Patent Publication Number: US-7916433-B2

Title: Magnetic element utilizing free layer engineering

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present invention is a divisional application of U.S. patent application Ser. No. 11/487,552 entitled MAGNETIC ELEMENT UTILIZING FREE LAYER ENGINEERING filed on Jul. 14, 2006 and assigned to the assignee of the present application. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to magnetic recording and memory systems, and more particularly to a method and system for providing a magnetic element having a large magnetoresistive signal and that may be suitable in magnetic media for example in a hard disk drive and applications utilizing magnetic elements that can be changed or switched using a spin transfer effect for example in microwave generator applications. 
     BACKGROUND OF THE INVENTION 
       FIG. 1  depicts a conventional magnetic element  10 , which is a conventional magnetic tunneling junction (MTJ). Such a conventional MTJ  10  can be used in magnetic media such as for a hard disk drive (HDD) as well as in other applications. In some applications, such as in a HDD, the magnetization state of the conventional MTJ  10  may be changed by applying an external field, for example using a recording head (not shown). The magnetization state of the conventional MTJ  10  may also be changed using the spin transfer effect, for example in applications such as microwave generators. 
     The conventional MTJ  10  typically resides on a substrate (not shown), uses seed layer(s)  11  and includes a conventional antiferromagnetic (AFM) layer  12 , a conventional pinned layer  14 , a conventional barrier layer  16 , a conventional free layer  18 , and a conventional capping layer  20 . The conventional pinned layer  14  and the conventional free layer  18  are ferromagnetic. The ferromagnetic layers  14  and  18  typically include materials from the group of Ni, Co, and Fe and their alloys, such as CoFe, CoFeNi, a low-moment ferromagnetic materials. For example materials such as FeCoB, with B from five through thirty atomic percent are used. Although depicted as simple (single) layers, the pinned layer  14  and free layer  18  may include multiple layers. For example, the pinned layer  14  and/or the free layer  18  may include two ferromagnetic layers antiferromagnetically coupled through a thin Ru layer via RKKY exchange interaction—forming a synthetic antiferromagnetic (SAF) layer. For example, a layer of CoFeB separated by a thin layer of Ru may be used for the conventional pinned layer  14  and/or the conventional free layer  18 . The thin layer of Ru may, for example be between three and eight Angstroms thick. The conventional free layer  18  is typically thinner than the conventional pinned layer  14 , and has a changeable magnetization  19 . The saturation magnetization of the conventional free layer  18  is typically adjusted between four hundred and one thousand four hundred emu/cm 3  by varying the composition of elements. The magnetization  15  of the conventional pinned layer  14  is fixed, or pinned, in a particular direction, typically by an exchange-bias interaction with the AFM layer  12 . 
     In order to use the conventional MTJ  10  in certain applications, such as in a HDD, a signal that is large in comparison to external field variations is desired. Thus, a high magnetoresistance is also desirable. For HDD applications, a low RA is also desirable. The low RA is considered to be critical in both reducing noise and allowing an impedance match of the conventional MTJ to an external sense amplifier (not shown) in the read head (not shown). An improved magnetic performance will also benefit process control of switching current distribution. 
     Such a combination of a high magnetoresistance and a low RA has been achieved in conventional MTJs that use MgO as the conventional barrier layer  16 . For example, it has been shown that a magnetoresistance (ΔR/R) of 150% with an RA as low as 3Ωμm 2  can be realized for such a conventional MTJ  10  that uses an MgO for the conventional barrier layer  16  in combination with CoFeB for the conventional free layer  18 . Consequently, conventional MTJs  10  that utilize MgO as the conventional barrier layer  16  in combination with CoFeB as the conventional free layer  18  may be used in various device applications. 
     Although it may be possible to attain a high signal and low RA using the above-described conventional MTJ  10 , one of ordinary skill in the art will recognize that such a conventional MTJ  10  has other drawbacks. In particular, the free layer  18  of such a conventional MTJ  10  utilizes an amorphous magnetic layer of CoFeB, with B between zero and thirty atomic percent. However, amorphous layers of CoFeB exhibit a large magnetostriction. This magnetostriction results in poor soft magnetic performance of the conventional free layer  18 , making the conventional MTJ  10  unsuitable for use in HDD applications. 
     In order to address this issue, a conventional free layer  18  using a multilayer of CoFeB and NiFe has been implemented. The NiFe layer improves the soft magnetic performance of the conventional free layer  18 . However the use of such a multilayer for the conventional free layer  18  reduces signal achievable by a significant amount. In particular, an anneal at a temperature of approximately at least three hundred degrees Celsius is generally performed to orient the CoFeB layer to a ( 100 ) direction and, therefore, obtain a high magnetoresistance. However, an anneal at these temperatures causes growth of the CoFeB layer in an fcc ( 111 ) orientation because of the ( 111 ) preference of the NiFe layer. This change in orientation of the CoFeB layer results in a lower magnetoresistance. This low magnetoresistance is a disadvantage that reduces the applicability of such conventional MTJs  10  into ultra-high density HDD applications. 
     Accordingly, what is needed is a system and method for providing a magnetic element that may be utilized in high density HDD and/or other applications. The system and method address such a need. 
