CN103544985A - Method and system for providing magnetic tunneling junctions usable in spin transfer torque magnetic memories - Google Patents

Abstract

Methods and systems for providing magnetic tunnel junctions usable in magnetic memories are disclosed. The method and system provide a magnetic junction. Free layers, symmetry filters, and pinned layers are provided. The free layer has a magnetic moment that can be switched between stable states when a write current flows through the magnetic junction. A symmetry filter transmits charge carriers of a first symmetry with a higher probability than charge carriers of another symmetry. Symmetry filters are located between the free layer and the pinned layer. The free layer and/or the pinned layer lie in a plane with charge carriers of the first symmetry at the Fermi level in the spin channel and not at the Fermi level in the other spin channel The charge carriers of the first symmetry of , and have a nonzero magnetic moment component perpendicular to the plane. The free layer and/or the pinned layer have at least one lattice mismatch with the symmetry filter of less than seven percent.

Description

Method and system for providing a magnetic tunnel junction usable in magnetic memory

Background technique

Magnetic memories, especially Magnetic Random Access Memory (MRAM), are attracting increasing interest due to their potential for high read/write speeds, endurance, non-volatility, and low power consumption during operation. One type of MRAM is spin-transfer torque random-access memory (STT-RAM). STT-RAM utilizes magnetic junctions that are at least partially written by driving a current through them.

Figure 1 shows a conventional magnetic tunnel junction (MTJ) 10, which can be used in a conventional STT-RAM. A conventional MTJ 10 is typically located on a bottom contact 11 , employing a conventional seed layer 12 , and under a top contact 16 . A conventional MTJ 10 includes a conventional antiferromagnetic (AFM) layer 20 , a conventional pinned layer 30 , a conventional tunneling barrier layer 40 and a conventional free layer 50 . A conventional cover layer 14 is also shown. The conventional free layer 50 has a changeable magnetic moment 52, while the magnetic moment 43 of the conventional pinned layer 30 is stable. More specifically, the magnetic moment 32 of the conventional pinned layer 30 is fixed by interaction with the conventional AFM layer 20 .

Conventional contacts 12 and 16 are used to drive current in a current-perpendicular-to-plane (CPP) direction or along the z-axis as shown in FIG. 1 . Current flowing through conventional pinned layer 30 becomes spin polarized and carries angular momentum. This angular momentum can be transferred to the conventional free layer 50 . If a sufficient amount of angular momentum is so transferred, the magnetic moment 52 of the free layer 50 can be converted to be parallel or antiparallel to the magnetic moment of the pinned layer 30 .

In order to improve the performance of STT-RAM, it is desirable to optimize various factors of the conventional magnetic junction 10 . For example, the conventional magnetic junction 10 can be designed for a desired critical current I _c for switching the thermally stable conventional free layer 50 . The critical current can be estimated by:

${\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}\frac{{<span\; class="notranslate">\; \&lang;</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; \&rang;</span>}_{\mathrm{<span\; class="notranslate">\; eff</span>}}}{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; K</span>}}}\mathrm{<span\; class="notranslate">\; 1.5</span>}\mathrm{<span\; class="notranslate">\; mA</span>}$

where <H> _eff is the average effective magnetic field seen by the precessing magnetic moment of the conventional free layer 50, _Hk is the magnetic field required to switch the magnetic moment 52 when applied along the easy axis, α is the damping constant, and η is Spin-torque efficiency, 1.5 mA represents current and fits a thermal stability coefficient (ΔE/k _B T ) of 60, where ΔE represents the energy barrier for thermal conversion, k _B is the Boltzmann constant, and T is the absolute temperature.

Conventional magnetic junctions 10 can be optimized to improve critical current. Designing a conventional magnetic junction 10 may include employing CoFe and/or CoFeB for the conventional pinned layer 30 and the conventional free layer 50 . CoFe and CoFeB tend to have in-plane magnetic moments, as shown by magnetic moments 32 and 52 . Furthermore, conventional tunnel junctions 40 are typically crystalline MgO. The combination of CoFe and CoFeB with MgO can lead to lower critical current.

Although the conventional magnetic tunnel junction 10 works, further improvements are desired. For example, magnetic junctions that can be used in magnetic memories that can be smaller, can be scaled to smaller sizes, employ low critical currents, can be easily fabricated, and/or have other properties are desired.

Therefore, an improved magnetic junction that can be used in higher density STT-RAM is desired.

Contents of the invention

Described are methods and systems for providing magnetic junctions. The method and system include providing a free layer, a symmetry filter and a pinned layer. The free layer has a first magnetic moment that is switchable between a plurality of stable magnetic states when a write current flows through the magnetic junction. A symmetry filter transmits charge carriers of a first symmetry with a higher probability than charge carriers of another symmetry. The pinned layer has a second magnetic moment pinned in a specific direction. Symmetry filters are located between the free layer and the pinned layer. At least one of the free layer and the pinned layer has charge carriers of the first symmetry at the Fermi level in the spin channel and no charge carriers at the Fermi level in the other spin channel Charge carriers of a first symmetry lie in a plane and have a non-zero magnetic moment component substantially perpendicular to the plane. The free layer and/or the pinned layer has at least one lattice mismatch of less than seven percent with the symmetric filter. In certain aspects, the symmetry filter includes at least one of Ge, GaAs, and ZnSe.

Description of drawings

Figure 1 shows a conventional magnetic tunnel junction.

Figure 2 shows an exemplary embodiment of a magnetic junction suitable for use in a magnetic memory.

Figure 3 shows an exemplary embodiment of the energy band structure for many-carrier and minority-carrier spin channels in the free layer and/or pinned layer of an exemplary embodiment of a magnetic junction.

Figure 4 illustrates an exemplary embodiment of transporting charge carriers through a symmetric filter based on wave function symmetry.

Fig. 5 shows another exemplary embodiment of a magnetic junction suitable for use in a magnetic memory, where both the free layer and the pinned layer have states with symmetry at energy meter energies, the symmetry preferentially Transmitted by the spin filter layer.

Figure 6 shows another exemplary embodiment of a magnetic junction suitable for use in a magnetic memory.

Figure 7 shows another exemplary embodiment of a magnetic junction suitable for use in a magnetic memory.

Figure 8 shows another exemplary embodiment of a magnetic junction suitable for use in a magnetic memory.

Figure 9 shows another exemplary embodiment of a magnetic junction suitable for use in a magnetic memory.

Figure 10 shows another exemplary embodiment of a magnetic junction suitable for use in a magnetic memory.

Figure 11 shows another exemplary embodiment of a dual magnetic junction suitable for use in magnetic memory.

Figure 12 shows an exemplary embodiment of a magnetic memory utilizing magnetic junctions.

Figure 13 shows an exemplary embodiment of a method for fabricating a magnetic tunnel junction suitable for use in a magnetic memory.

