HK1075125A - Magnetic element with dual magnetic states and fabricating method thereof - Google Patents

Description

Magnetic element with dual magnetic states and method of making the same

The application date of the application is divisional application of Chinese patent application 00136605.X of 12 months and 15 days in 2000.

Technical Field

The present invention relates to magnetic elements for information storage and/or readout and methods of making the same, and more particularly to a dual magnetic state magnetic element and a method of making the same.

Background

The following co-pending applications, which are related to the present application and belong to the same assignee, are hereby incorporated by reference: motorola, Inc. CR 97-133 AND U.S. Ser. No. 09/144,686, filed on 31.8.1998, entitled "MAGNETIC RANDOM Access memory AND METHOD of manufacturing THEREOF" ("MAGNETIC RANDOM Access memory AND manufacturing METHOD THEREOF"); a Motorola application No. CR 97-158 and us serial No. 08/986,764, filed on 8.12.1997 under the name "magnetic film pattern formation method" ("processes OF PATTERNING MAGNETIC FILMS"); motorola, Inc. CR 99-001 AND U.S. Ser. No. 09/356,864, filed on 19.7.1999, entitled "magnetic element with improved magnetic field RESPONSE AND METHOD of making the same" ("MAGNETIC ELEMENT WITH IMPROVEDFIELD RESPONSE AND FABRICATING METHOD THEREOF"); also, U.S. patent No. 5,768,181, assigned to the same assignee hereof, was incorporated by reference, and issued at 16.6.1998, entitled "multilayer magnetic device with thermal and conductive layers" ("MAGNETIC DEVICE HAVING MULTI-LAYERWITH INSULATING AND CONDUCTIVE LAYERS").

In general, a magnetic element, such as a magnetic tunnel junction memory element, structurally contains a number of ferromagnetic layers separated by a nonmagnetic spacer layer. Information may be stored in the magnetic layer in the direction of the magnetization vector. For example, the magnetization vector in another magnetic layer is free to commutate between the same and opposite directions, so-called "parallel" and "anti-parallel" states, and accordingly, the magnetization vector in a magnetic layer is fixed or locked within the range of action of this magnetic field. The magnetic memory element exhibits two different resistances corresponding to the parallel and anti-parallel states. When the magnetization vectors in the two magnetic layers are directed substantially in the same direction and in opposite directions, a minimum and a maximum of the resistance occur, respectively. And the detection of the impedance transformation enables the storage of information in the magnetic memory element by means of a device such as an MRAM (magnetic random access memory). The difference between the maximum and minimum impedance values divided by the minimum impedance value is known as the reluctance ratio (MR).

An MRAM device integrates magnetic elements, particularly a number of magnetic memory elements, as well as other circuits, such as magnetic memory element control circuits, comparators for detecting the state of a magnetic memory element, input/output circuits, and the like. These lines are fabricated using a CMOC (complementary metal oxide semiconductor) process to reduce the power consumption of the device.

In addition, structurally, the magnetic elements contain many thin layers, some of which are tens of angstroms thick. The impedance response to magnetic fields of the magnetic elements is constrained by the surface structure of these thin layers. In order for a magnetic element to operate as a memory cell, it has at least two resistance states when in an idle state or when no external magnetic field is applied to it. This requirement for the magnetic element is equivalent to having an intermediate impedance with respect to the magnetic field response, which must be corrected for the presence of topological positive and pinhole couplings to form the intermediate impedance.

In typical MTJ (magnetic tunnel junction) magnetic element fabrication, such as MRAM memory element fabrication, there is a metal film that is formed by sputter deposition, evaporation, or epitaxial processes, whose film surface is not truly planar but exhibits surface or interface ripples. This waviness of the surface and/or ferromagnetic interlayer interface is responsible for the magnetic coupling that exists between the free ferromagnetic layer and other ferromagnetic layers, such as the fixed or pinned layers, which is known as topological or Neel's orange-peel coupling. This coupling is generally undesirable in magnetic elements because it causes a shift in the response of the free layer to the external magnetic field. In addition, in the constitution of a commonly used spin valve magnetic element, electron exchange coupling also exists. To compensate for this type of coupling, as well as other coupling effects found in MTJ and spin valve elements, compensation must be made to produce an intermediate impedance so that the device can operate in the two states.