     BRIEF SUMMARY OF THE INVENTION 
     A method and system for providing a magnetic element are disclosed. The method and system comprise providing a pinned layer, a barrier layer, and a free layer. The free layer includes a first ferromagnetic layer, a second ferromagnetic layer, and an intermediate layer between the first ferromagnetic layer and the second ferromagnetic layer. The barrier layer includes MgO and resides between the pinned layer and the free layer. The first ferromagnetic layer resides between the barrier layer and the intermediate layer. The first ferromagnetic layer includes at least one of CoFeX and CoNiFeX, with X being selected from the group of B, P, Si, Nb, Zr, Hf, Ta, Ti, and being greater than zero atomic percent and not more than thirty atomic percent. The first ferromagnetic layer is ferromagnetically coupled with the second ferromagnetic layer. The intermediate layer is configured such that the first ferromagnetic layer has a first crystalline orientation and the second ferromagnetic layer has a second crystalline orientation different from the first ferromagnetic layer. 
     According to the method and system disclosed herein, magnetic elements that may have a high magnetoresistance in combination with a low RA may be provided. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a diagram of a conventional magnetic element, a magnetic tunneling junction. 
         FIG. 2  is a diagram of an exemplary embodiment of a magnetic element having an engineered free layer. 
         FIG. 3  is a diagram of another exemplary embodiment of a magnetic element having an engineered free layer. 
         FIG. 4  is a diagram of another exemplary embodiment of a magnetic element having an engineered free layer. 
         FIG. 5  is a diagram of another exemplary embodiment of a magnetic element having an engineered free layer. 
         FIG. 6  is a flow chart depicting one exemplary embodiment of a method for providing one embodiment of a magnetic element having an engineered free layer. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to magnetic elements. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiments and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the method and system are not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein. 
     A method and system for providing a magnetic element are disclosed. The method and system comprise providing a pinned layer, a barrier layer, and a free layer. The free layer includes a first ferromagnetic layer, a second ferromagnetic layer, and an intermediate layer between the first ferromagnetic layer and the second ferromagnetic layer. The barrier layer includes MgO and resides between the pinned layer and the free layer. The first ferromagnetic layer resides between the barrier layer and the intermediate layer. The first ferromagnetic layer includes at least one of CoFeX and CoNiFeX, with X being selected from the group of B, P, Si, Nb, Zr, Hf, Ta, Ti, and being greater than zero atomic percent and not more than thirty atomic percent. The first ferromagnetic layer is ferromagnetically coupled with the second ferromagnetic layer. The intermediate layer is configured such that the first ferromagnetic layer has a first crystalline orientation and the second ferromagnetic layer has a second crystalline orientation different from the first ferromagnetic layer. 
     The method and system will be described in terms of a particular magnetic element having certain components. However, one of ordinary skill in the art will readily recognize that this method and system will operate effectively for other magnetic memory elements having different and/or additional components not inconsistent with the method and system. One of ordinary skill in the art will also readily recognize that the method and system are described in the context of a structure having a particular relationship to the substrate. However, one of ordinary skill in the art will readily recognize that the method and system are consistent with other structures having different relationships to the substrate, such as components being ordered differently with respect to the substrate. For example, although certain embodiments are described in the context of bottom (pinned layer at the bottom) structures, one of ordinary skill in the art will readily recognize that the method and system are consistent with top (pinned layer at top) structures. In addition, the method and system are described in the context of certain layers being synthetic and/or simple. However, one of ordinary skill in the art will readily recognize that the layers could have another structure. Furthermore, the method and system are described in the context of magnetic elements having particular layers. However, one of ordinary skill in the art will readily recognize that magnetic elements having additional and/or different layers not inconsistent with the method and system could also be used. Moreover, certain components are described as being ferromagnetic. However, as used herein, the term ferromagnetic could include ferrimagnetic or like structures. Thus, as used herein, the term “ferromagnetic” includes, but is not limited to ferromagnets and ferrimagnets. The method and system are also described in the context of single elements. However, one of ordinary skill in the art will readily recognize that the method and system are consistent with the use of magnetic memories having multiple elements, bit lines, and word lines. 
       FIG. 2  is a diagram of one exemplary embodiment of a magnetic element  100  having an engineered free layer. The magnetic element  100  is a MTJ  100 . The MTJ  100  includes a pinned layer  110 , a barrier layer  120 , and a free layer  130 . The MTJ  100  also preferably may include seed layer(s)  102 , pinning layer  104 , capping layer(s)  106  and is formed on a substrate  101 . For example, the seed layer(s)  102  may include a bilayer of TaN and NiFeCr (on the TaN) or a bilayer of Ta and NiFeCr (on the Ta). The capping layer(s)  106  may include a bilayer of Ru and Ta (on the Ru) or a trilayer of Ru, Cu (on the Ru), and Ta (on the Cu). 
     The pinning layer  104  is preferably an antiferromagnetic (AFM) layer, for example including PtMn and/or IrMn. The pinning layer  104  is used to pin the magnetization  112  of the pinned layer  110  in a desired direction. However, in another embodiment, another mechanism might be used for pinning the magnetization  112  in the desired direction. 