Detailed ways

Exemplary embodiments relate to magnetic junctions usable in magnetic devices, such as magnetic memories, and devices employing such magnetic junctions. The following description is given 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 exemplary embodiments, and the general principles and features described herein, will be readily apparent. The exemplary embodiments are described primarily in terms of particular methods and systems provided in particular implementations. However, the methods and systems will operate effectively in other implementations. Terms such as "exemplary embodiment," "one embodiment," and "another embodiment" can refer to the same or different embodiments and multiple embodiments. Embodiments will be described in relation to systems and/or devices having particular components. However, the system and/or device may include more or fewer components than shown, and changes may be made in the arrangement and type of these components without departing from the scope of the invention. Exemplary embodiments will also be described in the context of particular methods having certain steps. However, the methods and systems operate effectively with methods having different and/or additional steps and steps in a different order than the exemplary embodiments. Thus, the present invention is 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.

Methods and systems for providing magnetic junctions are described. The method and system include providing a free layer, a symmetry filter, and a pinned layer. The free layer has a first magnetic moment that is switchable between a plurality of stable magnetic states when a write current is passed through the magnetic junction. The symmetry filter transmits charge carriers with a first symmetry with a higher probability than charge carriers with other symmetries. The pinned layer has a second magnetic moment pinned in a specific direction. Symmetry filters are located between the free layer and the pinned layer. At least one of the free layer and the pinned layer has charge carriers of the first symmetry at the Fermi level in one spin channel and none at the Fermi level in the other spin channel The charge carriers of the first symmetry are in a plane and have a nonzero magnetic moment component substantially perpendicular to the plane. The free layer and/or the pinned layer have at least one lattice mismatch with the symmetry filter of less than seven percent. In certain aspects, the at least one lattice mismatch can be less than three or four percent. In certain aspects, the symmetry filter includes at least one of Ge, GaAs, and ZnSe.

Exemplary embodiments are described in the context of specific magnetic junctions and magnetic memories having certain compositions. Those of ordinary skill in the art will readily recognize that the present invention is consistent with the use of magnetic junctions and memories having other and/or additional components and/or other features not consistent with the present invention . The method and system are also described in the context of the current understanding of the spin transfer phenomenon. Accordingly, one of ordinary skill in the art will readily recognize that theoretical explanations of the performance of the methods and systems are based on this current understanding of spin transfer. Those of ordinary skill in the art will also readily recognize that the methods and systems are described in the context of structures having a particular relationship to a substrate. However, one of ordinary skill in the art will readily recognize that the methods and systems are consistent with other structures. Furthermore, the methods and systems 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 may have alternative structures. Furthermore, the methods and systems are described in the context of magnetic junctions with specific layers. However, one of ordinary skill in the art will readily recognize that magnetic junctions having additional and/or different layers inconsistent with the methods and systems may also be employed. Also, certain compositions are described as magnetic, ferromagnetic and ferrimagnetic. As used herein, the term magnetic may include ferromagnetic, ferrimagnetic or similar structures. Thus, as used herein, the terms "magnetic" or "ferromagnetic" include, but are not limited to, ferromagnets and ferrimagnets. The methods and systems are also described in the context of individual components. 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. Also, as used herein, "in-plane" is substantially in or parallel to the plane of one or more layers of the magnetic junction. Conversely, "vertical" corresponds to a direction substantially perpendicular to one or more layers of the magnetic junction.

FIG. 2 shows an exemplary embodiment of a magnetic junction 100 . For example, magnetic junction 100 may be used in magnetic memory where current is driven through magnetic junction 100 in the CPP direction. For clarity, FIG. 2 is not drawn to scale and certain portions of magnetic junction 100 may be omitted. The magnetic junction 100 includes a pinned layer 110 , a spin filter 120 and a free layer 130 . The magnetic junction 100 may also include other layers (not shown).

The free layer 130 is a magnetic layer with a changeable magnetic moment 131 . Magnetic moment 131 is shown with arrows at both ends to indicate that magnetic moment 131 can change direction. When a write current flows through the magnetic junction 100, the magnetic moment 131 can switch between stable magnetic states. Thus, in the exemplary embodiment shown in FIG. 2 , the spin transfer torque can be used to switch the magnetic moment 131 of the free layer 130 . For example, a current driven in the z-direction can convert the magnetic moment 131 to a magnetic moment 111 parallel or antiparallel to the pinned layer 110 . In some embodiments, free layer 130 has a thickness of at least one nanometer and no greater than ten nanometers. However, other thicknesses are possible. Although shown as a simple layer with a single magnetic moment 131, the free layer 130 may also include multiple ferromagnetic and/or nonmagnetic layers. For example, the free layer 130 may be a synthetic antiferromagnetic (SAF), comprising a magnetic layer antiferromagnetically coupled or ferromagnetically coupled through one or more thin layers such as Ru. Free layer 130 may also be an additional multilayer in which one or more sublayers are magnetic. Other structures for the free layer 130 may also be employed.

In the illustrated embodiment, free layer 130 has an easy axis along magnetic moment 131 . The magnetic moment 131 is stable along the easy axis. In the illustrated embodiment, the magnetic moment has an in-plane component. In other words, the magnetic moment 131 has a component substantially in the plane of the free layer 130 . Thus, in the illustrated embodiment, the magnetic moment 131 has a component parallel to the xy plane. In addition, the free layer magnetic moment 131 has a component substantially perpendicular to the plane. In other words, the free layer magnetic moment 131 has a component parallel to the z-axis of FIG. 2 . In some embodiments, magnetic moment 131 may be perpendicular to the plane. In such embodiments, the in-plane component of magnetic moment 131 is zero. In such an embodiment, the free layer 130 may include a material such as AlMn. In some of these embodiments, the free layer 130 may consist of AlMn in the L1 ₀ phase, with a (100) axis perpendicular to the plane. In other embodiments, the free layer 130 may include MnGa and/or MnIn.

The symmetry filter 120 is a layer that transmits charge carriers with a first symmetry with a higher probability than charge carriers with another symmetry. Transmission can be via tunneling. In some embodiments, the symmetry filter 120 only transmits charge carriers having a first symmetry with a higher probability. All other symmetries will have a lower probability of transmission. For example, the symmetry filter 120 may be crystalline MgO with a (100) texture. Such a layer transports current carriers with a wave function with _Δ1 symmetry in the (100) direction with a higher probability than current carriers with wave functions with other symmetries. Thus, the symmetry filter 120 may be considered to act similarly to a filter that passes current carriers having a first symmetry and excludes current carriers having other symmetries. In other embodiments, other materials may be used. For example, SrSnO ₃ can be used. Although an insulator used as a tunneling barrier is described for the symmetric filter 120, in other embodiments other materials with other electrical properties may be employed.

The pinned layer 110 has a magnetic moment 111 pinned in a specific direction. For example, magnetic moment 111 may be pinned by an AFM layer (not shown), a hard magnet (not shown), or via some other mechanism. The illustrated pinned layer 110 is a simple layer, consisting of a single magnetic layer. Although shown as a simple layer with a single magnetic moment 111, the pinned layer 110 may include multiple layers. For example, the pinned layer 110 may be a SAF including magnetic layers antiferromagnetically or ferromagnetically coupled through one or more thin layers such as Ru. The pinned layer 110 may also be an additional multilayer in which one or more sublayers are magnetic. Other structures for the pinned layer 110 may also be employed.

