WO2019125381A1

WO2019125381A1 - Spin orbit coupling based memory with sub-lattice spin torque

Info

Publication number: WO2019125381A1
Application number: PCT/US2017/067082
Authority: WO
Inventors: Sasikanth Manipatruni; Dmitri E. Nikonov; Ian A. Young; Tanay GOSAVI
Original assignee: Intel Corporation
Priority date: 2017-12-18
Filing date: 2017-12-18
Publication date: 2019-06-27

Abstract

An apparatus is provided which comprises: a magnetic junction; and an interconnect adjacent to the magnetic junction, wherein the interconnect comprises a material exhibiting Neel spin orbit coupling. Another apparatus is provided which comprises: a magnetic junction including: a stack of structures including: a first structure comprising a magnet; a second structure comprising one of a dielectric or metal; a third structure comprising a magnet with in-plane magnetic anisotropy, wherein the third structure has an anisotropy axis along a plane of a device, and wherein the third structure is adjacent to the second structure such that the second structure is between the first and third structures; and an interconnect adjacent to the first structure of the magnetic junction, wherein the interconnect comprises an antiferromagnetic (AFM) material.

Description

SPIN ORBIT COUPLING BASED MEMORY WITH SUB-LATTICE SPIN TORQUE

BACKGROUND

[0001] Embedded memory with state retention can enable energy and computational efficiency. However, leading spintronic memory options, for example, spin transfer torque based magnetic random access memory (STT-MRAM), suffer from the problem of high voltage and high write current during the programming (e.g., writing) of a bit-cell. For instance, large write current (e.g., greater than 100 mA) and voltage (e.g., greater than 0.7 V) are required to write a tunnel junction based magnetic tunnel junction (MTJ). Limited write current also leads to high write error rates or slow switching times (e.g., exceeding 20 ns) in MTJ based MRAM. The presence of a large current flowing through a tunnel barrier leads to reliability issues in magnetic tunnel junctions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The embodiments of the disclosure will be understood more fully from the detailed description given below and from the accompanying drawings of various embodiments of the disclosure, which, however, should not be taken to limit the disclosure to the specific embodiments, but are for explanation and understanding only.

[0003] Fig. 1A illustrates a magnetization response to an applied magnetic field for a ferromagnet.

[0004] Fig. IB illustrates a magnetization response to an applied magnetic field for a paramagnet.

[0005] Figs. 2A-B illustrate a three-dimensional (3D) view and corresponding top view, respectively, of a device having an out-of-plane magnetic tunnel junction (MTJ) stack coupled to a spin orbit coupling (SOC) interconnect.

[0006] Fig. 3 illustrates a cross-section of the SOC interconnect with electrons having their spins polarized in-plane and deflected up and down resulting from a flow of charge current.

[0007] Fig. 4A illustrates a plot showing write energy-delay conditions for one transistor and one MTJ with spin Hall effect (SHE) material compared to traditional MTJs.

[0008] Fig. 4B illustrates a plot comparing reliable write times for spin Hall MRAM and spin torque MRAM.

[0009] Figs. 5A-B illustrate a 3D view and corresponding cross-section view, respectively, of a device comprising a magnetic junction with magnets having in-plane magnetizations, and an interconnect with Neel Spin Orbit material(s), according to some embodiments of the disclosure.

[0010] Figs. 6A-B illustrate a 3D view and corresponding cross-section view, respectively, of a device comprising a magnetic junction with magnets having in-plane magnetizations, and an interconnect with Neel Spin Orbit material(s), according to some embodiments of the disclosure.

[0011] Figs. 7A-B illustrate a 3D view and corresponding cross-section view, respectively, of a device comprising a magnetic junction with magnets having in-plane magnetizations, and an interconnect with topological antiferromagnetic (AFM) material or topological Need Spin Orbit material(s), according to some embodiments of the disclosure.

[0012] Fig. 8 illustrates a cross-section of a device having a magnetic junction with magnets having in-plane magnetizations, where a free magnet structure of the magnetic junction comprises a stack of magnets with in-plane magnetizations, and an interconnect with Neel Spin Orbit material(s), according to some embodiments of the disclosure.

[0013] Fig. 9 illustrates a flowchart of a method for forming any of the devices of

Figs. 5-8, in accordance with some embodiments.

[0014] Fig. 10 illustrates a cross-section of a die layout having any of the devices of

Figs. 5-8 formed in metal 3 (M3) and metal 2 (M2) layer regions, according to some embodiments of the disclosure.

[0015] Fig. 11 illustrates a cross-section of a die layout having any of the devices of

Figs. 5-8 formed in metal 2 (M2) and metal 1 (Ml) layer regions, according to some embodiments of the disclosure.

[0016] Fig. 12 illustrates a smart device or a computer system or a SoC (System-on-

Chip) with any of the devices of Figs. 5-8, according to some embodiments of the disclosure.

DETAILED DESCRIPTION

[0017] Some embodiments describe a spin orbit torque (SOT) based magnetic random access memory (MRAM), where the SOT is provided by an interconnect having

antiferromagnetic (AFM) material. In some embodiments, the antiferromagnetic material is a stack of materials that together generates an in-plane exchange coupling field. As such, spin current polarized in the plane of a device is generated, and this spin current propagates perpendicular to the plane of the device. In various embodiments, a magnetic junction is formed on top of the AFM based interconnect. In some embodiments, the AFM material is a stack of materials (e.g., a sub-lattice) where atoms of one material spin in a direction opposite to the spin of atoms in the same material but separated by another material in the stack. For example, the stack of materials of the AFM may include alternating layers of Mn and Au, and the spin of atoms in an Mn layer have opposite directions compared to the spin of atom in the next Mn layer in the stack.

[0018] In some embodiments, the AFM material is a Neel SOT material where the spin orbit coupling between the momentum and spin of the electrons reverses sign at each sub-lattice. This leads to a unique spin-to-charge and charge-to-spin conversion property which results in efficiency and low power switching of the free magnet of the magnetic junction.

[0019] In some embodiments, the magnetic junction includes: a stack of structures including: a first structure comprising a paramagnet; a second structure comprising one of a dielectric or metal; a third structure comprising a magnet with fixed in-plane magnetic anisotropy, wherein the third structure has an anisotropy axis along a plane of a device, and wherein the third structure is adjacent to the second structure such that the second structure is between the first and third structures. In some embodiments, the AFM interconnect is adjacent to the first structure of the magnetic junction. In various embodiments, the AFM also has an in-plane magnetization.

[0020] In some embodiments, the paramagnet of the first structure has unfixed (or free) in-plane magnetic anisotropy, wherein the paramagnet has an anisotropy axis along a plane of the device. For example, the paramagnet is a free magnet with in-plane

magnetization.

[0021] The term“free” or“unfixed” here with reference to a magnet refers to a magnet whose magnetization direction can change along its easy axis upon application of an external field or force (e.g., Oersted field, spin torque, etc.). Conversely, the term“fixed” or “pinned” here with reference to a magnet refers to a magnet whose magnetization direction is pinned or fixed along an axis and which may not change due to application of an external field (e.g., electrical field, Oersted field, spin torque,).

[0022] Here, perpendicularly magnetized magnet (or perpendicular magnet, or magnet with perpendicular magnetic anisotropy (PMA)) generally refers to a magnet having a magnetization which is substantially perpendicular to a plane of the magnet or a device. For example, a magnet with a magnetization which is in a z-direction in a range of 90 (or 270) degrees +/- 20 degrees relative to an x-y plane of a device.

[0023] Here, an in-plane magnet generally refers to a magnet that has magnetization in a direction substantially along the plane of the magnet. For example, a magnet with a magnetization which is in an x or y direction and is in a range of 0 (or 180 degrees) +/- 20 degrees relative to an x-y plane of a device.

[0024] The term“device” may generally refer to an apparatus according to the context of the usage of that term. For example, a device may refer to a stack of layers or structures, a single structure or layer, a connection of various structures having active and/or passive elements, etc. Generally a device is a three dimensional structure with a plane along the x-y direction and a height along the z direction of an x-y-z Cartesian coordinate system. The plane of the device may also be the plane of an apparatus which comprises the device.

[0025] In some embodiments, the magnetic junction comprises: a fourth structure between the first and second structures, wherein the fourth structure includes one or more of: Ru, Os, Hs, or Fe. For example, a coupling layer is formed between the first and second structures. In some embodiments, the magnetic junction comprises a fifth structure between the second and third structures, wherein the fifth structure includes one or more of: Ru, Os, Hs, or Fe. For example, a coupling layer is formed between the second and third structures.

In some embodiments, the AFM material is topological and in direct contact with the paramagnet of the first structure. In some embodiments, the AFM material includes one of: Mn, Au, or As. In some embodiments, the AFM comprises a stack of materials including a first material and a second material, wherein the first and second materials are different, and wherein the first and second materials include one or more of: Mn, Au, or As. In some embodiments, the AFM material is a quasi-two-dimensional triangular AFM including Nip _X)M_xGa₂S₄, where‘M’ includes one of: Mn, Fe, Co or Zn.