     The pinned layer  110  preferably includes at least one of Co, Ni, and Fe. The pinned layer  110  has its magnetization  112  pinned in the desired direction, which may, for example, be along or perpendicular to the easy axis of the free layer  130 . The pinned layer  110  is shown as a simple layer. However, the pinned layer  110  may be a multilayer. For example, the pinned layer  110  may be an SAF layer including two ferromagnetic layers separated by a thin non-magnetic conductive layer, such as Ru. The ferromagnetic layers for such an SAF would preferably have their magnetizations aligned antiparallel. 
     The barrier layer  120  is nonmagnetic and insulating. The barrier layer  120  is thin, allowing tunneling of charge carriers through the barrier layer  120  when a current is driven through the MTJ  100  in a current-perpendicular-to-plane (CPP) configuration (in the z-direction in  FIG. 2 ). Consequently, current carriers may tunnel through the barrier layer  120 . In a preferred embodiment, the material(s) used for the barrier layer  120  includes MgO. In such an embodiment, the MgO is preferably crystalline, cubic in structure, and has ( 100 ) orientation. As a result, the MTJ  100  may have a high magnetoresistance. 
     The free layer  130  includes ferromagnetic layers  132  and  136  separated by an intermediate layer  134 . In some embodiments, for example used in microwave generator applications, the magnetic element  100  may be configured such that the free layer  130  may have its magnetic state changed due to spin transfer. Consequently, the dimensions of the free layer  130  for such applications are preferably small, in the range of few hundred nanometers. The ferromagnetic layers  132  and  136  are ferromagnetically coupled, for example through RKKY, orange peel coupling, or pinholes. The ferromagnetic layer  132  is preferably CoFeX or CoFeNiX, where X is selected from the group of B, P, Si, Nb, Zr, Hf, Ta, Ti. In addition, X is from zero atomic percent to not more than thirty atomic percent. In a preferred embodiment, X is at least five atomic percent. Thus, the ferromagnetic layer  132  preferably uses amorphous materials that transform to crystal structures with desired texture after post heat treatment and recrystallization. Thus, the ferromagnetic layer  132  is preferably configured to have a higher magnetoresistance, particularly when used with an MgO barrier layer  120 . The ferromagnetic layer  136  preferably includes CoFeY or NiFe, where Y is selected from the group of B, P, Si, Nb, Zr, Hf, Ta, and Ti. In addition, Y is from zero atomic percent to not more than thirty atomic percent. In a preferred embodiment, Y is at least five atomic percent. 
     The intermediate layer  134  is nonmagnetic and configured such that the ferromagnetic layers  132  and  136  have different crystalline orientations. The intermediate layer  134  can be considered to be configured for texture reconstruction or as a separate layer around which the free layer  130  has different crystalline orientations. These different crystalline orientations are configured to maintain a high magnetoresistance (signal) while providing better soft magnetic performance. The intermediate layer  134  may thus act as an intermediate media that either stops texture epitaxial growth between different parts/layers  132  and  136  of the free layer  130  if the intermediate layer  134  is in a thin regime, or bridges the parts  132  and  136  of the free layer  130  having different crystalline orientations if the intermediate layer  134  is in a thicker regime. The intermediate layer  134  may include at least one of Ru, Ir, Rh, Hf, Zr, Ta, and Ti. In the thin regime, the intermediate layer  134  of Ru may have a thickness of less than ten Angstroms. In the thicker regime, the intermediate layer  134  of Ru may have a thickness of at least ten Angstroms, but not so thick that the ferromagnetic layers  132  and  136  are no longer ferromagnetically aligned. However, the intermediate layer  134  is preferably Ru having a thickness of at least one Angstrom and not more than five Angstroms. In a preferred embodiment, the orientation of the ferromagnetic layer  132  is ( 002 ), while the orientation of the ferromagnetic layer  136  is ( 111 ). Also in a preferred embodiment, the orientation of the intermediate layer  134  is hcp ( 002 ). Thus, the intermediate layer  134  may help to prevent crystalline propagation from the ferromagnetic layer  136  to the ferromagnetic layer  132  due to a post-deposition anneal, for example at temperatures at or above approximately three hundred degrees Celsius. In addition, the intermediate layer  134  preferably prevents atomic interdiffusion during such a post-deposition anneal. 
     Because the ferromagnetic layer  132  has a particular orientation, preferably includes CoFeX, as described above, and is used in conjunction with the barrier layer  120  that is preferably crystalline MgO, the MTJ  100  may have a large magnetoresistance. This large magnetoresistance is due to the large asymmetry of the spin dependent electronic band structures at barriers and electrodes. Furthermore, use of CoFeB provides an improved thermal stability due to the use of the B. The B may reduce or prevent interfacial interdiffusion of metal atoms at elevated temperatures. Consequently, the structural or electrical degradation of the MTJ  100  due to temperature disturbances and electrical stress may be reduced. Because of the use of the intermediate layer  134 , the free layer  130  may have improved soft magnetic properties. For example, NiFe may be used for the ferromagnetic layer  136  to improve the soft magnetic properties and reduce magnetostriction substantially without adversely affecting themagnetoresistance. 