In the illustrated embodiment, the magnetic moment 111 is pinned such that it has an in-plane component. In other words, the magnetic moment 111 has a component substantially in the plane of the pinned layer 110 . Thus, in the illustrated embodiment, the magnetic moment 111 has a component parallel to the xy plane. In addition, the magnetic moment 111 has a component substantially perpendicular to the plane. In other words, the magnetic moment 111 has a component parallel to the z-axis of FIG. 2 . In some embodiments, magnetic moment 111 has a zero in-plane component. In such an embodiment, the pinned layer 110 may include a material such as AlMn. In some of these embodiments, the pinned layer 110 can be composed of AlMn in the L1 ₀ phase with a (100) orientation. In other embodiments, the pinned layer 100 may include MnGa.

Free layer 130 and/or pinned layer 110 are configured such that at least one of layers 110 and 130 has symmetric charge carriers transported by symmetry filter 120 in a spin channel at the Fermi level . In addition, at least one of the free layer 130 and the pinned layer 110 has no symmetric charge carriers at the Fermi level in the other spin channel. Such a free layer and/or pinned layer 110 also has its magnetization component 131/111 perpendicular to the plane. For example, free layer 130 and/or pinned layer 110 may have charge carriers with symmetry at the Fermi level in many spin channels, but not at the Fermi level in minority spin channels. There are symmetrical charge carriers at the stage. In ferromagnetic materials, many sub-spin channels have electrons whose spins are aligned with the direction of net magnetization. Minority spin channel electrons have their spins antiparallel to the many spin channel electrons. For a symmetry filter 120 that transports current carriers with _Δ1 symmetry, such as MgO with a (100) texture, layers 110 and/or 130 may have in a multisub-spin channel at the Fermi level The _Δ1 symmetry of the current carriers. However, minority spin channels either have current carriers without Δ1 symmetry or have current _carriers with _Δ1 symmetry spaced from the Fermi level. In some embodiments, layers 110 and/or 130 having these properties also have a magnetization perpendicular to the plane.

For example, it has been found that the free layer 130 and/or the pinned layer 110 comprising L1 ₀ phase and (100) oriented AlMn have a perpendicular magnetic moment and have a desired symmetry at the Fermi level. More specifically, if the pinned layer 110 includes AlMn of the L1 ₀ phase whose (100) axis is perpendicular to the plane, the pinned layer 110 will have a magnetic moment 111 perpendicular to the plane. Furthermore, the pinned layer 110 will have charge carriers with _Δ1 symmetry at the Fermi level in the multisub-spin channel. Charge carriers with _Δ1 symmetry for a multisub spin channel are therefore more likely to transport current through the pinned layer 110 . The pinned layer 110 having such a composition and structure has no charge carriers having _Δ1 symmetry in the (001) direction in the minority carrier channel. The band structure 160 of an exemplary embodiment of such a layer is shown in FIG. 3 . It should be noted, however, that the energy bands shown are for illustrative purposes only and are not intended to accurately reflect the energy band structure of such materials. As seen in the band structure, many sub-spin channels have charge carriers with _Δ1 symmetry at the Fermi level. Thus, the _Δ1 symmetry charge carriers are likely to carry current through the pinned layer 110 . Free layers 110 having the same crystal structure and composition may have similar properties. Similarly, the free layer 130 and/or the pinned layer 110 may comprise MnGa and have properties similar to those described above.

Such a pinned layer 110 and/or a free layer 130 can be used in combination with a spin filter 120 that has a high probability for transporting charge carriers with _Δ1 symmetry, while for transporting Charge carriers with wave functions with other symmetries have lower probability. Thus, while all wave functions for charge carriers are expected to decay in insulating spin filters, the _Δ1 wave function decays more slowly. From the perspective of transmission and reflection, charge carriers with _Δ1 symmetry are transported with higher probability than electrons with wave functions of other symmetries. Charge carriers that are not transported can be reflected. For example, MgO with a (100) orientation tends to transport electrons with wave functions of a particular _Δ1 symmetry with higher probability than electrons with wave functions of other symmetries. Figure 4 shows the relatively slow decay of the _Δ1 wave function in MgO compared to other symmetry cases. Because the multisub spin channel has a _Δ1 symmetry at the Fermi level, the multisub charge currents in the pinned layer 110 and the free layer 130 from the Fermi level are likely to be transported through the spin filter 120 . As a result, a high degree of spin polarization can be achieved. Therefore, the efficiency of spin torque induced transition can be improved and the critical current can be reduced. In this way, the magnetic junction 100 functions in a manner similar to conventional magnetic junctions 100 by employing _Δ1 electrons at the Fermi level in the many-carrier spin channel and not at the Fermi level in the minority-carrier spin channel. CoFe with Δ ₁ electrons at the energy level.

Furthermore, for materials such as AlMn, the magnetic moments 111/131 may be perpendicular to the plane. Therefore, for AlMn, the quantity <H> _eff /H _k is 1 or close to 1. This feature can also reduce the critical current. As a result, the performance of the magnetic junction 100 can be improved. Therefore, the magnetic junction 100 can be used in magnetic memory such as STT-RAM with improved performance. Other applications for magnetic junction 100 are also possible.

Additionally, the symmetry filter 120 may have additional properties relative to the pinned layer 110 and/or the free layer 130 . In certain embodiments, the lattice mismatch between one or both of layers 110 and 130 adjacent to symmetry filter 120 may desirably be low. For example, the lattice mismatch between layer 120 and layers 110 and/or 130 may be less than seven percent. In some embodiments, the lattice mismatch between layer 120 and layers 110 and/or 130 may be less than three or four percent. Lattice mismatch is the difference between the lattice positions for adjacent layers. Thus, the lattice mismatch depends on both the layer's lattice constant and the layer's texture. A smaller lattice mismatch can lead to an increased chance that magnetic layers 110 and/or 130 have the desired magnetic anisotropy. In certain embodiments, MgO(001) may have a lattice mismatch of at least seven percent with L1 ₀ AlMn. In some embodiments, this larger lattice mismatch results in different magnetic anisotropy for the pinned layer 110 and/or the free layer 130 . The magnetic anisotropy induced by this mismatch can result in an in-plane magnetic moment for the free layer 130 and/or the pinned layer 110 . In some embodiments, this is not desired. Furthermore, in some cases lattice mismatch can adversely affect the band structure. This would lead to a reduced polarization of the current carriers, which is undesirable. Therefore, it is desirable to reduce the lattice mismatch to achieve the desired magnetic anisotropy and/or spin polarization. For example, the free layer 130 and/or the pinned layer 110 may have high perpendicular magnetic anisotropy and a magnetic moment perpendicular to the plane. Similarly, the free layer 130 and/or the pinned layer 110 may have more electrons in multiple sub-spin channels and fewer (or no) electrons in other spin channels.