[0026] In some embodiments, when a positive current is passed through the AFM interconnect (e.g., formed of alternate layers of Mn and Au), alternate planes of Mn are spin polarized in opposite directions. This direction is reversed for opposite charge current directions. In this example, the net switching efficiency of the SOT mechanism is not bound by the Eb/Ic for spin transfer torque switching. As such, higher switching efficiency is achieved than using traditional SOT materials for the interconnect. Other technical effects will be evident from the various embodiments and figures.

[0027] In some embodiments, the magnetic junction is one of a spin valve or a magnetic tunneling junction (MTJ). In some embodiments, the paramagnet includes one or more of: Pt, Pd, W, Ce, Al, Li, Mg, Na, Cr, Co, Dy, O, Er, Eu, Eu, Gd, Fe, Nd, K, Pr, Sm, Tb, Tm, or V. In some embodiments, the paramagnet comprises dopants which include one or more of: Ce, Cr, Mn, Nb, Mo, Tc, Re, Nd, Gd, Tb, Dy, Ho, Er, Tm, or Yb. In some embodiments, the magnet of the third structure is a ferromagnet which includes one or more of: Co, Fe, Ge, or Ga or a Heusler alloy. In some embodiments, the Heusler alloy includes one or more of Co, Cu, Fe, Ga, Ge, In, Mn, Al, In, Sb, Si, Sn, Ni, Pd, Ru, or V.

[0028] In the following description, numerous details are discussed to provide a more thorough explanation of embodiments of the present disclosure. It will be apparent, however, to one skilled in the art, that embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring embodiments of the present disclosure.

[0029] Note that in the corresponding drawings of the embodiments, signals are represented with lines. Some lines may be thicker, to indicate more constituent signal paths, and/or have arrows at one or more ends, to indicate primary information flow direction. Such indications are not intended to be limiting. Rather, the lines are used in connection with one or more exemplary embodiments to facilitate easier understanding of a circuit or a logical unit. Any represented signal, as dictated by design needs or preferences, may actually comprise one or more signals that may travel in either direction and may be implemented with any suitable type of signal scheme.

[0030] Throughout the specification, and in the claims, the term "connected" means a direct connection, such as electrical, mechanical, or magnetic connection between the things that are connected, without any intermediary devices.

[0031] The term "coupled" means a direct or indirect connection, such as a direct electrical, mechanical, or magnetic connection between the things that are connected or an indirect connection, through one or more passive or active intermediary devices.

[0032] The term“adjacent” here generally refers to a position of a thing being next to

(e.g., immediately next to or close to with one or more things between them) or adjoining another thing (e.g., abutting it).

[0033] The term "circuit" or“module” may refer to one or more passive and/or active components that are arranged to cooperate with one another to provide a desired function.

[0034] The term "signal" may refer to at least one current signal, voltage signal, magnetic signal, or data/clock signal. The meaning of "a," "an," and "the" include plural references. The meaning of "in" includes "in" and "on."

[0035] The term“scaling” generally refers to converting a design (schematic and layout) from one process technology to another process technology and subsequently being reduced in layout area. The term“scaling” generally also refers to downsizing layout and devices within the same technology node. The term“scaling” may also refer to adjusting (e.g., slowing down or speeding up - i.e. scaling down, or scaling up respectively) of a signal frequency relative to another parameter, for example, power supply level. The terms “substantially,”“close,”“approximately,”“near,” and“about,” generally refer to being within +/- 10% of a target value.

[0036] Unless otherwise specified the use of the ordinal adjectives“first,”“second,” and“third,” etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking or in any other manner.

[0037] For the purposes of the present disclosure, phrases“A and/or B” and“A or B” mean (A), (B), or (A and B). For the purposes of the present disclosure, the phrase“A, B, and/or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0038] The terms“left,”“right,”“front,”“back,”“top,”“bottom,”“over,”“under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions.

[0039] For the purposes of present disclosure, the terms“spin” and“magnetic moment” are used equivalently. More rigorously, the direction of the spin is opposite to that of the magnetic moment, and the charge of the particle is negative (such as in the case of electron).

[0040] It is pointed out that those elements of the figures having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such.

[0041] Fig. 1A illustrates a magnetization hysteresis plot 100 for ferromagnet 101.

The plot shows magnetization response to an applied magnetic field for ferromagnet 101.

The x-axis of plot 100 is magnetic field Ή’ while the y-axis is magnetization‘m’. For ferromagnet (FM) 101, the relationship between Ή’ and‘m’ is not linear and results in a hysteresis loop as shown by curves 102 and 103. The maximum and minimum magnetic field regions of the hysteresis loop correspond to saturated magnetization configurations 104 and 106, respectively. In saturated magnetization configurations 104 and 106, FM 101 has stable magnetizations. In the zero magnetic field region 105 of the hysteresis loop, FM 101 does not have a definite value of magnetization, but rather depends on the history of applied magnetic fields.

[0042] For example, the magnetization of FM 101 in configuration 105 can be either in the +x direction or the -x direction for an in-plane FM. As such, changing or switching the state of FM 101 from one magnetization direction (e.g., configuration 104) to another magnetization direction (e.g., configuration 106) is time consuming resulting in slower nanomagnets response time. It is associated with the intrinsic energy of switching proportional to the area in the graph contained between curves 102 and 103.

[0043] Fig. IB illustrates magnetization plot 120 for paramagnet 121. Plot 120 shows the magnetization response to an applied magnetic field for paramagnet 121. The x-axis of plot 120 is magnetic field Ή’ while the y-axis is magnetization‘m’. A paramagnet, as opposed to a ferromagnet, exhibits magnetization when a magnetic field is applied to it. Paramagnets generally have magnetic permeability greater or equal to one and hence are attracted to magnetic fields. Compared to plot 100, the magnetic plot 120 of Fig. IB does not exhibit hysteresis which allows for faster switching speeds and smaller switching energies between the two saturated magnetization configurations 124 and 126 of curve 122. In the middle region 125, paramagnet 121 does not have any magnetization because there is no applied magnetic field (e.g., H=0). The intrinsic energy associated with switching is absent in this case.

[0044] In some embodiments, paramagnet 121 comprises a material which includes one or more of: Platinum(Pt), Palladium (Pd), Tungsten (W), Cerium (Ce), Aluminum (Al), Lithium (Li), Magnesium (Mg), Sodium (Na), CnCL (chromium oxide), CoO (cobalt oxide), Dysprosium (Dy), Dy₂0 (dysprosium oxide), Erbium (Er), EnCL (Erbium oxide), Europium (Eu), EU2O3 (Europium oxide), Gadolinium (Gd), Gadolinium oxide (Gd₂0₃), FeO and Fe₂0₃ (Iron oxide), Neodymium (Nd), Nd₂0₃ (Neodymium oxide), K0₂ (potassium superoxide), praseodymium (Pr), Samarium (Sm), Sm₂0₃ (samarium oxide), Terbium (Tb), Tb₂0₃ (Terbium oxide), Thulium (Tm), Tm₂0₃ (Thulium oxide), or V₂0₃ (Vanadium oxide). In some embodiments, paramagnet 121 comprises dopants which include one or more of: Ce,

Cr, Mn, Nb, Mo, Tc, Re, Nd, Gd, Tb, Dy, Ho, Er, Tm, or Yb. In various embodiments, the free magnet is a paramagnet while the fixed or pinned magnet of the device can be either a FM or a paramagnet.

[0045] Figs. 2A-B illustrate a three-dimensional (3D) view 200 and corresponding top view 220, respectively, of device having an out-of-plane magnetic tunnel junction (MTJ) stack coupled to a spin orbit coupling (SOC) interconnect, where the MTJ stack includes a free magnet layer much smaller than a length of the SOC interconnect. Here, view 200 also refers to device 200.

[0046] Here, the stack of layers having magnetic junction 221 is coupled to an electrode 222 comprising spin Hall effect (SHE) or SOC material, where the SHE material converts charge current Iw (or write current) to spin polarized current Is. The device of Fig. 2A forms a three-terminal memory cell with SHE induced write mechanism and MTJ based read-out. The device of Fig. 2A comprises magnetic junction 221, SHE Interconnect or electrode 222, and non-magnetic metal(s) 223a/b. In one example, MTJ 221 comprises layers 22la, 22lb, and 22lc. In some embodiments, layers 22la and 22lc are ferromagnetic layers. In some embodiments, layer 22 lb is a metal or a tunneling dielectric.

[0047] For example, when the magnetic junction is a spin valve, layer 22 lb is metal or a metal oxide (e.g., a non-magnetic metal such as Al and/or its oxide) and when the magnetic junction is a tunneling junction, then layer 22 lb is a dielectric (e.g. MgO, AI2O3, etc.). One or both ends along the horizontal direction of SHE Interconnect 222 is formed of non-magnetic metals 223a/b (e.g., Cu, Al, Au, etc.). Additional layers 22ld, 22le, 22lf, and 22lg can also be stacked on top of layer 22lc. In some embodiments, layer 22lg is a non magnetic metal electrode.