     Thus, the MTJ  100  may have improved the sensitivity when used in applications such as a magnetic recording head or in a conventional (field-switched) magnetic memory. In addition, for spin transfer switching applications, the MTJ  100  may have a smaller spin transfer current switching distribution. Moreover, processing instabilities due to external or structural stresses may be removed. Consequently, the MTJ  100  may be more suitable for high density recording applications, both in reading and storing data. 
       FIG. 3  is a diagram of another exemplary embodiment of a magnetic element  200  having an engineered free layer. The magnetic element  200  is a dual MTJ  200 . The dual MTJ  200  includes a first pinned layer  210 , a first barrier layer  220 , a free layer  230 , a second barrier layer  240 , and a second pinned layer  250 . The dual MTJ  200  may thus be considered to incorporate the MTJ  100  (for example in layers  210 ,  220 , and  230  or  230 ,  240 , and  250 ), but have additional layers (for example layers  240  and  250  or  210  and  220 , respectively). The dual MTJ  200  also preferably may include seed layer(s)  202 , first pinning layer  204 , second pinning layer  260 , and capping layer(s)  270  and is formed on a substrate  201 . For example, the seed layer(s)  202  may include a bilayer of TaN and NiFeCr (on the TaN) or a bilayer of Ta and NiFeCr (on the Ta). The capping layer(s)  270  may include a bilayer of Ru and Ta (on the Ru) or a trilayer of Ru, Cu (on the Ru), and Ta (on the Cu). 
     The pinning layers  204  and  260  are preferably an AFM layers, for example including PtMn and/or IrMn. The pinning layer  204  and  260  are used to pin the magnetizations  212  and  252  of the pinned layers  210  and  250 , respectively, in a desired direction. However, in another embodiment, another mechanism might be used for pinning the magnetizations  212  and  252  in the desired direction. In a preferred embodiment for magnetic memory applications, the magnetizations  212  and  252  are preferably parallel. However, other orientations may be used. 
     The pinned layers  210  and  250  each preferably includes at least one of Co, Ni, and Fe. The pinned layers  210  and  250  each has its magnetization  212  and  252 , respectively, pinned in the desired direction(s). These direction(s) may, for example, be along or perpendicular to the easy axis of the free layer  230 . The pinned layers  210  and  250  are shown as simple layers. However, the pinned layer  210  and/or  250  may be a multilayer. For example, the pinned layer  210  and/or  250  may be an SAF layer including two ferromagnetic layers separated by a thin non-magnetic conductive layer, such as Ru. The ferromagnetic layers for such an SAF would preferably have their magnetizations aligned antiparallel. 
     The barrier layers  220  and  240  are nonmagnetic and insulating. The barrier layers  220  and  240  are each thin, allowing tunneling of charge carriers through the barrier layer  220  and  240  when a current is driven through the dual MTJ  200  in a current-perpendicular-to-plane (CPP) configuration (in the z-direction in  FIG. 3 ). Consequently, current carriers may tunnel through the barrier layer  220  and the barrier layer  240 . In a preferred embodiment, the material(s) used for the barrier layer  220  includes MgO. In such an embodiment, the MgO is preferably crystalline, cubic in structure, and has ( 100 ) orientation. The barrier layer  240  may thus be crystalline or amorphous. As a result, the dual MTJ  200  may have a high magnetoresistance. Also in a preferred embodiment, the barrier layer  240  includes either MgO or aluminum oxide. 
     The free layer  230  is analogous to the free layer  130  depicted in  FIG. 2 . Referring back to  FIG. 3 , the free layer  230  thus includes ferromagnetic layers  232  and  236  separated by an intermediate layer  234 . In some embodiments, the magnetic element  200  may be configured such that the free layer  230  may have its magnetic state changed due to spin transfer. Consequently, the dimensions of the free layer  230  for such applications are preferably small, in the range of few hundred nanometers. The ferromagnetic layers  232  and  236  are ferromagnetically coupled, for example through RKKY, orange peel coupling, or pinholes. The ferromagnetic layer  232  is preferably CoFeX or CoFeNiX, where X is selected from the group of B, P, Si, Nb, Zr, Hf, Ta, and Ti. In addition, X is from zero atomic percent to not more than thirty atomic percent. In a preferred embodiment, X is at least five atomic percent. Thus, the ferromagnetic layer  232  preferably uses amorphous materials that transform to crystal structures with desired texture after post heat treatment and recrystallization. Thus, the ferromagnetic layer  232  is preferably configured to have a higher magnetoresistance, particularly when used with an MgO barrier layer  220 . The ferromagnetic layer  236  preferably includes CoFeY or NiFe, where Y is selected from the group of B, P, Si, Nb, Zr, Hf, Ta, and Ti. In addition, Y is from zero atomic percent to not more than thirty atomic percent. In a preferred embodiment, Y is at least five atomic percent. 