Also, there are generally two shifts in the magnetic field reversal of an MRAM memory cell. The first is ferromagnetic coupling or positive coupling, as previously described, which is caused by topology dependent magnetostatic coupling and results in only a low impedance memory state in the absence of an external magnetic field. Such a memory cell is virtually inoperable. To make the memory function, at least two memory states are provided in a zero magnetic field. Another commutation offset of the cell may be referred to as antiferromagnetic coupling or negative coupling. It is caused by magnetostatic coupling at the ends of the memory cells having an aspect ratio equal to or greater than 1. Its effect is that a high impedance memory state occurs when there is zero external magnetic field. Such a memory does not work without an applied read-in magnetic field. Preferably, reading should be performed without applying a magnetic field caused by current pulses to save power consumption and achieve high speed.

Therefore, it is necessary to fabricate a device with bit end static fringing fields (bit end magnetic fringing fields) at the ends of the memory cell that will cancel out the full positive coupling of this structure, thereby achieving a dual magnetic state with zero external magnetic field.

The ferromagnetic coupling strength is said to be proportional to the surface magnetic charge density and is determined as the inverse of the interlayer thickness index value. There is a U.S. patent No. 5,764,567, issued 6/9 of 1998, entitled "MAGNETIC TUNNEL JUNCTION device with non-ferromagnetic interface layer for improved MAGNETIC field RESPONSE" ("MAGNETIC TUNNEL JUNCTION device with non-ferromagnetic JUNCTION layer INTERFACE LAYER for ferromagnetic cluster MAGNETIC FIELD RESPONSE"), in which: a non-magnetic copper layer is added to the position, close to the alumina tunnel barrier layer, of the magnetic tunnel junction structure, so that the distance between magnetic layers can be increased, and ferromagnetic orange peel coupling or topological coupling can be reduced. However, the additional copper layer may lower the MR of the tunnel junction, thereby deteriorating the device performance. In addition, the inclusion of copper layers also adds complexity to the metal etching process.

Disclosure of Invention

It is therefore an object of the present invention to provide an improved magnetic element having a centered impedance response curve with respect to an applied magnetic field, thereby enabling two-state operation.

It is another object of the present invention to provide an improved magnetic element that compensates for the presence of ferromagnetic coupling, particularly topologically-induced ferromagnetic coupling or exchange coupling.

It is a further object of the present invention to provide a magnetic element wherein the cell end demagnetizing fields (bit end demagnetizing fields) will cancel the total positive coupling of such a structure to achieve a dual magnetic state at zero external magnetic field.

It is a further object of the present invention to provide a method of manufacturing a magnetic element having a centered resistance to magnetic field response, thereby enabling two-state operation.

It is a further object of the present invention to provide a method of manufacturing a magnetic element which has a centered resistance to magnetic field response and which can be modified to be suitable for mass production.

All of these needs and others are basically met by providing a magnetic element that contains a plurality of thin film layers in which the cell end demagnetizing field offsets all positive coupling of the structure to achieve a dual magnetic state in the absence of an external magnetic field. In addition, a method of fabricating a magnetic element from a plurality of thin film layers is also disclosed wherein the cell end demagnetizing fields on each thin film layer will cancel the full positive coupling of such a structure to achieve a dual magnetic state in the absence of an external magnetic field.

Drawings

FIGS. 1-5 show cross-sectional views of a plurality of magnetic elements, all having the improved magnetic field response of the present invention;

FIG. 6 illustrates experimental results of topologically coupled magnetic fields and demagnetization fields calculated according to the present invention relative to a thickness of a fixed magnetic layer;

figure 7 illustrates the magnetic poles of the metal film layers of the magnetic element of the present invention.

In the description, like elements in the various figures used to describe the invention are identified with like reference numerals.

Detailed Description

FIGS. 1 and 2 illustrate in cross-sectional views the structure of two embodiments of MTJ magnetic elements according to the invention. In particular, a patterned complete magnetic element structure 10 is illustrated in FIG. 1. It contains a synthetic antiferromagnetic structure 11. This structure comprises a substrate 12, a bottom electrode multilayer stack 14, a backing layer 16 comprising alumina, and a top electrode multilayer stack 18. Both the bottom electrode multilayer stack 14 and the top electrode multilayer stack 18 contain ferromagnetic layers. The bottom electrode layer 14 is formed on a metal lead 13, and the metal lead 13 is formed on the substrate 12. The bottom electrode layer 14 comprises a plurality of bottom layers 20 deposited on the bottom metal lead 13 and which function as seed and template layers, and further comprises an antiferromagnetic pinning material layer 22, a pinned ferromagnetic layer 24, a ruthenium interlayer 26, and a fixed ferromagnetic layer 28 formed thereon and exchange coupled to the underlying antiferromagnetic pinning layer 22.