[0048] So as not to obscure the various embodiments, the magnetic junction is described as a magnetic tunneling junction (MTJ). However, the embodiments are also applicable for spin valves. A wide combination of materials can be used for material stacking of magnetic junction 221. For example, the stack of layers 22la, 22lb, 22lc, 22ld, 22le,

22 lf, and 22 lg are formed of materials which include: Co_xFe_yB_z, MgO, Co_xFe_yB_z, Ru, Co_xFe_yB_z, IrMn, and Ru, respectively, where‘x,’‘y,’ and‘z’ are fractions of elements in the alloys. Other materials may also be used to form MTJ 221. MTJ 221 stack comprises free magnetic layer 22la, MgO tunneling oxide 22lb, a fixed magnetic layer 22lc/d/e which is a combination of CoFe, Ru, and CoFe layers, respectively, referred to as Synthetic Anti- Ferromagnet (SAF), and an Anti-Ferromagnet (AFM) layer 22lf. The SAF layer has the property that the magnetizations in the two CoFe layers are opposite, and allows for cancelling the dipole fields around the free magnetic layer such that a stray dipole field will not control the free magnetic layer.

[0049] In some embodiments, the free and fixed magnetic layers (22 la and 22 lc, respectively) are formed of CFGG (i.e., Cobalt (Co), Iron (Fe), Germanium (Ge), or Gallium (Ga) or a combination of them). In some embodiments, FM 22la/c are formed from Heusler alloys. Heusler alloys are ferromagnetic metal alloys based on a Heusler phase. Heusler phases are intermetallic with certain composition and face-centered cubic crystal structure. The ferromagnetic property of the Heusler alloys are a result of a double-exchange mechanism between neighboring magnetic ions. In some embodiments, the Heusler alloy includes one of: CmMnAl, CmMnln, C_¾MnSn, NCMnAl, NkMnln, NkMnSn, NkMnSb, Ni₂MnGa Co₂MnAl, Co₂MnSi, Co₂MnGa, Co₂MnGe, Pd₂MnAl, Pd₂MnIn, Pd₂MnSn, Pd₂MnSb, Co₂FeSi, Co₂FeAl, Fe₂VAl, Mn₂VGa, Co₂FeGe, MnGa, or MnGaRu.

[0050] In some embodiments, fixed magnet layer 22 lc is a magnet with perpendicular magnetic anisotropy (PMA). For example, fixed magnet structure 22lc has a magnetization pointing along the z-direction and is perpendicular to the x-y plane of the device 200. In some embodiments, the magnet with PMA comprises a stack of materials, wherein the materials for the stack are selected from a group consisting of: Co and Pt; Co and Pd; Co and Ni; MgO, CoFeB, Ta, CoFeB, and MgO; MgO, CoFeB, W, CoFeB, and MgO; MgO, CoFeB, V, CoFeB, and MgO; MgO, CoFeB, Mo, CoFeB, and MgO; Mn_xGa_y; Materials with Llo symmetry; and materials with tetragonal crystal structure. In some embodiments, the magnet with PMA is formed of a single layer of one or more materials. In some embodiments, the single layer is formed of MnGa.

[0051] Llo is a crystallographic derivative structure of an FCC (face centered cubic lattice) structure and has two of the faces occupied by one type of atom and the comer and the other face occupied with the second type of atom. When phases with the Ll₀ structure are ferromagnetic the magnetization vector usually is along the [0 0 1] axis of the crystal.

Examples of materials with Ll₀ symmetry include CoPt and FePt. Examples of materials with tetragonal crystal structure and magnetic moment are Heusler alloys such as CoFeAl, MnGe, MnGeGa, and MnGa.

[0052] SHE Interconnect 222 (or the write electrode) includes 3D materials such as one or more of b-Tantalum (b-Ta), Ta, b-Tungsten (b-W), W, Pt, Copper (Cu) doped with elements such as Iridium, Bismuth and any of the elements of 3d, 4d, 5d and 4f, 5f periodic groups in the Periodic Table which may exhibit high spin orbit coupling. In some embodiments, SHE interconnect 222 comprises a spin orbit 2D material which includes one or more of: graphene, BiSe₂, BiS₂, BiSe..Te _x. TiS₂, WS₂, MoS₂, TiSe2, WSe₂, MoSe₂, B₂S₃, Sb₂S₃, Ta₂S, Re₂S₇, LaCPS₂, LaOAsS₂, ScOBiS₂, GaOBiS₂, AlOBiS₂, LaOSbS₂, BiOBiS₂, YOBiS₂, InOBiS₂, LaOBiSe₂, TiOBiS₂, CeOBiS₂, PrOBiS₂, NdOBiS₂, LaOBiS₂, or SrFBiS₂. In some embodiments, the SHE interconnect 222 comprises spin orbit material which includes one of a 2D material or a 3D material, wherein the 3D material is thinner than the 2D material. In some embodiments, the SHE interconnect 222 comprises a spin orbit material which includes materials that exhibit Rashba-Bychkov effect.

[0053] In some embodiments, the 2D materials include one or more of: Mo, S, W, Se,

Graphene, MoS₂, WSe₂, WS₂, or MoSe₂. In some embodiments, the 2D materials include an absorbent which includes one or more of: Cu, Ag, Pt, Bi, Fr, or H absorbents. In some embodiments, the SOC structures comprise a spin orbit material which includes materials that exhibit Rashba-Bychkov effect. In some embodiments, material which includes materials that exhibit Rashba-Bychkov effect comprises materials ROCh₂, where‘R’ includes one or more of: La, Ce, Pr, Nd, Sr, Sc, Ga, Al, or In, and where“Ch” is a chalcogenide which includes one or more of: S, Se, or Te.

[0054] In some embodiments, SHE Interconnect 222 transitions into high conductivity non-magnetic metal(s) 223a/b to reduce the resistance of SHE Interconnect 222. The non-magnetic metal(s) 223a/b include one or more of: Cu, Co, a-Ta, Al, CuSi, or NiSi.

[0055] In one case, the magnetization direction of fixed magnetic layer 22 lc is perpendicular relative to the magnetization direction of free magnetic layer 22 la (e.g., magnetization directions of the free and fixed magnetic layers are not parallel, rather they are orthogonal). For example, the magnetization direction of free magnetic layer 22 la is in-plane while the magnetization direction of fixed magnetic layer 22 lc is perpendicular to the in plane. In another case, magnetization direction of fixed magnetic layer 22 la is in-plane while the magnetization direction of free magnetic layer 22lc is perpendicular to the plane.

[0056] The thickness of a ferromagnetic layer (e.g., fixed or free magnetic layer) may determine its equilibrium magnetization direction. For example, when the thickness of the ferromagnetic layer 22la/c is above a certain threshold (depending on the material of the magnet, e.g. approximately 1.5 nm for CoFe), then the ferromagnetic layer exhibits magnetization direction which is in-plane. Likewise, when the thickness of the ferromagnetic layer 22la/c is below a certain threshold (depending on the material of the magnet), then the ferromagnetic layer 22la/c exhibits magnetization direction which is perpendicular to the plane of the magnetic layer.

[0057] Other factors may also determine the direction of magnetization. For example, factors such as surface anisotropy (depending on the adjacent layers or a multi-layer composition of the ferromagnetic layer) and/or crystalline anisotropy (depending on stress and the crystal lattice structure modification such as FCC (face centered cubic lattice), BCC (body centered cubic lattice), or Llo-type of crystals, where Llo is a type of crystal class which exhibits perpendicular magnetizations), can also determine the direction of magnetization.

[0058] In this example, the applied current /,, is converted into spin current I_s by SHE

Interconnect 222 (also referred to as the spin orbit coupling interconnect). This spin current switches the direction of magnetization of the free layer and thus changes the resistance of MTJ 221. However, to read out the state of MTJ 221, a sensing mechanism is needed to sense the resistance change.

[0059] The magnetic cell is written by applying a charge current via SHE

Interconnect 222. The direction of the magnetic writing in free magnet layer 22 la is decided by the direction of the applied charge current. Positive currents (e.g., currents flowing in the +y direction) produce a spin injection current with transport direction (along the +z direction) and spins pointing to the +x direction. The injected spin current in turn produces spin torque to align the free magnet 22 la (coupled to the SHE layer 222 of SHE material) in the +x direction. Negative currents (e.g., currents flowing in the -y direction) produce a spin injection current with transport direction (along the +z direction) and spins pointing to the -x direction. The injected spin current in turn produces spin torque to align the free magnet 22la (coupled to the SHE material of layer 222) in the -x direction. In some embodiments, in materials with the opposite sign of the SHE/SOC effect, the directions of spin polarization and thus of the free layer magnetization alignment are reversed compared to the above.