     The intermediate layer  234  is nonmagnetic and configured such that the ferromagnetic layers  232  and  236  have different crystalline orientations. The intermediate layer  234  can be considered to be configured for texture reconstruction or as a separate layer around which the free layer  230  has different crystalline orientations. These different crystalline orientations are configured to maintain a high magnetoresistance (signal) while providing better soft magnetic performance. The intermediate layer  234  may thus act as an intermediate media that either stops texture epitaxial growth between different parts/layers  232  and  236  of the free layer  230  if the intermediate layer  234  is in a thin regime, or bridges the parts  232  and  236  of the free layer  230  having different crystalline orientations if the intermediate layer  234  is in a thicker regime. The intermediate layer  234  may include at least one of Ru, Ir, Rh, Hf, Zr, Ta, and Ti. However, the intermediate layer  234  is preferably Ru having a thickness of at least one Angstrom and not more than five Angstroms. In a preferred embodiment, the orientation of the ferromagnetic layer  232  is ( 002 ), while the orientation of the ferromagnetic layer  236  is ( 111 ). Also in a preferred embodiment, the orientation of the intermediate layer  234  is hcp ( 002 ). Thus, the intermediate layer  234  may help to prevent crystalline propagation from the ferromagnetic layer  236  to the ferromagnetic layer  232  due to a post-deposition anneal, for example at temperatures at or above approximately three hundred degrees Celsius. In addition, the intermediate layer  234  preferably prevents atomic interdiffusion during such a post-deposition anneal. 
     The dual MTJ  200  shares many of the benefits of the MTJ  100 . Thus, the MTJ  200  has improved magnetoresistance, thermal stability, resistance to electrical stresses, and soft magnetic properties. Moreover, an enhanced signal due to the presence of two pinned layers  210  and  250  may be achieved. Thus, the dual MTJ  200  may be suitable for HDD and field-switched magnetic memories. 
       FIG. 4  is a diagram of another exemplary embodiment of a magnetic element  200 ′ having an engineered free layer. The magnetic element  200 ′ is a hybrid structure termed herein a hybrid magnetic element  200 ′. The hybrid magnetic element  200 ′ includes a first pinned layer  210 ′, a barrier layer  220 ′, a free layer  230 ′, a spacer layer  240 ′ that is conductive, and a second pinned layer  250 ′. The hybrid magnetic element  200 ′ may thus be considered to incorporate the MTJ  100  (in layers  210 ′,  220 ′, and  230 ′), but have additional layers (layers  240 ′ and  250 ′). The hybrid magnetic element  200 ′ may also be considered to incorporate a spin valve (in layers  230 ′,  240 ′, and  250 ′). The hybrid magnetic element  200 ′ also preferably may include seed layer(s)  202 ′, first pinning layer  204 ′, second pinning layer  260 ′, and capping layer(s)  270 ′ and is formed on a substrate  201 ′. For example, the seed layer(s)  202 ′ may include a bilayer of TaN and NiFeCr (on the TaN) or a bilayer of Ta and NiFeCr (on the Ta). The capping layer(s)  270 ′ may include a bilayer of Ru and Ta (on the Ru) or a trilayer of Ru, Cu (on the Ru), and Ta (on the Cu). 
     The pinning layers  204 ′ and  260 ′ are preferably an AFM layers, for example including PtMn and/or IrMn. The pinning layers  204 ′ and  260 ′ are used to pin the magnetizations  212 ′ and  252 ′ of the pinned layers  210 ′ and  250 ′, respectively, in a desired direction. However, in another embodiment, another mechanism might be used for pinning the magnetizations  212 ′ and  252 ′. In a preferred embodiment for magnetic memory applications, the magnetizations  212 ′ and  252 ′ are preferably parallel. However, other orientations may be used. 
     The pinned layers  210 ′ and  250 ′ each preferably includes at least one of Co, Ni, and Fe. The pinned layers  210 ′ and  250 ′ each has its magnetization  212 ′ and  252 ′, respectively, pinned in the desired direction(s). These direction(s) may, for example, be along or perpendicular to the easy axis of the free layer  230 ′. The pinned layers  210 ′ and  250 ′ are shown as simple layers. However, the pinned layer  210 ′ and/or  250 ′ may be a multilayer. For example, the pinned layer  210 ′ and/or  250 ′ may be an SAF layer including two ferromagnetic layers separated by a thin non-magnetic conductive layer, such as Ru. The ferromagnetic layers for such an SAF would preferably have their magnetizations aligned antiparallel. 
     The barrier layer  220 ′ is nonmagnetic and insulating. The barrier layer  220 ′ is thin, allowing tunneling of charge carriers through the barrier layer  220 ′ when a current is driven through the dual MTJ  200 ′ in a current-perpendicular-to-plane (CPP) configuration (in the z-direction in  FIG. 4 ). Consequently, current carriers may tunnel through the barrier layer  220 ′. In a preferred embodiment, the material(s) used for the barrier layer  220 ′ includes MgO. In such an embodiment, the MgO is preferably crystalline, cubic in structure, and has ( 100 ) orientation. As a result, the hybrid magnetic element  200 ′ may have a high magnetoresistance. 
     The spacer layer  240 ′ is conductive. For example, the spacer layer  240 ′ may include Cu and/or Ru. Thus, the spacer layer  240 ′ may be a multilayer. As a result, the resistance of the spin valve portion (layers  230 ′,  240 ′, and  250 ′) of the hybrid magnetic element  200 ′ may have a low resistance, yet contribute to the magnetoresistance. 