Reducing the lattice mismatch can be achieved in many ways. In some embodiments, the lattice of the symmetry filter 120 shrinks or expands to approximate the lattice of the pinned layer 110 and/or the free layer 130 . For example, the lattice constant of MgO employed in symmetry filter 120 may be greater than the lattice constant of the material employed in pinned layer 110 and/or free layer 130 (eg, AlMn L1 ₀ ). Therefore, the lattice of the symmetric filter layer 120 is expected to be shrunk. In some embodiments, this is achieved by using Ge, GaAs, ZnSe, or other symmetry filters that have a lower lattice constant than that of MgO in symmetry filter 120 . Therefore, the lattice constant of the symmetry filter 120 is close to that of AlMn L1 ₀ and/or other materials for the pinned layer 110/free layer 130 . The resulting lattice mismatch between the symmetric filter layer 120 and the pinned layer 110 and/or the free layer 130 may be less than seven percent. In certain embodiments, the lattice mismatch between symmetric filter layer 120 and layers 110 and/or 130 may be less than three or four percent. Accordingly, the crystal lattice of the material used for the symmetry layer 120 may be shrunk to be close to the crystal lattice of the pinned layer 110 and/or the free layer 130 . In other embodiments, the crystal lattice of the pinned layer 110 and/or the free layer 130 may be enlarged. In certain embodiments, this may be achieved by doping or other means that may increase the lattice constant of the AlMn or other material employed in layers 110 and/or 130 . In other embodiments, other materials may be used for layers 110 and/or 130 . For example, MnGa and/or MnIn may be used. However, it is desirable that the means for more closely matching the lattice do not unduly disturb the magnetic properties of layers 110 and 130 .

Figure 5 shows another exemplary embodiment of a magnetic junction 100' that may be used in a magnetic memory. For clarity, Figure 5 is not to scale. Magnetic junction 100' includes similar components to magnetic junction 100 shown in FIG. 2 . Accordingly, similar components are similarly labeled. Thus, the magnetic junction 100' includes a pinned layer 110', a symmetry filter 120', and a free layer 130', similar to the pinned layer 110, the symmetry filter 120, and the free layer 130, respectively. Also shown is a seed layer 102 , a pinning layer 104 and a capping layer 106 . In other embodiments, the seed layer 102, the pinning layer 104, and/or the capping layer 106 may be omitted. Additionally, contacts (not shown) may also be provided to drive current in the desired direction. The seed layer 102 can be used to provide a template for the desired crystal structure of the pinned layer 104 . The pinning layer 104 may include an AFM layer, a hard magnet, or other material for pinning the magnetization of the pinned layer 110&apos;.

In the illustrated embodiment, the magnetic moment 111' of the pinned layer 110' and the magnetic moment 131' of the free layer 130' are perpendicular to the plane. In addition, both the free layer 130' and the pinned layer 110' are configured such that each of the layers 110' and 130' has a higher value at the Fermi level in a first spin channel, such as a multi-sub-spin channel. Symmetrical charge carriers that are likely to be transported by the symmetry filter. In certain embodiments, at least one of the free layer 130' and the pinned layer 110' has no symmetric charge-carrying at the Fermi level in other spin channels (e.g., minority spin channels) son. For example, both the pinned layer 110 ′ and the free layer 130 ′ may include AlMn having an L1 ₀ crystal structure and a (100) axis perpendicular to the plane. Such materials have _Δ1 electrons at the Fermi level in many-carrier spin channels, but no _Δ1 electrons in the (100) direction in minority-carrier spin channels. In addition, MgO or SrSnO ₃ having a (100) texture may be used as the spin filter 120 ′. In some embodiments, the lattice mismatch between symmetric filter 120' and layers 110' and/or 130' is less than seven percent. In some embodiments, the lattice mismatch between symmetry filter 120' and layers 110' and/or 130' may be less than three or four percent. For example, the symmetry filter 120' may include Ge, GaAs, and or ZnSe. The pinned layer 110' and/or the free layer 130' may include MnGa and/or MnIn.

Magnetic junction 100 ′ shares the benefits of magnetic junction 100 . Since the magnetic moments 111' and 131' are perpendicular to the plane, the quantity <H> _eff / _Hk is unity. In addition, spin polarization efficiency can be improved. Therefore, the performance of the magnetic junction can be improved.

Figure 6 shows another exemplary embodiment of a magnetic junction 100" suitable for use in a magnetic memory. For clarity, Figure 6 is not to scale. The magnetic junction 100" includes similar components to the magnetic junctions 100/100' . Accordingly, similar components are similarly labeled. Thus, magnetic junction 100" includes pinned layer 110", symmetry filter 120", and free layer 130", similar to pinned layer 110/110', symmetry filter 120/120', and free layer 130, respectively. /130'. Also shown are a seed layer 102', a pinning layer 104' and a capping layer 106'. In other embodiments, the seed layer 102', the pinning layer 104' and/or the capping layer 106' may be omitted. The seed layer 102' can be used to provide a template for the desired crystal structure of the pinned layer 104'. The pinned layer 104' may include an AFM layer, a hard magnet, or other material for pinning the magnetization of the pinned layer 110". Additionally, contacts (not shown) may also be provided to drive current in a desired direction.

In the illustrated embodiment, the magnetic moment 131" of the free layer 130" is perpendicular to the plane. In addition, the free layer 130" is configured such that the layer and 130' have symmetric electrical properties that are transported by the symmetry filter 120" with high probability at the Fermi level in a spin channel such as a multisub-spin channel. Charge carriers. In some embodiments, the free layer 130" has no symmetric charge carriers at the Fermi level in other spin channels, such as minority spin channels. For example, the free layer 130 ″ may include AlMn having a L1 ₀ crystal structure and a (100) axis perpendicular to the plane. In addition, MgO or SrSnO ₃ having a (100) texture may be used as the spin filter 120 ″. The pinned layer 110" may include other magnetic materials. For example, the pinned layer 110" includes bcc(001)Fe, bcc(001)Co, and/or bcc(001)FeCo. In some embodiments, the pinned layer 110" may also have its magnetization perpendicular to the plane (not shown in FIG. 6). However, other orientations are possible. In some embodiments, symmetry filtering The lattice mismatch between device 120" and layers 110" and/or 130" is less than seven percent. In some embodiments, the lattice mismatch between symmetric filter layer 120" and layers 110" and/or 130" may be less than three or four percent. For example, symmetric filter 120" Ge, GaAs and/or ZnSe may be included. The pinned layer 110" and/or the free layer 130" may include MnGa and/or MnIn.

The magnetic junction 100" shares the benefits of the magnetic junction 100/100'. Since the magnetic moment 131' is perpendicular to the plane, the quantity <H> _eff / _Hk is unity. In addition, the spin polarization efficiency can be improved. Therefore, the magnetic Knot 100" performance.