[0060] Fig. 3 illustrates a cross-section of the SOC interconnect with electrons having their spins polarized in-plane and deflected up and down resulting from a flow of charge current. In this example, positive charge current represented by J, produces spin-front (e.g., in the +X direction) polarized current 301 and spin-back (e.g., in the -x direction) polarized current 302. The injected spin current l_s generated by a charge current I_c in the write electrode 222 is given by:

where, the vector of spin current I_s = If— /_j, points in the direction of transferred magnetic moment and has the magnitude of the difference of currents with spin along and opposite to the spin polarization direction, z is the unit vector perpendicular to the interface, P_SHE is the spin Hall injection efficiency which is the ratio of magnitude of transverse spin current to lateral charge current, w is the width of the magnet, t is the thickness of the SHE

Interconnect (or write electrode) 222, _Sf is the spin flip length in SHE Interconnect 222,

6_SHE i^s the spin Hall angle for SHE Interconnect 222 to free ferromagnetic layer interface. The injected spin angular momentum responsible for the spin torque given by:

S = h T_s/2e . . . (2)

[0061] The generated spin up and down currents 301/302 (e.g., J_s) are described as a vector cross-product given by:

Js ⁼ Q_SHE U_C ^X z ) . . . (3) [0062] This spin to charge conversion is based on Tunnel Magneto Resistance (TMR) which is highly limited in the signal strength generated. The TMR based spin to charge conversion has low efficiency (e.g., less than one).

[0063] Fig. 4A illustrates a plot 420 showing write energy-delay conditions for one transistor and one MTJ with spin Hall effect (SHE) material compared to traditional MTJs.

[0064] Fig. 4B illustrates plot 430 showing write energy-delay conditions for one transistor and one magnetic tunnel junction (MTJ) with spin Hall effect (SHE) material compared to traditional MTJs. Here, x-axis is energy per write operation in femto-Joules (fj) while the y-axis is delay in nano- seconds (ns).

[0065] Here, the energy-delay trajectory of SHE and MTJ devices are compared for in-plane magnet switching as the applied write voltage is varied. The energy-delay relationship (for in-plane switching) can be written as:

where R_wr;teis the write resistance of the device (resistance of SHE electrode or resistance of MTJ-P or MTJ-AP, where MTJ-P is a MTJ with parallel magnetizations while MTJ-AP is an MTJ with anti-parallel magnetizations, m₀ is vacuum permeability, e is the electron charge. The equation shows that the energy at a given delay is directly proportional to the square of

MJJe

the Gilbert damping a. Here the characteristic time, t₀ 7 varies as the spin

polarization varies for various SHE metal electrodes (e.g., 423, 424, 425). Plot 420 shows five curves 421, 422, 423, 424, and 425. Curves 421 and 422 show write energy-delay conditions using traditional MTJ devices without SHE material.

[0066] For example, curve 421 shows the write energy-delay condition caused by switching a magnet from anti-parallel (AP) to parallel (P) state, while curve 422 shows the write energy-delay condition caused by switching a magnet from P to AP state. Curves 422, 423, and 424 show write energy-delay conditions of an MTJ with SHE material. Clearly, write energy-delay conditions of an MTJ with SHE material is much lower than the write energy-delay conditions of an MTJ without SHE material. While the write energy-delay of an MTJ with SHE material improves over a traditional MTJ without SHE material, further improvement in write energy-delay is desired.

[0067] Fig. 4B illustrates plot 430 comparing reliable write times for spin Hall

MRAM and spin torque MRAM. There are three cases considered in plot 430. Waveform 431 is the write time for in-plane MTJ, waveform 432 is the write time for PMA MTJ, and waveform 433 is the write time for spin Hall MTJ. The cases considered here assume a 30 X 60 nm magnet with 40 kT energy barrier and 3.5 nm SHE electrode thicknesses. The energy- delay trajectories of the devices are obtained assuming a voltage sweep from 0 V to 0.7 V in accordance to voltage restrictions of scaled CMOS. The energy-delay trajectory of the SHE- MTJ devices exhibits broadly two operating regions A) Region 1 where the energy-delay product is approximately constant ( t_ά ^and Region 2 where the energy is

M_sVe

proportional to the delay t_ά > The two regions are separated by energy

/ I_CPPB^‘

M_sVe

minima at z_opt = / I_eRm_B where minimum switching energy is obtained for the spin torque devices.

[0068] The energy-delay trajectory of the STT-MTJ (spin transfer torque MTJ) devices is limited with a minimum delay of 1 ns for in-plane devices at 0.7 V maximum applied voltage, the switching energy for P-AP and AP-P are in the range of 1 pj/write. In contrast, the energy-delay trajectory of SHE-MTJ (in-plane anisotropy) devices can enable switching times as low as 20 ps (b-W with 0.7 V, 20 fj/bit) or switching energy as small as 2 fj (b-W with 0.1 V, 1.5 ns switching time).

[0069] In some embodiments to further improve switching speeds of the free magnet structure 22 la, and to reduce overall power consumption of the device, a Need spin orbit coupling material is used for interconnect 222, and the free magnet structure 22 la is replace with a free in-plane paramagnet structure. The exchange bias generated by the modified interconnect on to the free in-plane paramagnet structure allows for faster switching of the free in-plane paramagnet, and also to retain its state when current flow through the modified interconnect is paused. Figs. 5-8 illustrate various embodiments using the modified interconnect and in-plane free paramagnet structure.

[0070] Figs. 5A-B illustrate a 3D view 500 and corresponding cross-section view

520, respectively, of a device comprising a magnetic junction with magnets having in-plane magnetizations, and an interconnect with Neel Spin Orbit material(s), according to some embodiments of the disclosure. Here, view 500 of the junction device is also referred to as device 500. The device of Figs. 5A-B is similar to the device of Fig. 2A except that SHE interconnect 222 is replaced with interconnect 522 (also referred to as the modified interconnect) comprising antiferromagnetic (AFM) material, and magnetic junction 221 is replaced with magnetic junction 521. [0071] In some embodiments, the AFM material for interconnect 522 is a stack of materials (e.g., a sub-lattice) 522ai-_n and 522bi-_n (where‘n’ is an integer) that together generate an in-plane exchange coupling field. As such, spin current polarized in the plane of a device is generated, and this spin current propagates perpendicular to the x-y plane of the device. In some embodiments, the AFM material includes one of: Mn, Au, or As. For example, the first material 522ai-_n is one of: Mn, Au, or As, and the first material 522bi-_n is one of: Mn, Au, or As, where the first and second materials are different. In some embodiments, the atoms of one material of the stack spin in a direction opposite to the spin of atoms in the same material but separated by another material in the stack. For example, the stack of materials of the AFM may include alternating layers of Mn and Au, and the spin of atoms in an Mn layer have opposite directions compared to the spin of atom in the next Mn layer in the stack.

[0072] In some embodiments, the AFM material of interconnect 522 is a quasi-two- dimensional triangular AFM including Ni(i-_X)MxGa2S₄, where‘M’ includes one of: Mn, Fe,

Co or Zn. In some embodiments, the AFM material is a Neel spin orbit torque (SOT) or spin orbit coupling (SOC) material where the spin orbit coupling between the momentum and spin of the electrons reverses sign at each sub-lattice. This leads to a unique spin-top-charge and charge-to-spin conversion property which results in efficiency and low power switching of the free magnet of magnetic junction 521.

[0073] In some embodiments, magnetic junction 521 is formed on top of the AFM based interconnect 522. In some embodiments, magnetic junction 521 includes: a stack of structures including: a first structure (e.g., 52laa/ab/ac) comprising paramagnet 52laa;

second structure 22 lb comprising one of a dielectric or metal; and third structure 22 lc comprising a magnet with fixed in-plane magnetic anisotropy, wherein the third structure has an anisotropy axis along a plane of a device, and wherein the third structure 22lc is adjacent to the second structure 22 lb such that the second structure 22 lb is between the first and third structures. For example, the magnetization of the magnet of the third structure 22lc is along the +/- y direction, where x-y plane is the plane of device 500.

[0074] In some embodiments, the AFM interconnect 522 is adjacent to the first structure (e.g., layer 52laa) of the magnetic junction 531. In some embodiments, the AFM material of interconnect 522 is topological and in direct contact with the paramagnet 52laa of the first structure. For example, the AFM material of interconnect 522 is formed on the top surface of interconnect 222 such that AFM material of interconnect 522 is in direct contact with the bottom surface of paramagnet 52laa. [0075] In some embodiments, the first structure comprises a first free paramagnet

52laa having in-plane magnetization that can point substantially along the + y-axis or - y- axis according to an external field (e.g., exchange bias from AFM interconnect 522); a coupling layer 52lab; and a second free magnet 52lac having in-plane magnetization that can point substantially along the + y-axis or - y-axis. In various embodiments, the second free magnet 52lac is adjacent to layer 22lb (e.g., dielectric or metal/metal-oxide). In some embodiments, the second free magnet 52lac is a ferromagnet. For example, the first structure is a hybrid of a ferromagnet and a paramagnet separated or coupled together via a coupling layer (e.g., Ru, Os, Hs, Fe). In some embodiments, the second free magnet 52lac is also a paramagnet such that the first structure comprises at least two paramagnets separated by a coupling layer (e.g., Ru, Hs, Os, Fe). In various embodiments, the second free magnet 52lac is adjacent to layer 22lb (e.g., dielectric or metal/metal-oxide).