     The free layer  230 ′ is analogous to the free layer  130  depicted in  FIG. 2  and the free layer  230  depicted in  FIG. 3 . Referring back to  FIG. 4 , the free layer  230 ′ thus includes ferromagnetic layers  232 ′ and  236 ′ separated by an intermediate layer  234 ′. In some embodiments, the magnetic element  200 ′ may be configured such that the free layer  230 ′ may have its magnetic state changed due to spin transfer. Consequently, the dimensions of the free layer  230 ′ for such applications are preferably small, in the range of few hundred nanometers. The ferromagnetic layers  232 ′ and  236 ′ are ferromagnetically coupled, for example through RKKY, orange peel coupling, or pinholes. The ferromagnetic layer  232 ′ is preferably CoFeX or CoFeNiX, where X is selected from the group of B, P, Si, Nb, Zr, Hf, Ta, and Ti. In addition, X is from zero atomic percent to not more than thirty atomic percent. In a preferred embodiment, X is at least five atomic percent. Thus, the ferromagnetic layer  232 ′ preferably uses amorphous materials that transform to crystal structures with desired texture after post heat treatment and recrystallization. Thus, the ferromagnetic layer  232 ′ is preferably configured to have a higher magnetoresistance, particularly when used with an MgO barrier layer  220 ′. The ferromagnetic layer  236 ′ preferably includes CoFeY or NiFe, where Y is selected from the group of B, P, Si, Nb, Zr, Hf, Ta, and Ti. In addition, Y is from zero atomic percent to not more than thirty atomic percent. In a preferred embodiment, Y is at least five atomic percent. 
     The intermediate layer  234 ′ is nonmagnetic and configured such that the ferromagnetic layers  232 ′ and  236 ′ have different crystalline orientations. The intermediate layer  234 ′ can be considered to be configured for texture reconstruction or as a separate layer around which the free layer  230 ′ has different crystalline orientations. These different crystalline orientations are configured to maintain a high magnetoresistance (signal) while providing better soft magnetic performance. The intermediate layer  234 ′ may thus act as an intermediate media that either stops texture epitaxial growth between different parts/layers  232 ′ and  236 ′ of the free layer  230 ′ if the intermediate layer  234 ′ is in a thin regime, or bridges the parts  232 ′ and  236 ′ of the free layer  230 ′ having different crystalline orientations if the intermediate layer  234 ′ is in a thicker regime. The intermediate layer  234 ′ may include at least one of Ru, Ir, Rh, Hf, Zr, Ta, and Ti. However, the intermediate layer  234 ′ is preferably Ru having a thickness of at least one Angstrom and not more than five Angstroms. In a preferred embodiment, the orientation of the ferromagnetic layer  232 ′ is ( 002 ), while the orientation of the ferromagnetic layer  236 ′ is ( 111 ). Also in a preferred embodiment, the orientation of the intermediate layer  234 ′ is hcp ( 002 ). Thus, the intermediate layer  234 ′ may help to prevent crystalline propagation from the ferromagnetic layer  236 ′ to the ferromagnetic layer  232 ′ due to a post-deposition anneal, for example at temperatures at or above approximately three hundred degrees Celsius. In addition, the intermediate layer  234 ′ preferably prevents atomic interdiffusion during such a post-deposition anneal. 
     The hybrid magnetic element  200 ′ shares many of the benefits of the MTJ  100  and the dual MTJ  200 . Thus, the hybrid magnetic element  200 ′ has improved magnetoresistance, thermal stability, resistance to electrical stresses, and soft magnetic properties. Moreover, an enhanced signal due to the presence of two pinned layers  210 ′ and  250 ′ may be achieved. 
       FIG. 5  is a diagram of another embodiment of a magnetic element  200 ″ in accordance with the present invention having an engineered free layer. The magnetic element  200 ″ is preferably a dual MTJ  200 ″. The dual MTJ  200 ″ includes a first pinned layer  210 ″, a first barrier layer  220 ″, a free layer  230 ″, a spacer layer that is preferably a second barrier layer  240 ″, and a second pinned layer  250 ″. The dual MTJ  200 ″ may thus be considered to incorporate the MTJ  100  (for example in layers  210 ″,  220 ″, and  230 ″ or  230 ″,  240 ″, and  250 ″), but have additional layers (for example layers  240 ″ and  250 ″ or  210 ″ and  220 ″, respectively). The dual MTJ  200 ″ also preferably may include seed layer(s)  202 ″, first pinning layer  204 ″, second pinning layer  260 ″, and capping layer(s)  270 ″ and is formed on a substrate  201 ″. For example, the seed layer(s)  202 ″ may include a bilayer of TaN and NiFeCr (on the TaN) or a bilayer of Ta and NiFeCr (on the Ta). The capping layer(s)  270 ″ may include a bilayer of Ru and Ta (on the Ru) or a trilayer of Ru, Cu (on the Ru), and Ta (on the Cu). 
     The pinning layers  204 ″ and  260 ″ are preferably an AFM layers, for example including PtMn and/or IrMn. The pinning layer  204 ″ and  260 ″ are used to pin the magnetizations  212 ″ and  252 ″ of the pinned layers  210 ″ and  250 ″, respectively, in a desired direction. However, in another embodiment, another mechanism might be used for pinning the magnetizations  212 ″ and  252 ″ in the desired direction. In a preferred embodiment for magnetic memory applications, the magnetizations  212 ″ and  252 ″ are preferably parallel. However, other orientations may be used. 