FIG. 7 shows another embodiment of a magnetic junction 100'' suitable for use in a magnetic memory. For clarity, Figure 7 is not to scale. Magnetic junction 100''' includes similar components to magnetic junction 100/100'/100". Accordingly, similar components are similarly labeled. Thus, magnetic junction 100''' includes pinned layer 110''', symmetric Symmetrical filter 120''' and free layer 130''', similar to pinned layer 110/110'/110", symmetrical filter 120/120'120" and free layer 130/130'/130" . Also shown are the seed layer 102", the pinning layer 104", and the covering layer 106". In other embodiments, the seed layer 102", the pinning layer 104", and/or the covering layer 106" may be omitted. The seed layer 102" can be used to provide a template for the desired crystal structure of the pinned layer 104". The pinning layer 104''' may include an AFM layer, a hard magnet, or other materials for pinning the magnetization of the pinned layer 100'''. Additionally, contacts (not shown) may also be provided to drive current in the desired direction.

In the illustrated embodiment, the magnetic moment 111'' of the pinned layer 110''' is perpendicular to the plane. In addition, the pinned layer 110''' is configured such that the pinned layer 110''' has an electrical symmetry in the multi-sub-spin channel that is transmitted by the symmetry filter 120''' at the Fermi level. load streamer. In some embodiments, the pinned layer 110'' has no symmetric charge carriers at the Fermi level in the minority spin channel. For example, the pinned layer 110 ″ may include AlMn having an L1 ₀ crystal structure and a (100) axis perpendicular to a plane. In addition, MgO or SrSnO ₃ with (100) texture can be used as the spin filter 120'''. The free layer 130''' may include other magnetic materials. For example, the free layer 130 ″ includes bcc(001) Fe, bcc(001) Co, and/or bcc(001) FeCo. In the illustrated embodiment, the free layer 130''' has its magnetization 131''' perpendicular to the plane. However, other orientations are possible. In certain embodiments, the lattice mismatch between symmetry filter 120''' and layers 110''' and/or 130''' is less than seven percent. In some embodiments, the lattice mismatch between symmetry filter 120''' and layers 110''' and/or 130''' may be less than three or four percent. For example, the symmetry filter 120''' may include Ge, GaAs and/or ZnSe. The pinned layer 110''' and/or the free layer 130''' may include MnGa and/or MnIn.

Magnetic junction 100''' shares the benefits of magnetic junctions 100/100'/100''. Since the magnetic moment 111'' is perpendicular to the plane, the quantity <H> _eff / _Hk is unity. In addition, spin polarization efficiency can be improved. Therefore, the performance of the magnetic junction 100''' may be improved.

FIG. 8 shows another exemplary embodiment of a magnetic junction 200 suitable for use in a magnetic memory. For clarity, Figure 8 is not to scale. Magnetic junction 200 includes similar components to magnetic junction 100/100' shown in FIGS. 2 and 5 . Accordingly, similar components are similarly labeled. Thus, magnetic junction 200 includes pinned layer 210, symmetry filter 220, and free layer 230, similar to pinned layer 110/110', symmetry filter 120/120', and free layer 130/130', respectively. Also shown are a seed layer 202, a pinning layer 204, and a cover layer 206, similar to the seed layer 102, pinning layer 104, and cover layer 106, respectively. In other embodiments, the seed layer 202, the pinning layer 204, and/or the capping layer 206 may be omitted. Additionally, contacts (not shown) may also be provided to drive current in the desired direction.

In the illustrated embodiment, the pinned layer 210 and the free layer 230 are SAF. Accordingly, pinned layer 210 includes ferromagnetic layers 212 and 216 separated by nonmagnetic spacer layer 214 . Similarly, free layer 230 includes ferromagnetic layers 232 and 236 separated by nonmagnetic spacer layer 234 . Spacer layers 214 and 234 are typically Ru. In the illustrated embodiment, the magnetic moments 211 and 215 of the pinned layer 210 and the magnetic moments 231 and 235 of the free layer 230 are perpendicular to the plane. Furthermore, both the free layer 130' and the pinned layer 110' are configured such that each of the layers 210 and 230 in a spin channel, such as a multi-sub-spin channel, is transported by the symmetry filter 220 at the Fermi level. symmetrical charge carriers. In certain embodiments, at least one of the free layer 230 and the pinned layer 210 has no symmetric charge carriers at the Fermi level in other spin channels, such as minority carrier spin channels. For example, both the ferromagnetic layers 212 and 216 of the pinned layer 210 and the ferromagnetic layers 232 and 236 of the free layer 230 may include AlMn having an L1 ₀ crystal structure and a (100) axis perpendicular to the plane. However, for such an embodiment, spacer layers 214 and 234 can allow antiferromagnetic coupling between ferromagnetic layers 212 and 216 and between layers 232 and 236 . Additionally, spacer layers 214 and 234 will provide a suitable growth template for the desired crystal structure and texture of layers 216 and 236 . In addition, MgO or SrSnO ₃ having a (100) texture may be used as the spin filter 220 . In certain embodiments, the lattice mismatch between symmetry filter 220 and layers 216 and/or 232 is less than seven percent. In certain embodiments, the lattice mismatch between symmetry filter 220 and layers 216 and/or 232 may be less than three or four percent. For example, symmetry filter 220 may include Ge, GaAs, and/or ZnSe. Layer 232 and/or layer 216 may include MnGa and/or MnIn.

Figure 9 shows another exemplary embodiment of a magnetic junction 200' suitable for use in a magnetic memory. For clarity, Figure 9 is not to scale. Magnetic junction 200' includes similar components to magnetic junction 100/100'/200. Accordingly, similar components are similarly labeled. Thus, the magnetic junction 200' comprises a pinned layer 210', a symmetry filter 220' and a free layer 230' similar to layers 210/110/110', 220/120/120' and 230/130/130', respectively. . Also shown are a seed layer 202', a pinning layer 204', and a capping layer 206'. In other embodiments, the seed layer 202', the pinning layer 204', and/or the capping layer 206' may be omitted. The seed layer 202' can be used to provide a template for the desired crystal structure of the pinned layer 204'. The pinning layer 204' may include an AFM layer, a hard magnet, or other material for pinning the magnetization of the pinned layer 210''. Additionally, contacts (not shown) may also be provided to drive current in the desired direction.

In the illustrated embodiment, the free layer 230 ′ is a SAF comprising layers 232 ′, 234 ′, and 236 ′ similar to layers 232 , 234 , and 236 . In the illustrated embodiment, the magnetic moments 231 and 235 of the free layer 230' are perpendicular to the plane. In other embodiments, the magnetic moment of the pinned layer 210' is perpendicular to the plane. Furthermore, the free layer 230' is configured such that the layer 230' has symmetric charge carriers transported at the Fermi level by the symmetry filter 220' in a multisub-spin channel. In some embodiments, the free layer 230' has no symmetric charge carriers at the Fermi level in the minority spin channel. For example, the free layer 230 ′ may include AlMn having an L1 ₀ crystal structure and a (100) axis perpendicular to a plane. In addition, MgO or SrSnO ₃ having a (100) texture may be used as the spin filter 220 ′.