[0076] In some embodiments, paramagnet 52laa has an unfixed in-plane magnetic anisotropy, wherein the paramagnet 52laa has an anisotropy axis along the plane of the device. In some embodiments, magnetic junction 521 comprises: a fourth structure (not shown) between the first and second structures, wherein the fourth structure includes one or more of: Ru, Os, Hs, or Fe. The fourth structure acts like a coupling layer. In some embodiments, the magnetic junction 521 comprises a fifth structure (not shown) between the second and third structures, wherein the fifth structure includes one or more of: Ru, Os, Hs, or Fe. In some embodiments, magnetic junction 521 is one of a spin valve or a magnetic tunneling junction (MTJ). In some embodiments, paramagnet 52laa/ac includes one or more of: Pt, Pd, W, Ce, Al, Li, Mg, Na, Cr, Co, Dy, O, Er, Eu, Eu, Gd, Fe, Nd, K, Pr, Sm, Tb, Tm, or V. In some embodiments, paramagnet 52laa/ac comprises dopants which include one or more of: Ce, Cr, Mn, Nb, Mo, Tc, Re, Nd, Gd, Tb, Dy, Ho, Er, Tm, or Yb. In some embodiments, the magnet of the third structure is a fixed in-plane ferromagnet. In some embodiments, the magnet of the third structure includes one or more of: Co, Fe, Ge, or Ga or a Heusler alloy. In some embodiments, the Heusler alloy includes one or more of Co, Cu,

Fe, Ga, Ge, In, Mn, Al, In, Sb, Si, Sn, Ni, Pd, Ru, or V. In some embodiments, the magnet of the third structure is a fixed in-plane paramagnet instead of a ferromagnet. The remaining structure of the device is same as the device of Fig. 2A.

[0077] Figs. 6A-B illustrate a 3D view 600 and corresponding cross-section view

620, respectively, of a device comprising a magnetic junction 531 with magnets having in plane magnetizations, and an interconnect with Neel Spin Orbit material(s), according to some embodiments of the disclosure. The device of Figs. 6A-B is similar to the device of Figs 5A-B, but with a different type of free magnet structure (or first structure). In some embodiments, the free magnet structure or first structure of magnetic junction 531 comprises a single magnet 52la instead of a multi-layer structure comprising multiple free magnets with coupling layers between them. In various embodiments, the single magnet 52la comprises a free in-plane paramagnet. In some embodiments, the free magnet 52la is adjacent to layer 22lb.

[0078] Figs. 7A-B illustrate a 3D view 700 and corresponding cross-section view

720, respectively, of a device comprising a magnetic junction with magnets having in-plane magnetizations, and an interconnect with topological AFM material, according to some embodiments of the disclosure. In some embodiments, the interconnect or write electrode comprises a SHE material 222 adjacent to an AFM material 722 such that the AFM material is a topological material on the surface of SHE material 222. In some embodiments, the topological AFM material 722 is in direct contact with the in-plane free paramagnet 52laa of the first structure.

[0079] In some embodiments, the SHE material 222 under AFM material 722 is replaced with any regular or traditional metal (e.g., Cu, Al, Ag, Au). In some embodiments, AFM material 722 is a stack of materials (e.g., a sub-lattice) 722ai-_n and 722bi-_n (where‘n’ is an integer) that together generate an in-plane exchange coupling field. As such, spin current polarized in the plane of a device is generated, and this spin current propagates perpendicular to the plane of the device. In some embodiments, the AFM material includes one of: Mn, Au, or As.

[0080] For example, the first material 722ai-_n is one of: Mn, Au, or As, and the first material 722bi-_n is one of: Mn, Au, or As, where the first and second materials are different.

In some embodiments, the atoms of one material of the stack spin in a direction opposite to the spin of atoms in the same material but separated by another material in the stack. For example, the stack of materials of the AFM may include alternating layers of Mn and Au, and the spin of atoms in an Mn layer have opposite directions compared to the spin of atom in the next Mn layer in the stack.

[0081] In some embodiments, the AFM material 722 is a quasi-two-dimensional triangular AFM including Ni(i-_X)M_xGa2S₄, where‘M’ includes one of: Mn, Fe, Co or Zn. In some embodiments, the AFM material 722 is Neel spin orbit torque (SOT) or spin orbit coupling (SOC) material where the spin orbit coupling between the momentum and spin of the electrons reverses sign at each sub-lattice. This leads to a unique spin-top-charge and charge-to-spin conversion property which results in efficiency and low power switching of the free magnet 52laa of magnetic junction 521. In various embodiments of Figs. 5-8, the AFM material forms an in-plane anti-ferromagnet.

[0082] Fig. 8 illustrates a cross-section 800 of a device having a magnetic junction with magnets having in-plane magnetizations, where a free magnet structure of the magnetic junction comprises a stack of magnets with in-plane magnetizations, and an interconnect with Neel Spin Orbit material(s), according to some embodiments of the disclosure.

[0083] The magnetic junction is illustrated by reference sign 821 where the layers under layer 22 lb (e.g., dielectric or metal/metal-oxide) together form the structure comprising the free magnet of the junction. The device of Fig. 8A is similar to the device of Fig. 5A except that the fixed magnet 22lc is replaced with composite magnets having multiple layers.

[0084] In some embodiments, the composite stack of multi-layer fixed magnet 82lcc includes‘n’ layers of first material and second material. For example, the composite stack comprises layers 82laai-_n and 82labi-_n stacked in an alternating manner, where‘n’ has a range of 1 to 10. In some embodiments, the first material includes one of: Co, Ni, Fe, or Heusler alloy. In some embodiments, the second material includes one of: Pt, Pd, Ir, Ru, or Ni. In some embodiments, the Heusler alloy includes one or more of Co, Cu, Fe, Ga, Ge, In, Mn, Al, In, Sb, Si, Sn, Ni, Pd, Ru, or V. In some embodiments, the Heusler alloy includes one of: Cu₂MnAl, Cu₂MnIn, Cu₂MnSn, Ni₂MnAl, Ni₂MnIn, Ni₂MnSn, Ni₂MnSb, Ni₂MnGa Co₂MnAl, Co₂MnSi, Co₂MnGa, Co₂MnGe, Pd₂MnAl, Pd₂MnIn, Pd₂MnSn, Pd₂MnSb,

Co₂FeSi, Co₂FeAl, Fe₂VAl, Mn₂VGa, Co₂FeGe, MnGa, or MnGaRu. In some embodiments, the first material has a thickness tl in a range of 0.6 nm to 2 nm. In some embodiments, the second material has a thickness t2 in a range of 0.1 nm to 3 nm. While the embodiments here show first material being at the bottom followed by the second material, the order can be reversed without changing the technical effect. In various embodiments, the magnetization of the composite fixed layer 82lcc is in-plane as indicated by direction 803.

[0085] The embodiments of Figs. 5-8 can be mixed in any order. For example, the in-plane magnet structure comprising paramagnets 52laa and 52lac coupled by layer 52lab can be replaced with a single free paramagnet 52la with free magnetization along the place of the device. In some embodiments, AFM based interconnect 522 can be replaced with a composite interconnect where AFM material is fabricated on the top as AFM 722 over a metal (e.g., SHE interconnect 522).

[0086] Fig. 9 illustrates flowchart 900 of a method for forming any of the devices of

Figs. 5-8, in accordance with some embodiments. While the following blocks (or process operations) in the flowchart are arranged in a certain order, the order can be changed. In some embodiments, some blocks can be executed in parallel.

[0087] At block 901, a first structure is formed comprising a paramagnet (e.g., 52laa or 52la). In some embodiments, the paramagnet has unfixed in-plane magnetic anisotropy, wherein the paramagnet has an anisotropy axis along a plane of the device. In some embodiments, the paramagnet includes one or more of: Pt, Pd, W, Ce, Al, Li, Mg, Na, Cr, Co, Dy, O, Er, Eu, Eu, Gd, Fe, Nd, K, Pr, Sm, Tb, Tm, or V. In some embodiments, the paramagnet comprises dopants which include one or more of: Ce, Cr, Mn, Nb, Mo, Tc, Re, Nd, Gd, Tb, Dy, Ho, Er, Tm, or Yb. At block 902, a second structure is formed comprising a dielectric or metal (e.g., MgO, AI2O3, etc.)

[0088] At block 903, a third structure is formed comprising a magnet with fixed in plane magnetic anisotropy. In some embodiments, the third structure has an anisotropy axis along the plane of a device. In various embodiments, the third structure is adjacent to the second structure such that the second structure is between the first and third structures. Here, the first, second and third structures are part of a magnetic junction. In some embodiments, the magnetic junction is one of a spin valve or an MTJ. In some embodiments, the magnet of the third structure is a ferromagnet which includes one or more of: Co, Fe, Ge, or Ga or a Heusler alloy. In some embodiments, the Heusler alloy includes one or more of Co, Cu, Fe, Ga, Ge, In, Mn, Al, In, Sb, Si, Sn, Ni, Pd, Ru, or V.

[0089] In some embodiments, the method of forming the magnetic junction comprises: forming a fourth structure (e.g., coupling layer) between the first and second structures, wherein the fourth structure includes one or more of: Ru, Os, Hs, or Fe. In some embodiments, the method of forming the magnetic junction comprises forming a fifth structure (e.g., coupling layer) between the second and third structures, wherein the fifth structure includes one or more of: Ru, Os, Hs, or Fe.