     The pinned layers  210 ″ and  250 ″ each preferably includes at least one of Co, Ni, and Fe. The pinned layers  210 ″ and  250 ″ each has its magnetization  212 ″ and  252 ″, respectively, pinned in the desired direction(s). These direction(s) may, for example, be along or perpendicular to the easy axis of the free layer  230 ″. The pinned layers  210 ″ and  250 ″ are shown as simple layers. However, the pinned layer  210 ″ and/or  250 ″ may be a multilayer. For example, the pinned layer  210 ″ and/or  250 ″ may be an SAF layer including two ferromagnetic layers separated by a thin non-magnetic conductive layer, such as Ru. The ferromagnetic layers for such an SAF would preferably have their magnetizations aligned antiparallel. 
     The barrier layers  220 ″ and  240 ″ are nonmagnetic and insulating. The barrier layers  220 ″ and  240 ″ are each thin, allowing tunneling of charge carriers through the barrier layer  220 ″ and  240 ″ when a current is driven through the dual MTJ  200 ″ in a current-perpendicular-to-plane (CPP) configuration (in the z-direction in  FIG. 5 ). Consequently, current carriers may tunnel through the barrier layer  220 ″ and the barrier layer  240 ″. In a preferred embodiment, the material(s) used for the barrier layer  220 ″ includes MgO. In such an embodiment, the MgO is preferably crystalline, cubic in structure, and has ( 100 ) orientation. The barrier layer  240 ″ may thus be crystalline or amorphous. As a result, the dual MTJ  200 ″ may have a high magnetoresistance. Also in a preferred embodiment, the barrier layer  240 ″ includes either MgO or aluminum oxide. 
     The free layer  230 ″ is analogous to the free layer  130  depicted in  FIG. 2  and to the free layers  230  and  230 ′ depicted in  FIGS. 3 and 4 , respectively. Referring back to  FIG. 5 , the free layer  230 ″ thus includes ferromagnetic layers  232 ″ and  236 ″ separated by an intermediate layer  234 ″. The free layer  230 ″ also includes, however, an additional intermediate layer  238  and an additional ferromagnetic layer  239 . In some embodiments, the magnetic element  200 ″ may be configured such that the free layer  230 ″ may have its magnetic state changed due to spin transfer. Consequently, the dimensions of the free layer  230 ″ for such applications are preferably small, in the range of few hundred nanometers. The ferromagnetic layers  232 ″ and  236 ″ are ferromagnetically coupled, for example through RKKY, orange peel coupling, or pinholes. Similarly, the ferromagnetic layers  239  and  236 ″ are ferromagnetically coupled. The ferromagnetic layer  232 ″ is preferably CoFeX or CoFeNiX, where X is selected from the group of B, P, Si, Nb, Zr, Hf, Ta, and Ti. In addition, X is from zero atomic percent to not more than thirty atomic percent. In a preferred embodiment, X is at least five atomic percent. Thus, the ferromagnetic layer  232 ″ preferably uses amorphous materials that transform to crystal structures with desired texture after post heat treatment and recrystallization. Thus, the ferromagnetic layer  232 ″ is preferably configured to have a higher magnetoresistance, particularly when used with an MgO barrier layer  220 ″. The ferromagnetic layer  236 ″ may include CoFeY or NiFe, where Y is selected from the group of B, P, Si, Nb, Zr, Hf, Ta, and Ti. In addition, Y is from zero atomic percent to not more than thirty atomic percent. In a preferred embodiment, Y is at least five atomic percent. In a preferred embodiment, the ferromagnetic layer  236 ″ is NiFe. The ferromagnetic layer  239  may include CoFeZ or CoFeNiZ, where Z is selected from the group of B, P, Si, Nb, Zr, Hf, Ta, and Ti. In addition, Z is from zero atomic percent to not more than thirty atomic percent. In a preferred embodiment, Z is at least five atomic percent. 
     The intermediate layers  234 ″ and  238  are nonmagnetic and configured such that the ferromagnetic layers  232 ″ and  236 ″ and the ferromagnetic layers  236 ″ and  239 , respectively, have different crystalline orientations. The intermediate layers  234 ″ and  238  can be considered to be configured for texture reconstruction or as separate layers around which the free layer  230 ″ has different crystalline orientations. These different crystalline orientations are configured to maintain a high magnetoresistance (signal) while providing better soft magnetic performance. The intermediate layer  234 ″ may thus act as an intermediate media that either stops texture epitaxial growth between different parts/layers  232 ″ and  236 ″ of the free layer  230 ″ if the intermediate layer  234 ″ is in a thin regime, or bridges the parts  232 ″ and  236 ″ of the free layer  230 ″ having different crystalline orientations if the intermediate layer  234 ″ is in a thicker regime. The same holds true of the intermediate layer  238 . The intermediate layers  234 ″ and  238  each may include at least one of Ru, Ir, Rh, Hf, Zr, Ta, and Ti. However, the intermediate layers  234 ″ and  238  are each preferably Ru having a thickness of at least one Angstrom and not more than five Angstroms. In a preferred embodiment, the orientation of the ferromagnetic layers  232 ″ and  239  is ( 002 ), while the orientation of the ferromagnetic layer  236 ″ is ( 111 ). Also in a preferred embodiment, the orientation of each of the intermediate layers  234 ″ and  238  is hcp ( 002 ). Thus, the intermediate layers  234 ″ and  238  may help to prevent crystalline propagation from the ferromagnetic layer  236 ″ to the ferromagnetic layer  232 ″ and from the ferromagnetic layer  239  to the ferromagnetic layer  236 ″ due to a post-deposition anneal, for example at temperatures at or above approximately three hundred degrees Celsius. In addition, the intermediate layers  234 ″ and  238  preferably prevents atomic interdiffusion during such a post-deposition anneal. 