In the illustrated embodiment, the magnetic moments 231' and 235' of the free layer 230' are perpendicular to the plane. Furthermore, the free layer 230' is configured such that the layer 230' has, in a spin channel, symmetric charge carriers that are transported by the symmetry filter with high probability at the Fermi level. For example, a multisub-spin channel may include symmetric charge carriers at the Fermi level. In some embodiments, the free layer 230' is devoid of symmetric charge carriers that are transported with higher probability at the Fermi level in other spin channels, such as minority spin channels. For example, the free layer 130 ′ may include AlMn having an L1 ₀ crystal structure and a (100) axis perpendicular to a plane. In addition, MgO or SrSnO ₃ having a (100) texture may be used as the spin filter 220 ′. The pinned layer 210' may include other magnetic materials. For example, the pinned layer 210 ′ includes bcc(001)Fe, bcc(001)Co, and/or bcc(001)FeCo. Although the magnetic moment 211' of the pinned layer is shown perpendicular to the plane, other orientations are possible. In certain embodiments, the lattice mismatch between symmetry filter 220' and layers 210' and/or 232' is less than seven percent. In some embodiments, the lattice mismatch between symmetry filter 220' and layers 210' and/or 232' may be less than three or four percent. For example, the symmetry filter 220' may include Ge, GaAs and/or AnSe. Layer 232' and/or layer 210' may include MnGa and/or MnIn.

FIG. 10 shows another exemplary embodiment of a magnetic junction 200″ suitable for use in a magnetic memory. For clarity, FIG. 10 is not to scale. Magnetic junction 200″ includes magnetic junctions 100/100″/200/ 200' similar components. Accordingly, similar components are similarly labeled. Accordingly, magnetic junction 200" includes pinned layer 210", symmetry filter 220", and free layer 230", similar to layers 210/210', respectively /110/110', 220/220'/120/120' and 230/230'/130/130'. Seed layer 202", pinning layer 204", and cover layer 206" are also shown. In other embodiments, the seed layer 202", the pinning layer 204", and/or the capping layer 206" may be omitted. The seed layer 202" may provide a template for the desired crystal structure of the pinning layer 204". The pinning layer 204" AFM layers, hard magnets, or other materials for pinning the magnetization of the pinned layer 210" may be included. In addition, contacts (not shown) may also be provided to drive current in a desired direction.

In the illustrated embodiment, pinned layer 210" is a SAF and includes layers 212', 214', and 216' similar to layers 212, 214, and 216. In the illustrated embodiment, pinned layer 210 "The magnetic moments 211' and 215' are perpendicular to the plane. In other embodiments, the magnetic moment of the free layer 230" is perpendicular to the plane. In addition, the pinned layer 210" is configured such that the layer 210" has a Fermi energy in a spin channel (eg, a multi-sub-spin channel). Symmetrical charge carriers that are transported by the symmetry filter 220'' with a higher probability at the level. In some embodiments, the pinned layer 210" is in other spin channels (e.g., minority spin channels) There are no symmetric charge carriers at the Fermi level. For example, the pinned layer 210 ″ may include AlMn having a L1 ₀ crystal structure and a (100) axis perpendicular to the plane. In addition, MgO or SrSnO ₃ having a (100) texture may be used as the spin filter 220 ″.

In the illustrated embodiment, the magnetic moments 211 and 215 of the pinned layer 210" are perpendicular to the plane. Furthermore, the pinned layer 210" is configured such that the layer 210" is in a spin channel such as a multi-sub-spin channel Charge carriers with symmetry that are transported with higher probability at the Fermi level by the symmetry filter 220″. In some embodiments, the pinned layer 210″ is in other spin channels such as minority There are no symmetric charge carriers at the Fermi level in the spin channel. For example, the pinned layer 210 ″ may include AlMn having a L1 ₀ crystal structure and a (100) axis perpendicular to the plane. In addition, MgO or SrSnO ₃ having a (100) texture may be used as the spin filter 220 ″. The free layer 230" may include other magnetic materials. For example, the free layer 230" includes bcc(001)Fe, bcc(001)Co and/or bcc(001)FeCo. Although the magnetic moment 231" of the free layer is shown perpendicular to the plane, other orientations are possible. In some embodiments, the lattice between the symmetry filter 220" and the layers 216' and/or 230" The mismatch is less than seven percent. In some embodiments, the lattice mismatch between symmetric filter 220" and layers 216' and/or 230" may be less than three or four percent. For example , the symmetry filter 220" may include Ge, GaAs and/or ZnSe. Layer 230" and/or layer 216' may include MnGa and/or MnIn.

Magnetic junctions 200, 200' and 200" share the benefits of magnetic junctions 100/100'/100". Since the magnetic moments of layers 210/210'/210" and 230/230'/230" can be perpendicular to the plane, the quantity <H> _eff /H _k is unity. In addition, spin polarization efficiency can be improved. Therefore, the performance of the magnetic junctions 200, 200' and 200" may be improved.

FIG. 11 shows another exemplary embodiment of a magnetic junction 300 suitable for use in a magnetic memory. For clarity, Figure 11 is not to scale. Magnetic junction 300 includes similar components to magnetic junctions 100/100&apos;/100&quot;/200/200&apos;/200&quot; shown in Figures 2 and 5-10. Accordingly, similar ingredients are similarly labeled. Thus, the magnetic junction 300 includes a pinned layer 310, a symmetry filter 320, and a free layer 330 similar to the pinned layer 110/110'/210, the symmetry filter 120/120'/220, and the free layer 130, respectively. /130'/230. Also shown is a seed layer 302, a pinning layer 304, and a cover layer 306, similar to the seed layer 102/102'/102"/202/202'/202", pinning layer 104/104'/104"/204, respectively. /204'/204"204''' and overlay 106/106'/106"/206/206'/206". In other embodiments, the seed layer 302, the pinning layer 304, and/or the capping layer 306 may be omitted. The magnetic junction 300 also includes an additional spacer layer 340 , an additional pinned layer 350 and an additional pinned layer 360 . Thus, magnetic junction 300 may be considered to include a magnetic element similar to magnetic element 100/100'/100"/200/200'/200" plus additional layers 340, 350, and 360.

In the illustrated embodiment, the further spacer layer 340 may be a tunneling barrier layer. In other embodiments, the additional spacer layer 340 may be conductive. Additionally, in some embodiments, the additional spacer layer 340 may be a symmetric filter, such as the MgO described above. Additional pinned layers 350 may be similar to layers 110/110'/110"/110'"/210/210'/210". Accordingly, the pinned layer 350 may have symmetric charge carriers transported by the symmetry filter 320 with a higher probability at the Fermi level in a spin channel such as a multisub-spin channel. In certain embodiments, the additional pinned layer 350 has no symmetric charge carriers at the Fermi level in another spin channel, such as a minority spin channel. For example, both pinned layers 350 may include AlMn having an L1 ₀ crystal structure and a (100) axis perpendicular to the plane. The magnetic moment 351 of the additional pinned layer may thus be perpendicular to the plane. It should be noted that although magnetic moments 311 and 351 are shown as antiparallel, other configurations may be employed. In addition, MgO or SrSnO ₃ having a (100) texture may be used so that the spacer layer 340 functions as a spin filter. Furthermore, while shown as simple layers, one or more of layers 310, 330, and 350 may be SAFs. In some embodiments, the lattice mismatch between symmetry filter 320 and layers 330 and/or 310 is less than seven percent. In some embodiments, the lattice mismatch between symmetry filter 320 and layers 330 and/or 310 may be less than three or four percent. For example, symmetry filter 320 may include Ge, GaAs, and/or ZnSe. Layer 330 and/or layer 310 may include MnGa and/or MnIn. Similarly, if layer 340 is a symmetric filter, the lattice mismatch between symmetric filter 340 and layers 330 and/or 360 is less than seven percent. In some embodiments, the lattice mismatch between symmetry filter 340 and layers 330 and/or 360 may be less than three or four percent. For example, symmetry filter 340 may include Ge, GaAs, and/or ZnSe. Layer 330 and/or layer 360 may include MnGa and/or MnIn.