Underlayer 20 is typically formed from tantalum and ruthenium (Ta/Ru). They act as orientation mounts for the antiferromagnetic pinning layer 22. The antiferromagnetic pinning layer 22 is typically composed of iridium manganese (IrMn) or platinum manganese (PtMn).

The pinned ferromagnetic layer 24 is pinned, its magnetic moment is exchange coupled to the pinned layer 22 so that its magnetic moment remains untwisted when a sufficiently large external magnetic field is present to flip the free magnetic layer 30. The ferromagnetic layer 24 is typically formed of an alloy of one or more of nickel (Ni), iron (Fe), and cobalt (Co). Second, interlayer 26 is typically formed of ruthenium and functions to induce antiferromagnetic exchange coupling between pinned ferromagnetic layer 24 and fixed ferromagnetic layer 28. Finally, a fixed ferromagnetic layer 28 is formed on the upper surface of the ruthenium interlayer 26. Fixed ferromagnetic layer 28 is fixed or pinned so that its magnetic moment is prevented from flipping in the presence of an external magnetic field large enough to flip free ferromagnetic layer 30.

The top electrode stack 18 contains a free ferromagnetic layer 30 and a protective layer 32. The magnetic moment of free ferromagnetic layer 30 is not fixed, or pinned by exchange coupling, and is free to switch between the two states in the presence of an external magnetic field. The free ferromagnetic layer 30 is typically formed from a nickel-iron alloy (NiFe).

Thickness t of the fixed ferromagnetic layer 28₁Generally, the content is in the range of 3 to 100 *. Thickness t of pinned ferromagnetic layer 24₂Meaning, typically less than 100 *. The thickness t of the cushion layer 16₃Meaning, typically less than 50 *. This is for a magnetic tunnel junction structure or a spin valve type film with a copper liner. In this particular embodiment, to compensate for the positive coupling across the spacer layer 16, the thickness of the fixed ferromagnetic layer 28 is made larger than that of the pinned ferromagnetic layer 24, i.e., t₁＞t₂. Should beIt is clear that: inverted or flip-chip configurations are contemplated in the disclosure herein. In particular, it is contemplated that the disclosed magnetic element may be formed by including a top fixed or pinned layer, thus described as a top pinned structure.

All magnetic layers may be a single magnetic material or a composite magnetic layer made of multiple magnetic layers, adjacent to each other to fine tune their magnetic parameters, such as switching field, reluctance, etc. In this embodiment, the pinned ferromagnetic layer 28 has M₁And T₁Two parameters, M-magnetization and T-thickness, the pinned ferromagnetic layer 24 has M₂And T₂Two parameters, the free ferromagnetic layer 30 has M₃And T₃Two parameters.

To compensate for the positive topological coupling that exists between the fixed ferromagnetic layer 28 and the free ferromagnetic layer 30, the product M₁T₁Should be greater than M₂T₂. Can make T₁＞T₂，M₁＝M₂Or let T be₁＝T₂，M₁＞M₂Or let T be₁＞T₂，M₁＞M₂To achieve this. Adjusting M₁And T₁And M is₂T₂The difference between the two allows the positive coupling to be completely eliminated. When M is₁T₁＞M₂T₂There will be uncompensated magnetic poles or charges at the ends of the fixed ferromagnetic layer 28. In a high density memory cell having a length/width ratio of 1 or more, the magnetostatic coupling existing between the free ferromagnetic layer 30 and the ends of the fixed and pinned ferromagnetic layers is diamagnetic, forming a closed magnetic flux. This antiferromagnetic coupling may be through M₁T₁And M₂T₂The difference is adjusted to completely eliminate the positive coupling.