[0090] At block 904, an interconnect is formed adjacent to the first structure of the magnetic junction. In various embodiments, this interconnect comprises AFM material (e.g., Neel spin orbit coupling material). In some embodiments, the AFM material is topological and in direct contact with the paramagnet of the first structure as described with reference to Figs. 7A-B. Referring back to Fig. 9, in some embodiments, the AFM material includes one of: Mn, Au, or As. In some embodiments, the AFM material is a quasi-two-dimensional triangular AFM including Ni(i-_X)M_xGa2S₄, where‘M’ includes one of: Mn, Fe, Co or Zn. In some embodiments, the method of forming the AFM comprises forming a stack of materials including a first material and a second material, wherein the first and second materials are different, and wherein the first and second materials include one or more of: Mn, Au, or As.

[0091] Fig. 10 illustrates a cross-section of a die layout having any of the devices of

Figs. 5-8 formed in metal 3 (M3) and metal 2 (M2) layer regions, according to some embodiments of the disclosure. Cross-section 1000 illustrates an active region having a transistor MN comprising diffusion region 1001, a gate terminal 1002, drain terminal 1004, and source terminal 1003. The source terminal 1003 is coupled to SL (source line) via poly or via, where the SL is formed on Metal 0 (M0). In some embodiments, the drain terminal 1004 is coupled to MOa (also metal 0) through via 1005. The drain terminal 1004 is coupled to AFM electrode 522 through Via 0-1 (e.g., via connecting metal 0 to metal 1 layers), metal 1 (Ml), Via 1-2 (e.g., via connecting metal 1 to metal 2 layers), and Metal 2 (M2).

[0092] In some embodiments, the magnetic junction (e.g., MTJ 1021 or spin valve) is formed in the metal 3 (M3) region. Here, MTJ 1021 (or spin valve) can be according to any one of MTJs described with reference to Figs. 5-8 having the free paramagnet structure which is coupled or biased Neel spin orbit interconnect 1022 (e.g., interconnect 522 or 722). Referring back to Fig. 10, in some embodiments, the in-plane free paramagnet layer of the magnetic junction (MTJ 1021 or spin valve) couples to Neel spin orbit interconnect 1022 (e.g., electrode 522). In some embodiments, the fixed in-plane magnet layer of magnetic junction couples to the bit-line (BL) via Neel spin orbit interconnect 1022 through Via 3-4 (e.g., via connecting metal 4 region to metal 4 (M4)). In this example, the bit-line is formed on M4.

[0093] In some embodiments, an n-type transistor MN is formed in the frontend of the die while the Neel spin orbit interconnect 1022 is located in the backend of the die. Here, the term“backend” generally refers to a section of a die which is opposite of a“frontend” and where an IC (integrated circuit) package couples to integrated circuit (IC) die bumps. For example, high level metal layers (e.g., metal layer 6 and above in a ten-metal stack die) and corresponding vias that are closer to a die package are considered part of the backend of the die. Conversely, the term“frontend” generally refers to a section of the die that includes the active region (e.g., where transistors are fabricated) and low-level metal layers and corresponding vias that are closer to the active region (e.g., metal layer 5 and below in the ten-metal stack die example). In some embodiments, the Neel spin orbit interconnect 1022 is located in the backend metal layers or via layers for example in Via 3. In some

embodiments, the electrical connectivity to the device is obtained in layers M0 and M4 or Ml and M5 or any set of two parallel interconnects. [0094] Fig. 11 illustrates a cross-section of a die layout having any of the devices of

Figs. 5-8 formed in metal 2 (M2) and metal 1 (Ml) layer regions, according to some embodiments of the disclosure. Compared to Fig. 10, here the magnetic junction (e.g., MTJ 1021 or spin valve) is formed in the metal 2 region and/or Via 1-2 region. In some embodiments, the Neel spin orbit interconnect 1022 is formed in the metal 1 region while magnetic via is formed in metal 1 or via 0- 1 region.

[0095] Fig. 12 illustrates a smart device or a computer system or a SoC (System-on-

Chip) with any of the devices of Figs. 5-8, according to some embodiments of the disclosure. For purposes of the embodiments, the transistors in various circuits and logic blocks described here are metal oxide semiconductor (MOS) transistors or their derivatives, where the MOS transistors include drain, source, gate, and bulk terminals. The transistors and/or the MOS transistor derivatives also include Tri-Gate and FinFET transistors, Gate All Around Cylindrical Transistors, Tunneling FET (TFET), Square Wire, or Rectangular Ribbon Transistors, ferroelectric FET (FeFETs), or other devices implementing transistor functionality like carbon nanotubes or spintronic devices. MOSFET symmetrical source and drain terminals i.e., are identical terminals and are interchangeably used here. A TFET device, on the other hand, has asymmetric Source and Drain terminals. Those skilled in the art will appreciate that other transistors, for example, Bi-polar junction transistors (BJT PNP/NPN), BiCMOS, CMOS, etc., may be used without departing from the scope of the disclosure.

[0096] Fig. 12 illustrates a block diagram of an embodiment of a mobile device in which flat surface interface connectors could be used. In some embodiments, computing device 1600 represents a mobile computing device, such as a computing tablet, a mobile phone or smart-phone, a wireless-enabled e-reader, or other wireless mobile device. It will be understood that certain components are shown generally, and not all components of such a device are shown in computing device 1600.

[0097] In some embodiments, computing device 1600 includes first processor 1610 with any of the devices of Figs. 5-8, according to some embodiments discussed. Other blocks of the computing device 1600 may also include any of the devices of Figs. 5-8, according to some embodiments. The various embodiments of the present disclosure may also comprise a network interface within 1670 such as a wireless interface so that a system embodiment may be incorporated into a wireless device, for example, cell phone or personal digital assistant. [0098] In some embodiments, processor 1610 (and/or processor 1690) can include one or more physical devices, such as microprocessors, application processors,

microcontrollers, programmable logic devices, or other processing means. The processing operations performed by processor 1610 include the execution of an operating platform or operating system on which applications and/or device functions are executed. The processing operations include operations related to I/O (input/output) with a human user or with other devices, operations related to power management, and/or operations related to connecting the computing device 1600 to another device. The processing operations may also include operations related to audio I/O and/or display I/O.

[0099] In some embodiments, computing device 1600 includes audio subsystem

1620, which represents hardware (e.g., audio hardware and audio circuits) and software (e.g., drivers, codecs) components associated with providing audio functions to the computing device. Audio functions can include speaker and/or headphone output, as well as microphone input. Devices for such functions can be integrated into computing device 1600, or connected to the computing device 1600. In one embodiment, a user interacts with the computing device 1600 by providing audio commands that are received and processed by processor 1610.

[00100] In some embodiments, computing device 1600 comprises display subsystem 1630. Display subsystem 1630 represents hardware (e.g., display devices) and software (e.g., drivers) components that provide a visual and/or tactile display for a user to interact with the computing device 1600. Display subsystem 1630 includes display interface 1632, which includes the particular screen or hardware device used to provide a display to a user. In one embodiment, display interface 1632 includes logic separate from processor 1610 to perform at least some processing related to the display. In one embodiment, display subsystem 1630 includes a touch screen (or touch pad) device that provides both output and input to a user.

[00101] In some embodiments, computing device 1600 comprises I/O controller 1640. I/O controller 1640 represents hardware devices and software components related to interaction with a user. I/O controller 1640 is operable to manage hardware that is part of audio subsystem 1620 and/or display subsystem 1630. Additionally, I/O controller 1640 illustrates a connection point for additional devices that connect to computing device 1600 through which a user might interact with the system. For example, devices that can be attached to the computing device 1600 might include microphone devices, speaker or stereo systems, video systems or other display devices, keyboard or keypad devices, or other I/O devices for use with specific applications such as card readers or other devices. [00102] As mentioned above, I/O controller 1640 can interact with audio subsystem 1620 and/or display subsystem 1630. For example, input through a microphone or other audio device can provide input or commands for one or more applications or functions of the computing device 1600. Additionally, audio output can be provided instead of, or in addition to display output. In another example, if display subsystem 1630 includes a touch screen, the display device also acts as an input device, which can be at least partially managed by I/O controller 1640. There can also be additional buttons or switches on the computing device 1600 to provide I/O functions managed by I/O controller 1640.

[00103] In some embodiments, I/O controller 1640 manages devices such as accelerometers, cameras, light sensors or other environmental sensors, or other hardware that can be included in the computing device 1600. The input can be part of direct user interaction, as well as providing environmental input to the system to influence its operations (such as filtering for noise, adjusting displays for brightness detection, applying a flash for a camera, or other features).

[00104] In some embodiments, computing device 1600 includes power management 1650 that manages battery power usage, charging of the battery, and features related to power saving operation. Memory subsystem 1660 includes memory devices for storing information in computing device 1600. Memory can include nonvolatile (state does not change if power to the memory device is interrupted) and/or volatile (state is indeterminate if power to the memory device is interrupted) memory devices. Memory subsystem 1660 can store application data, user data, music, photos, documents, or other data, as well as system data (whether long-term or temporary) related to the execution of the applications and functions of the computing device 1600.