Dual magnetic junctions 300 share the benefits of magnetic junctions 100/100'/100"/200/200'/200". Since the magnetic moments of layers 210/210'/210"/310, 230, 230'/230"/330 and optionally 350 may be perpendicular to the plane, the quantity <H> _eff /H _k is unity. In addition, spin polarization efficiency can be improved. Therefore, the performance of the magnetic junction 300 can be improved.

FIG. 12 shows an exemplary embodiment of a magnetic memory 400 utilizing a dual magnetic junction. In the illustrated embodiment, the magnetic memory is STT-RAM 400 . Magnetic memory 400 includes read/write column selectors/drivers 402 and 406 and word line selector/driver 404 . The magnetic memory 400 also includes a memory cell 410 including a magnetic junction 412 and a selection/isolation device 414 . The magnetic junction 412 can be any magnetic junction 100/100'/100"/200/200'/200"/300. Read/write column selectors/drivers 402 and 406 may be used to selectively drive current through bit line 403 and thus through cell 410 . The word line selector/driver 404 selectively turns on a row of the magnetic memory 4000 by turning on a selection/isolation device 414 coupled to a selected word line 405 .

Because magnetic memory 400 can employ magnetic junctions 100/100'/100"/200/200'/200"/300, magnetic memory 400 shares the benefits of magnetic junctions 100/100'/100"/200/200'/200" . Therefore, the performance of the magnetic memory 400 can be improved.

FIG. 13 shows an exemplary embodiment of a method 500 for fabricating a dual magnetic tunnel junction suitable for use in magnetic memory. Method 500 is described in the context of magnetic junction 100/100'. However, method 500 can also be used to fabricate other magnetic junctions. Also, certain steps may be omitted for simplicity. Additionally, method 500 may incorporate and/or employ additional and/or additional steps. Method 500 is also described in the context of fabricating a single magnetic junction. However, method 500 typically forms multiple parallel magnetic junctions, such as for memory 300 .

A magnetic junction stack is provided via step 502 . The magnetic junction stack includes a pinned layer film, a spin filter film, and a free layer film. The stack may also include a spacer layer film and an additional pinned layer film if the magnetic junction 300 is to be fabricated. In some embodiments, the magnetic junction stack may also be annealed in step 502 .

The magnetic junctions 100/100&apos;/100&quot;/200/200&apos;/200&quot;/300 are defined by step 504 by the stack of magnetic junctions. Step 504 includes providing a mask covering a portion of the magnetic junction stack and then removing the exposed portion of the magnetic junction stack. The magnetic junction 100/100'/100"/200/200'/200"/300 includes a pinned layer 110/110'/110"/110'''/210/210 defined by a first pinned layer film '210' 310, symmetric filter 120/120'/120'/220/220'/220' 320 defined by spin filter membrane and free layer 130/130'/130'' defined by free layer membrane/ 130'''/230/230'/230"/330. In some embodiments, the magnetic junction 300 also includes a spacer layer 340 and an additional pinned layer 350 .

The magnetization direction of the pinned layer 110/110'/110"/110'''/210/210'210"310 is set by step 506. For example, step 506 may be performed by applying a magnetic field in the desired direction while heating the magnetic junction 100/100'/100"/200/200'/200"/300, and then cooling the magnetic junction 100 in the presence of the magnetic field /100'/100"/200/200'/200"/300.

Thus, magnetic junctions 100/100'/100"/200/200'/200"/300 can be fabricated. The magnetic junction and/or magnetic memory 400 fabricated by method 500 shares the benefits of magnetic junction 100/100&apos;/100&quot;/200/200&apos;/200&quot; and/or magnetic memory 300. Accordingly, the performance of the magnetic junction 100/100'/100"/200/200'/200" and/or the magnetic memory 300 may be improved.

Methods and systems for providing magnetic junctions and memories fabricated using magnetic memory junctions have been described. The method and system have been described in terms of the exemplary embodiments shown, those of ordinary skill in the art will readily appreciate that changes may be made to the embodiments and any changes will be within the spirit and scope of the methods and systems described. Accordingly, many modifications can be made by one of ordinary skill in the art without departing from the spirit and scope of the claims.

This application is a co-pending patent application serial no. 12/685418 entitled "Method and System for Providing Magnetic Tunneling Junctions Usable in Spin Transfer Torque Magnetic Memories" filed on January 11, 2010 and assigned to the assignee of this application continue to apply.

This invention was made with United States Government support under Grant/Contract No. HR0011-09-C-0023 awarded by DARPA. The US Government reserves certain rights in this invention. Assignments are authorized to U.S. government structures only.

Claims (27)