FIG. 2 is an alternative embodiment of a patterned complete magnetic element structure, see FIG. 10 ', which contains a synthetic antiferromagnetic structure 11'. It should be noted that: all parts of the first and second embodiments that are identical are labeled with the same reference numerals, with an apostrophe added to indicate the different embodiments. Like the structure shown in fig. 1, this structure comprises a substrate 12 ', a bottom electrode multilayer 14', a backing layer 16 ', and a top electrode multilayer 18'. Both the bottom electrode multilayer stack 14 'and the top electrode multilayer stack 18' contain ferromagnetic layers, substantially the same as stacks 14 and 18 in fig. 1. The bottom electrode layer 14 'is formed on the metal lead 13', and the metal lead 13 'is formed on the substrate 12'; the electrode layer 14 'also contains a plurality of bottom layers 20', the bottom layers 20 'including a first seed layer 21 deposited on the metal leads 13' and a template layer 23. The electrode layer 14 'also has a layer of antiferromagnetic material 22', a pinned ferromagnetic layer 24 'formed thereon and exchange coupled with the underlying antiferromagnetic layer 22', a coupling interlayer 26 ', and a fixed ferromagnetic layer 28' antiferromagnetically coupled with the pinned layer. The ferromagnetic layers 24 'and 28' are pinned or fixed and their magnetic moments are prevented from flipping in the presence of an external magnetic field. The top electrode stack 18 ' contains a free ferromagnetic layer 30 ' and a protective layer 32 '. The magnetic moment of free ferromagnetic layer 30' is not fixed or pinned by exchange coupling, and its magnetic moment is free to switch between the two states in the presence of an external magnetic field.

T for fixing the thickness of the ferromagnetic layer 28₁And (4) showing. Thickness T of pinned ferromagnetic layer 24₂And (4) showing. In this particular embodiment, to compensate for the positive coupling across the spacer layer 16 ', the fixed ferromagnetic layer 28' is formed to have a thickness greater than that of the pinned ferromagnetic layer 24, i.e., T₁＞T₂. It should be understood that: inverted or flip-chip configurations are contemplated in the disclosure herein. In particular, it is contemplated that the disclosed magnetic element having a SAF (synthetic antiferromagnetic) structure may be formed with a top fixed or pinned layer, thus described as a top pinned structure.

The fabrication of this embodiment includes two etching processes. First, all layers are etched to define the magnetic device 10 ', and then the protective layer 32 ' and the free ferromagnetic layer 30 ' are etched to define the offset 40. Specifically, the layers below the free ferromagnetic layer 30 'are larger than the free ferromagnetic layer 30' by an offset 40. This etching of the device 10 'ensures that a short across the pad layer 16' is avoided.

Referring now to fig. 3, a simplified cross-sectional view of another embodiment of a magnetic device of the present invention is shown. Specifically, a device 50 is shown that is substantially the same as the device 10 of FIG. 1, except that in this particular embodiment, the magnetic element 50 does not include a coupling interlayer and a fixed ferromagnetic layer. Like the structure depicted in fig. 1, the structure includes a substrate 52, a bottom electrode multilayer stack 54, a liner layer 56, and a top electrode multilayer stack 58. Both bottom electrode multilayer stack 54 and top electrode multilayer stack 58 have ferromagnetic layers, substantially the same as stacks 14 and 18 of fig. 1. The bottom electrode layer 54 is formed on the metal wiring 53, and the metal wiring 53 is formed on the substrate 52; the electrode layer 54 contains a plurality of underlying layers 60 including a first seed layer 61 deposited over the metal leads 53 and a template layer 63. The bottom electrode multilayer stack 54 also contains a pinned ferromagnetic layer 64. The pinned ferromagnetic layer 64 is fixed or pinned and its magnetic moment is prevented from flipping in the presence of an external magnetic field below a certain strength. The top electrode stack 58 contains a free ferromagnetic layer 70 and a protective layer 72. The magnetic moment of free ferromagnetic layer 70 is not fixed or pinned by exchange coupling, and is free to switch between the two states in the presence of an external magnetic field above a certain magnitude.

Essentially the same as the embodiment described in fig. 2, device 50 may contain an offset 74, see fig. 4. It should be understood that: all parts of the embodiment of figure 3 that are identical to the embodiment of figure 4 are given the same reference numerals with an apostrophe added to indicate the different embodiments.

In the embodiment depicted in FIG. 4, the offset 74 provides the effect of reducing the demagnetization field from the pinned ferromagnetic layer 64 'to the free ferromagnetic layer 70', thereby eliminating the positive coupling between the pinned ferromagnetic layer 64 'and the free ferromagnetic layer 70'. It should be understood that: inverted or flip-chip configurations are contemplated in the disclosure herein. In particular, it is contemplated that the disclosed magnetic element may be formed by including a top fixed or pinned layer, thus described as a top pinned structure.