[00105] Elements of embodiments are also provided as a machine-readable medium (e.g., memory 1660) for storing the computer-executable instructions (e.g., instructions to implement any other processes discussed herein). The machine-readable medium (e.g., memory 1660) may include, but is not limited to, flash memory, optical disks, CD-ROMs, DVD ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, phase change memory (PCM), or other types of machine-readable media suitable for storing electronic or computer- executable instructions. For example, embodiments of the disclosure may be downloaded as a computer program (e.g., BIOS) which may be transferred from a remote computer (e.g., a server) to a requesting computer (e.g., a client) by way of data signals via a communication link (e.g., a modem or network connection). [00106] In some embodiments, computing device 1600 comprises connectivity 1670. Connectivity 1670 includes hardware devices (e.g., wireless and/or wired connectors and communication hardware) and software components (e.g., drivers, protocol stacks) to enable the computing device 1600 to communicate with external devices. The computing device 1600 could be separate devices, such as other computing devices, wireless access points or base stations, as well as peripherals such as headsets, printers, or other devices.

[00107] Connectivity 1670 can include multiple different types of connectivity. To generalize, the computing device 1600 is illustrated with cellular connectivity 1672 and wireless connectivity 1674. Cellular connectivity 1672 refers generally to cellular network connectivity provided by wireless carriers, such as provided via GSM (global system for mobile communications) or variations or derivatives, CDMA (code division multiple access) or variations or derivatives, TDM (time division multiplexing) or variations or derivatives, or other cellular service standards. Wireless connectivity (or wireless interface) 1674 refers to wireless connectivity that is not cellular, and can include personal area networks (such as Bluetooth, Near Field, etc.), local area networks (such as Wi-Fi), and/or wide area networks (such as WiMax), or other wireless communication.

[00108] In some embodiments, computing device 1600 comprises peripheral connections 1680. Peripheral connections 1680 include hardware interfaces and connectors, as well as software components (e.g., drivers, protocol stacks) to make peripheral connections. It will be understood that the computing device 1600 could both be a peripheral device ("to" 1682) to other computing devices, as well as have peripheral devices ("from" 1684) connected to it. The computing device 1600 commonly has a "docking" connector to connect to other computing devices for purposes such as managing (e.g., downloading and/or uploading, changing, synchronizing) content on computing device 1600. Additionally, a docking connector can allow computing device 1600 to connect to certain peripherals that allow the computing device 1600 to control content output, for example, to audiovisual or other systems.

[00109] In addition to a proprietary docking connector or other proprietary connection hardware, the computing device 1600 can make peripheral connections 1680 via common or standards-based connectors. Common types can include a Universal Serial Bus (USB) connector (which can include any of a number of different hardware interfaces), DisplayPort including MiniDisplayPort (MDP), High Definition Multimedia Interface (HDMI), Firewire, or other types. [00110] Reference in the specification to "an embodiment," "one embodiment," "some embodiments," or "other embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments. The various appearances of "an embodiment," "one embodiment," or "some embodiments" are not necessarily all referring to the same embodiments. If the specification states a component, feature, structure, or characteristic "may," "might," or "could" be included, that particular component, feature, structure, or characteristic is not required to be included. If the specification or claim refers to "a" or "an" element, that does not mean there is only one of the elements. If the specification or claims refer to "an additional" element, that does not preclude there being more than one of the additional element.

[00111] Furthermore, the particular features, structures, functions, or characteristics may be combined in any suitable manner in one or more embodiments. For example, a first embodiment may be combined with a second embodiment anywhere the particular features, structures, functions, or characteristics associated with the two embodiments are not mutually exclusive.

[00112] While the disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations of such embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description. The embodiments of the disclosure are intended to embrace all such alternatives, modifications, and variations as to fall within the broad scope of the appended claims.

[00113] In addition, well known power/ground connections to integrated circuit (IC) chips and other components may or may not be shown within the presented figures, for simplicity of illustration and discussion, and so as not to obscure the disclosure. Further, arrangements may be shown in block diagram form in order to avoid obscuring the disclosure, and also in view of the fact that specifics with respect to implementation of such block diagram arrangements are highly dependent upon the platform within which the present disclosure is to be implemented (i.e., such specifics should be well within purview of one skilled in the art). Where specific details (e.g., circuits) are set forth in order to describe example embodiments of the disclosure, it should be apparent to one skilled in the art that the disclosure can be practiced without, or with variation of, these specific details. The description is thus to be regarded as illustrative instead of limiting. [00114] The following examples pertain to further embodiments. Specifics in the examples may be used anywhere in one or more embodiments. All optional features of the apparatus described herein may also be implemented with respect to a method or process.

[00115] Example 1. An apparatus comprising: a magnetic junction including: a stack of structures including: a first structure comprising a magnet; a second structure comprising one of a dielectric or metal; and a third structure comprising a magnet with in-plane magnetic anisotropy, wherein the third structure has an anisotropy axis along a plane of a device, and wherein the third structure is adjacent to the second structure such that the second structure is between the first and third structures; and an interconnect adjacent to the first structure of the magnetic junction, wherein the interconnect comprises an antiferromagnetic (AFM) material.

[00116] Example 2. The apparatus of example 1, wherein the magnet of the first structure comprises a paramagnet which has unfixed in-plane magnetic anisotropy, and wherein the paramagnet has an anisotropy axis along the plane of the device.

[00117] Example 3. The apparatus of example 1, wherein the magnetic junction comprises: a fourth structure between the first and second structures, wherein the fourth structure includes one or more of: Ru, Os, Hs, or Fe.

[00118] Example 4. The apparatus according to any one of examples 1 to 3, wherein the magnetic junction comprises a fifth structure between the second and third structures, wherein the fifth structure includes one or more of: Ru, Os, Hs, or Fe.

[00119] Example 5. The apparatus according to any one of examples 1 to 3, wherein the AFM material is topological and in direct contact with the paramagnet of the first structure.

[00120] Example 6. The apparatus according to any one of examples 1 to 3, wherein the AFM material includes one of: Mn, Au, or As.

[00121] Example 7. The apparatus according to any one of examples 1 to 3, wherein the AFM comprises a stack of materials including a first material and a second material, wherein the first and second materials are different, and wherein the first and second materials include one or more of: Mn, Au, or As.

[00122] Example 8. The apparatus according to any one of examples 1 to 3, wherein the AFM material is a quasi-two-dimensional triangular AFM including Ni(i-_X)M_xGa2S₄, where‘M’ includes one of: Mn, Fe, Co or Zn.

[00123] Example 9. The apparatus according to any one of preceding examples, wherein the magnetic junction is one of a spin valve or a magnetic tunneling junction (MTJ). [00124] Example 10. The apparatus according to any one of preceding examples, wherein the magnet of the first structure includes one or more of: Pt, Pd, W, Ce, Al, Li, Mg, Na, Cr, Co, Dy, O, Er, Eu, Eu, Gd, Fe, Nd, K, Pr, Sm, Tb, Tm, or V.

[00125] Example 11. The apparatus according to any one of preceding examples, wherein the magnet of the first structure comprises dopants which include one or more of:

Ce, Cr, Mn, Nb, Mo, Tc, Re, Nd, Gd, Tb, Dy, Ho, Er, Tm, or Yb.

[00126] Example 12. The apparatus according to any one of the preceding examples, wherein the magnet of the third structure includes one or more of: Co, Fe, Ge, or Ga or a Heusler alloy.

[00127] Example 13. The apparatus of example 11, wherein the Heusler alloy includes one or more of Co, Cu, Fe, Ga, Ge, In, Mn, Al, In, Sb, Si, Sn, Ni, Pd, Ru, or V.

[00128] Example 14. A system comprising: a memory; a processor coupled to the memory, the processor having a spin wave switch, which comprises an apparatus according to any one of apparatus examples 1 to 13; and a wireless interface to allow the processor to communicate with another device.

[00129] Example 15. An apparatus comprising: a magnetic junction; and an interconnect adjacent to the magnetic junction, wherein the interconnect comprises a material exhibiting Neel spin orbit coupling.

[00130] Example 16. The apparatus of example 15, wherein the magnetic junction comprises: a stack of structures including: a first structure comprising a magnet; a second structure comprising one of a dielectric or metal; and a third structure comprising a magnet with fixed in-plane magnetic anisotropy, wherein the third structure has an anisotropy axis along a plane of a device, and wherein the third structure is adjacent to the second structure such that the second structure is between the first and third structures.

[00131] Example 17. The apparatus of example 16, wherein the material of the interconnect comprises an antiferromagnetic (AFM) material.

[00132] Example 18. The apparatus of example 17 according to any one of claims 2 to 13.

[00133] Example 19. A system comprising: a memory; a processor coupled to the memory, the processor having a spin wave switch, which comprises an apparatus according to any one of apparatus examples 14 to 17; and a wireless interface to allow the processor to communicate with another device.