1. A magnetic junction comprising: a free layer having a first magnetic moment switchable between a plurality of stable magnetic states when a write current flows through the magnetic junction; a symmetry filter that transmits charge carriers of a first symmetry with a higher probability than charge carriers of a second symmetry; a pinned layer having a second magnetic moment pinned in a specific direction, the symmetry filter positioned between said free layer and said pinned layer; wherein at least one of the free layer and the pinned layer has charge carriers of a first symmetry at the Fermi level in a spin channel, and no charge carriers at the Fermi level in the other spin channel Charge carriers of a first symmetry at an energy level lying substantially in a plane and having a non-zero magnetic moment component substantially perpendicular to the plane, said symmetry filter associated with said free layer and said pinned At least one of the pinned layers has a lattice mismatch of less than seven percent. 2. The magnetic junction of claim 1, wherein the lattice mismatch is less than four percent. 3. The magnetic junction of claim 1, wherein at least one of the free layer and the pinned layer comprises AlMn. 4. The magnetic junction of claim 1, wherein the symmetry filter comprises at least one of Ge, GaAs, and ZnSe. 5. The magnetic junction of claim 1, wherein the first magnetic moment is substantially perpendicular to a plane. 6. The magnetic junction of claim 1, wherein the second magnetic moment is substantially perpendicular to the plane. 7. The magnetic junction of claim 1, wherein at least one of the free layer and the pinned layer comprises at least one of MnGa and MnIn. 8. The magnetic junction of claim 1, wherein the symmetry filter is a tunneling barrier layer. 9. The magnetic junction of claim 1, wherein at least one of the free layer and the pinned layer is a synthetic antiferromagnet. 10. The magnetic junction of claim 1, further comprising: spacer layer; and A further pinned layer, the spacer layer is located between the free layer and the further pinned layer, the further pinned layer has a third magnetic moment. 11. The magnetic junction of claim 10, wherein the further pinned layer comprises AlMn. 12. The magnetic junction of claim 10, wherein the spacer layer is an additional symmetry filter. 13. The magnetic junction of claim 11 , wherein the additional symmetry filter has less than seven percent additional lattice to at least one of the free layer and the additional pinned layer lost pair. 14. The magnetic junction of claim 13, wherein the additional lattice mismatch is less than four percent. 15. The magnetic junction of claim 12, wherein the additional symmetry filter comprises at least one of Ge, GaAs, and ZnSe. 16. The magnetic junction of claim 1, wherein at least one of the free layer, the pinned layer, and the additional pinned layer is a synthetic antiferromagnet. 17. A magnetic junction for use in a magnetic memory device, comprising: a free layer, substantially parallel to the plane, comprising AlMn having a (001) axis substantially perpendicular to the plane, and having a first magnetic state switchable between a plurality of stable magnetic states when a write current flows through the magnetic junction a magnetic moment having a first non-zero component substantially perpendicular to the plane, the free layer having charge loading of a first symmetry at the Fermi energy in the first multi-sub-spin channel carriers without charge carriers of said first symmetry in the first minority spin channel; a symmetry filter that transmits charge carriers having said first symmetry and blocks charge carriers having a second symmetry different from said first symmetry, said symmetry filter comprising Ge, At least one of GaAs and ZnSe; The pinned layer, substantially parallel to the plane, includes AlMn having a (001) axis substantially perpendicular to the plane, and has a second magnetic moment pinned in a specific direction, the second magnetic moment having substantially perpendicular to the second non-zero component of the plane, the pinned layer has charge carriers of said first symmetry at the Fermi energy in the second multisub-spin channel, and in the second There are no charge carriers of the first symmetry in the minority spin channel, and the symmetry filter is located between the free layer and the pinned layer. 18. A magnetic memory comprising: A plurality of magnetic memory cells, each of the plurality of magnetic memory cells includes at least one selection device and at least one magnetic junction, the at least one magnetic junction includes a free layer, a pinned layer, and a symmetry filter between pinned layers, the free layer having a first magnetic moment that switches between multiple stable magnetic states when a write current flows through the magnetic junction, the symmetry filter in The charge carrier with the first symmetry is transported with a higher probability than the charge carrier with the second symmetry, the pinned layer has a second magnetic moment pinned in a specific direction, the free layer and at least one of said pinned layers has charge carriers of said first symmetry at the Fermi level in a first spin channel and no charge carriers at the Fermi level in the other spin channel charge carriers of a first symmetry at the stage, substantially in a plane and having a non-zero magnetic moment component substantially perpendicular to the plane, the symmetry filter is associated with the free layer and the pinned at least one of the layers has a lattice mismatch of less than seven percent; a plurality of bit lines coupled to the plurality of magnetic memory cells; and A plurality of word lines are coupled to the plurality of magnetic storage units. 19. The magnetic memory of claim 18, wherein the lattice mismatch is less than four percent. 20. The magnetic memory of claim 18, wherein the symmetry filter comprises at least one of Ge, GaAs, and ZnSe. 21. A magnetic junction for use in a magnetic memory device, comprising: a free layer substantially parallel to the plane and having a first magnetic moment switchable between a plurality of stable magnetic states when a write current flows through the magnetic junction, the first magnetic moment having a direction substantially perpendicular to the the first nonzero component of the plane; Symmetry filter; a pinned layer substantially parallel to the plane and having a second magnetic moment pinned in a specific direction, the symmetry filter is located between the pinned layer and the free layer, the The second magnetic moment has a second non-zero component substantially perpendicular to the plane, at least one of the free layer and the pinned layer has a first multi-sub-spin channel at the Fermi energy a symmetry of charge carriers, the absence of charge carriers of said first symmetry in a first minority spin channel, said symmetry filter transporting charge carriers of said first symmetry, and to block charge carriers having a second symmetry different from the first symmetry, the symmetry filter having less than seven percent share with at least one of the free layer and the pinned layer lattice mismatch. 22. A magnetic junction for use in a magnetic memory device, comprising: a free layer substantially parallel to the plane and having a first magnetic moment switchable between a plurality of stable magnetic states when a write current is passed through the magnetic junction, the first magnetic moment having a magnetic moment substantially perpendicular to the plane The first non-zero component of , the free layer has charge carriers of the first symmetry at the Fermi energy in the first many-sub-spin channel, while the first minority-sub-spin channel does not have the first a symmetrical charge carrier; a symmetry filter that transmits charge carriers having said first symmetry and blocks charge carriers having a second symmetry different from said first symmetry; a pinned layer substantially parallel to the plane and having a second magnetic moment pinned in a specific direction, the second magnetic moment having a second non-zero component substantially perpendicular to the plane, the pinned The pinned layer has charge carriers of said first symmetry at the Fermi energy in the second many-carrier spin channel, while there is no charge carrier of said first symmetry in the second minority-carrier spin channel The symmetry filter is located between the free layer and the pinned layer, the symmetry filter has less than a percent share with at least one of the free layer and the pinned layer Seven's lattice mismatch. 23. A method for providing a magnetic junction for use in a magnetic memory device, comprising: A magnetic junction stack is provided that includes a free layer film, a pinned layer film, and a symmetry filter film that transports charge carriers having a first symmetry and blocks charge carriers having a second symmetry. positive charge carriers, the symmetry filter layer is located between the free layer film and the pinned layer film, at least one of the free layer film and the pinned layer film is In a spin channel with charge carriers of the first symmetry at the Fermi level, while in the other spin channel there are no charge carriers of said first symmetry at the Fermi level, essentially lying in a plane with a non-zero magnetic moment component substantially perpendicular to the plane, the symmetry filter having less than seven percent crystallization with at least one of the free layer and the pinned layer case mismatch; defining the magnetic junction such that the magnetic junction includes a free layer defined by the free layer film, a spin filter defined by the spin filter layer, and a pinned layer defined by the pinned layer film. layer, the free layer has a first magnetic moment, and the pinned layer has a second magnetic moment; setting the second magnetic moment of the pinned layer to be pinned in a specific direction; Wherein the magnetic structure is configured to allow the first magnetic moment to be switchable between a plurality of stable magnetic states when a write current flows through the magnetic junction. 24. The method of claim 23, wherein the lattice mismatch is less than four percent. 25. The method of claim 20, wherein at least one of the free layer film and the pinned layer film lies substantially in a plane and comprises AlMn having a (001) axis substantially perpendicular to the plane . 26. The method of claim 20, wherein the symmetry filter comprises at least one of Ge, GaAs, and ZnSe. 27. The method of claim 19, wherein the step of providing the magnetic junction stack further comprises: depositing a spacer film; and depositing an additional pinned layer film for an additional pinned layer, the spacer layer being between said additional pinned layer film and said free layer film, said additional pinned layer having a first Three magnetic moments.

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