Referring again to fig. 4, the fabrication of this embodiment includes two etching processes. First, all layers are etched to define the magnetic device 50'. The protective layer 72 'and the free ferromagnetic layer 70' are then etched to determine the offset 74. Specifically, the layers below the free ferromagnetic layer 70 'are larger than the free ferromagnetic layer 70' by an offset 74. This etching of device 50 'ensures that a short across pad layer 56' is avoided.

Referring now to fig. 5, a simplified cross-sectional view of another embodiment of a magnetic element of the present invention is shown. Specifically, a magnetic element 80 is shown that is devoid of a coupling interlayer and a fixed ferromagnetic layer. As in the structure suggested in fig. 4, it contains a substrate 82, a bottom electrode multilayer stack 84, a first liner layer 86, a second liner layer or tunnel barrier layer 88 and a top electrode multilayer stack 90. Both bottom electrode multilayer stack 84 and top electrode multilayer stack 90 include ferromagnetic layers, substantially the same as stacks 14 and 18 of fig. 1. The bottom electrode multilayer stack 84 is formed on a bottom metal lead 83, and the lead 83 is formed on the substrate 82; the bottom electrode multilayer stack 84 also contains a number of bottom layers including a first seed layer 81 and an optional template layer 85 deposited on a bottom metal lead 83. The bottom electrode multilayer stack 84 also contains a ferromagnetic layer 92. The ferromagnetic layer 92 is fixed or pinned and its magnetic moment is prevented from flipping in the presence of an external magnetic field below a certain strength. The bottom electrode multilayer stack 84 additionally contains a spacer layer 86 and a free ferromagnetic layer 94. The magnetic moment of free ferromagnetic layer 94 is not fixed or pinned by exchange coupling and is free to switch between the two states in the presence of an external magnetic field greater than a certain magnitude. The top electrode stack 90 contains a second fixed ferromagnetic layer 96 and a protective layer 98. The ferromagnetic layers 92 and 96 have an antiparallel alignment due to end-magneto static coupling.

Essentially the same as the embodiment described in fig. 4, device 80 may optionally contain an offset 100, as shown in fig. 5. The offset 100 provides the effect of reducing the demagnetization field from at least one of the ferromagnetic layers 92 or 96 to the free ferromagnetic layer 94, thereby eliminating positive coupling between the ferromagnetic layer 92 or 96 and the free ferromagnetic layer 96. It should be understood that: the disclosure herein contemplates an inverted or flip-chip configuration.

The fabrication of this embodiment includes two etching steps when there is an offset of 100. First, the layers are etched to define the magnetic device 80, and then the protective layer 98 and the ferromagnetic layer 96 are etched to define the offset 100. Specifically, the layers below the ferromagnetic layer 96 are offset from the pinned ferromagnetic layer 96. This etching of device 80 ensures that a short across pad layer 88 is avoided.

Referring now to FIG. 6, a topological coupled magnetic field (H) of the thickness of a fixed ferromagnetic layer 28, such as in FIG. 1, relative to such a magnetic element is illustrated_cp1) And the effect of a cell end demagnetizing field or negative magnetic field. As shown, the demagnetizing field will decrease as the offset of the device layers illustrated in fig. 2 and 4 increases. An offset of less than 3000 * will induce a large negative or demagnetizing field. Magnetic elements are commonly used in information storage and/or reading devices which must maintain a low switching field using thin free layers, however, when devices are designed with these thin free layers, the topologically coupled magnetic field H will be generated_cp1And (4) enhancing. Accordingly, in order to compensate or eliminate such topological magnetic field H_cp1Adjustments may be made to the remaining structure of the magnetic elements disclosed herein to utilize the demagnetizing field to compensate for or cancel such positively coupled magnetic fields.

Referring to FIG. 7, it is illustrated that the coupling magnetic field is reduced by adjusting the thickness of the magnetic layer, such as adjusting the layer thickness of the fixed layer 28 relative to the pinned layer 24 in FIG. 1. As shown therein, when the layer thickness of the fixed layer 28 is increased to be larger than that of the pinned layer 24, a positive coupling magnetic field H exists_cp1It is compensated for. The presence of the positive end-pole and the opposite negative end-pole may eliminate various positive couplings such as topology, pinholes, and positron exchanges. Accordingly, as shown in FIG. 7, a magnetic element substantially identical to the magnetic element 10 of FIG. 1, which in addition to the free layer 30, has a fixed layer 28 with a greater layer thickness than the pinned layer 24, provides a difference between the layers 28 and 30 to cancel the positive coupling and provide a centered resistance with respect to the magnetic field response and a balancer capable of operating in a binary stateAnd (3) a component.