[00134] Example 20. A method comprising: forming a magnetic junction including: forming a stack of structures including: forming a first structure comprising a paramagnet; forming a second structure comprising one of a dielectric or metal; and forming a third structure comprising forming a magnet with fixed in-plane magnetic anisotropy, wherein the third structure has an anisotropy axis along a plane of a device, and wherein the third structure is adjacent to the second structure such that the second structure is between the first and third structures; and forming an interconnect adjacent to the first structure of the magnetic junction, wherein forming the interconnect comprises forming an antiferromagnetic (AFM) material.

[00135] Example 21. The method of example 20, wherein the paramagnet has unfixed in-plane magnetic anisotropy, wherein the paramagnet has an anisotropy axis along a plane of a device.

[00136] Example 22. The method of example 20, wherein forming the magnetic junction comprises: forming a fourth structure between the first and second structures, wherein the fourth structure includes one or more of: Ru, Os, Hs, or Fe.

[00137] Example 23. The method according to any one of examples 20 to 22, wherein forming the magnetic junction comprises forming a fifth structure between the second and third structures, wherein the fifth structure includes one or more of: Ru, Os, Hs, or Fe.

[00138] Example 24. The method according to any one of examples 20 to 22, wherein the AFM material is topological and in direct contact with the paramagnet of the first structure.

[00139] Example 25. The method according to any one of examples 19 to 21, wherein the AFM material includes one of: Mn, Au, or As.

[00140] Example 26. The method according to any one of examples 19 to 21, wherein the AFM material is a quasi-two-dimensional triangular AFM including Ni(i-_X)MxGa2S₄, where‘M’ includes one of: Mn, Fe, Co or Zn.

[00141] Example 27. The method according to any one of preceding method examples, wherein the magnetic junction is one of a spin valve or a magnetic tunneling junction (MTJ).

[00142] Example 28. The method according to any one of preceding method examples, wherein the paramagnet includes one or more of: Pt, Pd, W, Ce, Al, Li, Mg, Na,

Cr, Co, Dy, O, Er, Eu, Eu, Gd, Fe, Nd, K, Pr, Sm, Tb, Tm, or V.

[00143] Example 29. The method according to any one of preceding method examples, wherein the paramagnet comprises dopants which include one or more of: Ce, Cr, Mn, Nb, Mo, Tc, Re, Nd, Gd, Tb, Dy, Ho, Er, Tm, or Yb. [00144] Example 30. The method according to any one of the preceding method examples, wherein the magnet of the third structure includes one or more of: Co, Fe, Ge, or Ga or a Heusler alloy.

[00145] Example 31. The method of example 20, wherein the Heusler alloy includes one or more of: Co, Cu, Fe, Ga, Ge, In, Mn, Al, In, Sb, Si, Sn, Ni, Pd, Ru, or V.

[00146] Example 32. The method according to any one of examples 19 to 21, wherein forming the AFM comprises forming a stack of materials including a first material and a second material, wherein the first and second materials are different, and wherein the first and second materials include one or more of: Mn, Au, or As.

[00147] Example 33. A method comprising: forming a magnetic junction; and forming an interconnect adjacent to the magnetic junction, wherein the interconnect comprises a material exhibiting Neel spin orbit coupling.

[00148] Example 34. The method of example 33, wherein forming the magnetic junction comprises: forming a stack of structures including: forming a first structure comprising a magnet; forming a second structure comprising one of a dielectric or metal; and forming a third structure comprising a magnet with fixed in-plane magnetic anisotropy, wherein the third structure has an anisotropy axis along a plane of a device, and wherein the third structure is adjacent to the second structure such that the second structure is between the first and third structures.

[00149] Example 35. The method of example 34, wherein the material of the interconnect comprises an antiferromagnetic (AFM) material.

[00150] An abstract is provided that will allow the reader to ascertain the nature and gist of the technical disclosure. The abstract is submitted with the understanding that it will not be used to limit the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.

Claims

CLAIMS We claim:

1. An apparatus comprising:

a magnetic junction including:

a stack of structures including:

a first structure comprising a magnet;

a second structure comprising one of a dielectric or metal; and a third structure comprising a magnet with in-plane magnetic anisotropy relative to an x-y plane of a device, and wherein the third structure is adjacent to the second structure such that the second structure is between the first and third structures; and

an interconnect adjacent to the first structure of the magnetic junction, wherein the interconnect comprises an antiferromagnetic (AFM) material.

2. The apparatus of claim 1, wherein the magnet of the first structure comprises a

paramagnet which has unfixed in-plane magnetic anisotropy relative to the x-y plane of the device.

3. The apparatus of claim 1, wherein the magnetic junction comprises: a fourth structure between the first and second structures, wherein the fourth structure includes one or more of: Ru, Os, Hs, or Fe.

4. The apparatus according to any one of claims 1 to 3, wherein the magnetic junction

comprises a fifth structure between the second and third structures, wherein the fifth structure includes one or more of: Ru, Os, Hs, or Fe.

5. The apparatus according to any one of claims 1 to 3, wherein the AFM material is

topological and in direct contact with the paramagnet of the first structure.

6. The apparatus according to any one of claims 1 to 3, wherein the AFM material includes one of: Mn, Au, or As.

7. The apparatus according to any one of claims 1 to 3, wherein the AFM comprises a stack of materials including a first material and a second material, wherein the first and second materials are different, and wherein the first and second materials include one or more of: Mn, Au, or As.

8. The apparatus according to any one of claims 1 to 3, wherein the AFM material is a

quasi-two-dimensional triangular AFM including Ni(i-_X)M_xGa2S₄, where‘M’ includes one of: Mn, Fe, Co or Zn.

9. The apparatus according to any one of preceding claims, wherein the magnetic junction is one of a spin valve or a magnetic tunneling junction (MTJ).

10. The apparatus according to any one of preceding claims, wherein the magnet of the first structure includes one or more of: Pt, Pd, W, Ce, Al, Li, Mg, Na, Cr, Co, Dy, O, Er, Eu, Eu, Gd, Fe, Nd, K, Pr, Sm, Tb, Tm, or V.

11. The apparatus according to any one of preceding claims, wherein the magnet of the first structure comprises dopants which include one or more of: Ce, Cr, Mn, Nb, Mo, Tc, Re, Nd, Gd, Tb, Dy, Ho, Er, Tm, or Yb.

12. The apparatus according to any one of the preceding claims, wherein the magnet of the third structure includes one or more of: Co, Fe, Ge, or Ga or a Heusler alloy.

13. The apparatus of claim 11, wherein the Heusler alloy includes one or more of Co, Cu, Fe, Ga, Ge, In, Mn, Al, In, Sb, Si, Sn, Ni, Pd, Ru, or V.

14. A system comprising: a memory; a processor coupled to the memory, the processor

having a spin wave switch, which comprises an apparatus according to any one of apparatus claims 1 to 13; and a wireless interface to allow the processor to communicate with another device.

15. An apparatus comprising:

a magnetic junction; and

an interconnect adjacent to the magnetic junction, wherein the interconnect comprises a Neel spin orbit material.

16. The apparatus of claim 15, wherein the magnetic junction comprises:

a stack of structures including: a first structure comprising a magnet;

a second structure comprising one of a dielectric or metal; and a third structure comprising a magnet with fixed in-plane magnetic anisotropy, and wherein the third structure is adjacent to the second structure such that the second structure is between the first and third structures.

17. The apparatus of claim 16, wherein the material of the interconnect comprises an

antiferromagnetic (AFM) material.

18. The apparatus of claim 17 according to any one of claims 2 to 13.

19. A system comprising: a memory; a processor coupled to the memory, the processor

having a spin wave switch, which comprises an apparatus according to any one of apparatus claims 14 to 17; and a wireless interface to allow the processor to communicate with another device.

20. A method comprising:

forming a magnetic junction including:

forming a stack of structures including:

forming a first structure comprising a paramagnet;

forming a second structure comprising one of a dielectric or metal; and forming a third structure comprising forming a magnet with fixed in plane magnetic anisotropy relative to an x-y plane of a device, and wherein the third structure is adjacent to the second structure such that the second structure is between the first and third structures; and

forming an interconnect adjacent to the first structure of the magnetic junction, wherein forming the interconnect comprises forming an antiferromagnetic (AFM) material.

21. The method of claim 20, wherein the paramagnet has unfixed in-plane magnetic

anisotropy relative to the x-y plane of the device.

22. The method of claim 20, wherein forming the magnetic junction comprises: forming a fourth structure between the first and second structures, wherein the fourth structure includes one or more of: Ru, Os, Hs, or Fe.

23. The method according to any one of claims 20 to 22, wherein forming the magnetic junction comprises forming a fifth structure between the second and third structures, wherein the fifth structure includes one or more of: Ru, Os, Hs, or Fe.

24. The method according to any one of claims 20 to 22, wherein the AFM material is

topological and in direct contact with the paramagnet of the first structure.

25. The method according to any one of claims 19 to 21, wherein the AFM material includes one of: Mn, Au, or As, or wherein the AFM material is a quasi-two-dimensional triangular AFM including Ni(i-_X)M_xGa2S₄, where‘M’ includes one of: Mn, Fe, Co or Zn.