     The dual MTJ  200 ″ shares many of the benefits of the MTJ  100 . Thus, the MTJ  200 ″ has improved magnetoresistance, thermal stability, resistance to electrical stresses, and soft magnetic properties. Moreover, an enhanced signal due to the presence of two pinned layers  210 ″ and  250 ″ may be achieved. Thus, the dual MTJ  200 ″ may be suitable for HDD and field-switched magnetic memories. 
       FIG. 6  is a flow chart depicting one exemplary embodiment of a method  300  for providing one embodiment of a magnetic element having an engineered free layer. The method  300  is described primarily in the context of the MTJ  100 . However, one of ordinary skill in the art will readily recognize that the method  300  could also be used in providing other magnetic elements not inconsistent with the present invention. For clarity, steps may be omitted. In addition, one of ordinary skill in the art will readily recognize that certain steps may be combined or performed separately. For example, the method  300  is described in the context of providing layers of the magnetic element. In some embodiments, some or all of the layers of the magnetic element may be deposited and then the magnetic element is defined, typically by masking the layers and removing the exposed portions of the layers. Thus, formation of the magnetic element (and thus it individual layers) may not be considered completed until the magnetic element is defined. However, for clarity, the components of the magnetic element are described as being provided in a particular order. Similarly, although the steps of the method  300  are described in a particular order, at least some steps may be carried out in a different order in certain embodiments. 
     The method  300  preferably commences after the seed layer(s)  102 , if any, have been provided. The pinning layer  104 , which is preferably an AFM layer, is preferably provided, via step  302 . The pinned layer  110  is provided on the AFM layer  104 , via step  304 . Step  304  preferably includes providing the desired materials for the pinned layer  110  and orienting the magnetization  112  of the pinned layer  110  in the desired direction. The barrier layer  120  is provided, via step  306 . Step  306  preferably includes providing a crystalline MgO barrier layer  120  or an amorphous MgO barrier layer that is later transformed into crystalline through annealing. 
     The ferromagnetic layer  132  is provided, via step  308 . Step  308  preferably includes providing the layer  132  of CoFeX and/or CoNiFeX, with X being selected from the group of B, P, Si, Nb, Zr, Hf, Ta, and Ti, and being from zero atomic percent to not more than thirty atomic percent. In a preferred embodiment, step  308  includes providing a ferromagnetic layer with an X of at least five atomic percent. The intermediate layer  134  is provided, via step  310 . Thus, a nonmagnetic layer that may include at least one of Ru, Ir, Rh, Hf, Zr, Ta, and Ti is provided. In a preferred embodiment, step  310  provides an intermediate layer  134  that is composed of Ru, at least one Angstrom in thickness and not more than five Angstroms in thickness. The ferromagnetic layer  136  is provided, via step  312 . In a preferred embodiment, step  312  includes forming the ferromagnetic layer  136  of CoFeX or NiFe. The remainder of the magnetic element is fabricated, via step  314 . In one embodiment, for the magnetic element  100 , step  314  may include providing capping layer(s)  106 , as well as other steps. In another embodiment, for the dual MTJ  200 , step  314  may include providing an additional barrier layer  240 , providing a second pinned layer  250 , providing a second pinning layer  260 , and providing the capping layer(s)  270 . Similarly, for the hybrid magnetic element  200 ′, step  314  may include providing a conductive spacer layer  240 ′, providing a second pinned layer  250 ′, providing a second pinning layer  260 ′, and providing the capping layer(s)  270 ′. Moreover, additional steps, such as trimming or lapping of the structure, as well as formation of surrounding structures, may be performed. 
     Thus, using the method  300 , the magnetic element  100 ,  200 , and/or  200 ′ may be fabricated. Consequently, the benefits of these magnetic elements  100 ,  200 , and/or  200 ′ may be achieved. Furthermore, the method  300  and materials are described above is available and producible using conventional equipment resources for thin film manufacturing at ambient temperature. Consequently, degradation of the structure  100 ,  200 ,  200 ′ during a higher temperature anneal may be reduced or avoided. 
     A method and system for providing and using a magnetic element has been disclosed. The method and system have been described in accordance with the embodiments shown, and one of ordinary skill in the art will readily recognize that there could be variations to the embodiments, and any variations would be within the spirit and scope of the method and system. Accordingly, many modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims.