little scattering as possible.

The use of the magnetic structure 130 "including the pinned layer 172" of the SAF170 "may improve the performance of the transducer 110". The transducer 110 "and the magnetic structure 130" may have the benefits described above with respect to the transducer 110/110 'and the magnetic structure 130/130'.

FIG. 6 illustrates an exemplary embodiment of a method 300 for forming a portion of a transducer including an exemplary embodiment of a magnetic structure. Some steps are omitted and/or combined for clarity. The method 300 is described in the context of the transformers 110/110'/110 ". However, the method 300 may be used with other converters. The method 300 may also begin after other structures of the read transducer and/or the write transducer are formed. The method 300 is also described in the context of providing a single magnetic structure 130/130'/130 ". However, the method 300 may be used to fabricate multiple structures substantially simultaneously. The method 300 and structures such as the transformer 110/110'/110 "are also described in the context of particular layers. However, in some embodiments, such layers may include one or more sub-layers. The method 300 begins after the pinned layer 160/160'/160 "is provided.

One or more materials for the first sub-layer 174/174 '/174 "are provided over the pinned layer 160/160'/160", via step 302. One or more materials for the second sub-layers 176/176 '/176 "are deposited over the first pinned layers 174/174'/174", via step 304. One or more materials for any additional sub-layers, such as sub-layers 178/178' and 179, are provided, via step 306. Thus, in steps 302, 304, and 306, the material for the pinning layer 172/172'/172 "is provided. One or more materials for non-magnetic separation layer 180/180'/180 "are provided, via step 308. One or more materials of the reference layer 182/182'/182 "are provided, via step 310. Thus, in steps 302, 304, 306, 308, and 310, the material for the SAF 170/170'/170 "is provided. One or more materials for the nonmagnetic layer 190/190'/190 "are provided, via step 312. The material for the sensor layers 192/192'/192 "is deposited, via step 314. In addition, one or more materials of the cover layer may also be provided.

Thus, through steps 302 through 314, a stack for the magnetic structures 130/130'/130 "is provided. The magnetic structure 130 is defined, via step 316. Step 316 may include providing a mask of the stack and milling the exposed portion. The manufacture of the transducers 110/110'/110 "may be completed, via step 318. Thus, by using the method 300, the benefits of the converters 110, 110', and 110 "can be realized.

Claims (35)

1. A magnetoresistive structure configured for use in a magnetic transducer, comprising:

a pinning layer;

a Synthetic Antiferromagnetic (SAF) adjacent to the pinned layer, the SAF including a pinned layer magnetically coupled to a reference layer and including a plurality of sublayers, a reference layer, and a nonmagnetic spacer layer between the pinned layer and the reference layer, a first sublayer of the plurality of sublayers having a first cut-off temperature profile, i.e., a first T_BDAnd a first exchange energy, the plurality of sub-unitsThe second sub-layer in the layer has a second T_BDAnd a second exchange energy, the first sublayer located between the pinned layer and the second sublayer, the first T_BDIs greater than the second T_BDThe first exchange energy is less than the second exchange energy;

a nonmagnetic layer, the SAF being located between the nonmagnetic layer and the pinned layer; and

a sensor layer, the nonmagnetic layer being between the SAF and the sensor layer.

2. The magnetoresistive structure of claim 1, wherein the nonmagnetic layer comprises an insulating tunneling barrier layer.

3. The magnetoresistive structure of claim 1, wherein the first sublayer comprises Co_1-xFe_xAnd the second sublayer comprises Co_1-yFe_yWherein x is greater than 0 and not more than 0.15, and y is not less than 0.2 and not more than 0.5.

4. A magnetoresistive structure according to claim 3, wherein x is at least equal to 0.05 and y is at least equal to 0.25 and not more than 0.35.

5. The magnetoresistive structure of claim 3, wherein the first sublayer has a first thickness and the second sublayer has a second thickness, the first thickness being at least equal to 3 angstroms and not greater than 20 angstroms, the second thickness being at least equal to 3 angstroms and not greater than 20 angstroms.

6. The magnetoresistive structure of claim 5, wherein the second thickness is greater than the first thickness.

7. The magnetoresistive structure of claim 1, wherein the plurality of sub-layers further includes a third sub-layer having a third T_BDAnd the third intersectionAnd (6) exchanging energy.

8. A magnetoresistive structure according to claim 7, wherein the third T_BDIs greater than the second T_BDAnd the third exchange energy is less than the second exchange energy.

9. A magnetoresistive structure according to claim 8, wherein the third exchange energy is substantially equal to the first exchange energy, and the third T is_BDSubstantially corresponding to said first T_BDAre equal.

10. The magnetoresistive structure of claim 8, wherein the first sublayer comprises Co_1-xFe_xThe second sublayer comprising Co_1-yFe_yAnd the third sublayer comprises Co_1-xFe_xWherein x is greater than 0 and not more than 0.15, and y is not less than 0.2 and not more than 0.5.

11. The magnetoresistive structure of claim 10, wherein x is at least equal to 0.05 and y is at least equal to 0.25 and not greater than 0.35.

12. The magnetoresistive structure of claim 10, wherein the first sublayer has a first thickness, the second sublayer has a second thickness, and the third sublayer has a third thickness, the first thickness is at least equal to 3 angstroms and no greater than 20 angstroms, the second thickness is at least equal to 3 angstroms and no greater than 20 angstroms, and the third thickness is greater than 0 angstroms and no greater than 10 angstroms.

13. The magnetoresistive structure of claim 12, wherein the second thickness is greater than the first thickness and the third thickness.

14. The magnetoresistive structure of claim 8, wherein the plurality of sub-carriersThe layer further includes a fourth sublayer having a fourth T_BDAnd a fourth exchange energy.

15. The magnetoresistive structure of claim 1, wherein the pinned layer comprises Co_1-xFe_xAnd Co_1-y-zFe_yB_zWherein x is greater than 0 and less than 1, y is greater than 0, z is greater than 0 and y + z is less than 1.

16. The magnetoresistive structure of claim 15, wherein the first sublayer comprises Co_1-y-zFe_yB_z。

17. The magnetoresistive structure of claim 1, wherein the pinned layer comprises an antiferromagnetic layer.

18. A magnetic head, comprising:

a read transducer comprising a read sensor, the read sensor further comprising a pinned layer, a Synthetic Antiferromagnetic (SAF) medium adjacent to the pinned layer, a nonmagnetic layer, and a sensor layer, the SAF being between the nonmagnetic layer and the pinned layer, the nonmagnetic layer being between the SAF and the sensor layer, the SAF comprising a pinned layer magnetically coupled to the reference layer and comprising a plurality of sub-layers, a first sub-layer of the plurality of sub-layers having a first cut-off temperature profile, a first T_BDAnd a first exchange energy, a second sublayer of the plurality of sublayers having a second T_BDAnd a second exchange energy, the first sublayer located between the pinned layer and the second sublayer, the first T_BDIs greater than the second T_BDThe first exchange energy is less than the second exchange energy.

19. The head as recited in claim 18, wherein the first sublayer includes Co_1-xFe_xAnd the second sublayer comprises Co_1-yFe_yWherein x is greater than 0 and not more than 0.15, and y is not less than 0.2 and not more than 0.5.

20. The head as recited in claim 18, wherein x is at least equal to 0.05 and y is at least equal to 0.25 and not greater than 0.35.

21. The head as recited in claim 18, wherein the first sub-layer has a first thickness and the second sub-layer has a second thickness, the first thickness being at least equal to 3 angstroms and no greater than 20 angstroms, the second thickness being at least equal to 3 angstroms and no greater than 20 angstroms.

22. The head as recited in claim 18, wherein the plurality of sub-layers further includes a third sub-layer having a third T_BDAnd a third exchange energy, said third T_BDIs greater than the second T_BDThe third exchange energy is less than the second exchange energy.

23. The head as recited in claim 22, wherein the first sublayer includes Co_1-xFe_xThe second sublayer comprising Co_1-yFe_yAnd the third sublayer comprises Co_1-xFe_xWherein x is greater than 0 and not more than 0.15, and y is not less than 0.2 and not more than 0.5.

24. A magnetic head as claimed in claim 23, wherein x is at least equal to 0.05 and y is at least equal to 0.25 and not more than 0.35.

25. The head as recited in claim 23, wherein the first sublayer has a first thickness, the second sublayer has a second thickness, and the third sublayer has a third thickness, the first thickness being at least equal to 3 angstroms and no greater than 20 angstroms, the second thickness being at least equal to 3 angstroms and no greater than 20 angstroms, and the third thickness being greater than 0 angstroms and no greater than 10 angstroms.

26. The head as recited in claim 18, further comprising:

and writing into the transducer.

27. A disk drive comprising:

a slider; and

a magnetic head as claimed in claim 18.

28. A method for fabricating a magnetoresistive structure for use in a magnetic transducer, the method comprising:

providing a pinning layer;

providing a Synthetic Antiferromagnetic (SAF) adjacent to the pinned layer, the SAF including a pinned layer magnetically coupled to a reference layer and including a plurality of sub-layers, a first one of the sub-layers having a first cut-off temperature profile, a first T_BDAnd a first exchange energy, a second sublayer of the plurality of sublayers having a second T_BDAnd a second exchange energy, the first sublayer located between the pinned layer and the second sublayer, the first T_BDIs greater than the second T_BDThe first exchange energy is less than the second exchange energy;

providing a nonmagnetic layer, the SAF being located between the nonmagnetic layer and the pinned layer;

providing a sensor layer, the nonmagnetic layer being between the SAF and the sensor layer; and

forming patterns of the magnetoresistive structure in the pinning layer, the SAF, the nonmagnetic layer, and the sensor layer.

29. The method of claim 28, wherein the first sublayer comprises Co_1-xFe_xAnd the second sublayer comprises Co_1-yFe_yWherein x is greater than 0 and not more than 0.15, and y is not less than 0.2 and not more than 0.5.

30. The method of claim 29, wherein x is at least equal to 0.05 and y is at least equal to 0.25 and not greater than 0.35.

31. The method of claim 29, wherein the first sub-layer has a first thickness and the second sub-layer has a second thickness, the first thickness being at least equal to 3 angstroms and not greater than 20 angstroms, the second thickness being at least equal to 3 angstroms and not greater than 20 angstroms.

32. The method of claim 28, wherein the plurality of sub-layers further comprises a third sub-layer having a third T_BDAnd a third exchange energy, said third T_BDIs greater than the second T_BDThe third exchange energy is less than the second exchange energy.

33. The method of claim 32, wherein the first sublayer comprises Co_1-xFe_xThe second sublayer comprising Co_1-yFe_yAnd the third sublayer comprises Co_1-xFe_xWherein x is greater than 0 and not more than 0.15, and y is not less than 0.2 and not more than 0.5.

34. The method of claim 33, wherein x is at least equal to 0.05 and y is at least equal to 0.25 and not greater than 0.35.

35. The method of claim 33, wherein the first sublayer has a first thickness, the second sublayer has a second thickness, and the third sublayer has a third thickness, the first thickness is at least equal to 3 angstroms and no greater than 20 angstroms, the second thickness is at least equal to 3 angstroms and no greater than 20 angstroms, and the third thickness is greater than 0 angstroms and no greater than 10 angstroms.