Referring more specifically to FIG. 7, a magnetic end pole is formed between layers 24 and 28. Increasing the thickness of the fixed layer 28 to be greater than that of the pinned layer 24 allows compensation for positive coupling in the magnetic element 10.

As will be disclosed below: the use of non-magnetic seed and template layers, such as layers 61 and 63 in FIG. 3, will result in a reduction of the magnetic field responsive coupling without the inclusion of SAF structures. The template layer does not impart a magnetic moment to the structure, and thus, the only end magnetostatic coupling is a result of the thin pinned layer in the structure. This can be adjusted accordingly to eliminate its coupling strength to enable the device to operate in a binary state. When the template layer 63 is nonmagnetic and there is no SAF structure, there is negative magnetostatic coupling due to the poles at the ends of the patterned shape, and thus, the positive coupling can be controlled by the thickness of the pinned layer 64 relative to the free layer 70. The thickness of the pinned layer 64 may be selected to cancel the magnetostatic coupling, giving a centered loop. Thus, by reducing the thickness of the pinned layer 64 to be less than the pinned layer 70, a counteracting effect of positive coupling may be achieved in the magnetic element 50.

Referring again to fig. 7, the structure of the magnetic element 10 of fig. 1 is shown showing the magnetic poles where the cell end static magnetic demagnetizing field eliminates all positive coupling of the structure to achieve a dual magnetic state at zero external magnetic field.

Thus, a magnetic element capable of operating in a two-state and method of construction thereof is disclosed wherein magnetic coupling is eliminated, or compensated, based on the thickness of the magnetic layers or the product of magnetization and thickness relative to each other. The techniques may be applied to devices that use patterned magnetic elements, such as magnetic sensors, magnetic recording heads, magnetic recording media, and others. Accordingly, these illustrations are also covered by the disclosure.

Claims (7)

1. A magnetic element (10, 10 ', 50, 50', 80) characterized by: a plurality of thin film layers, wherein the end of the cell static demagnetizing fields (bit end-static demagnetizing fields) cancel all positive coupling of the structure to achieve dual magnetic states at zero external magnetic field.

2. The magnetic element of claim 1 wherein the plurality of thin film layers form a spin valve structure or a Magnetic Tunnel Junction (MTJ) structure.

3. The magnetic element of claim 2 wherein the plurality of thin film layers form a SAF structure having a fixed ferromagnetic layer (28) and a pinned ferromagnetic layer (24), the fixed ferromagnetic layer having a thickness greater than the pinned ferromagnetic layer to eliminate positive coupling between the fixed ferromagnetic layer and the free ferromagnetic layer.

4. The magnetic element of claim 2 wherein the plurality of thin film layers form a structure comprising a plurality of ferromagnetic layers having different switching fields, wherein the offset between the ferromagnetic layers provides a reduction in a demagnetization field between the ferromagnetic layers, thereby eliminating positive coupling between the ferromagnetic layers.

5. The magnetic element of claim 4 wherein the plurality of ferromagnetic layers includes a pinned ferromagnetic layer (24) and a free ferromagnetic layer (30), and the offset provides a reduction in a demagnetization field from the pinned ferromagnetic layer to the free ferromagnetic layer, thereby eliminating positive coupling between the pinned ferromagnetic layer and the free ferromagnetic layer.

6. The magnetic element of claim 2 wherein the plurality of thin film layers form a structure comprising a free ferromagnetic layer (30), a plurality of spacer layers (16), and a plurality of ferromagnetic layers having an anti-parallel alignment due to end-to-magnetostatic coupling, wherein a thickness of at least one of the plurality of ferromagnetic layers is adjusted to provide cancellation of a positive coupling between the free ferromagnetic layer and the at least one of the plurality of ferromagnetic layers.

7. A magnetic element, characterized by:

the first electrode (14) is characterized by a fixed ferromagnetic layer (28) having a thickness such that its magnetization is pinned in a preferred direction in the presence of an applied magnetic field of a specified strength₁(t₁) The pinned ferromagnetic layer (24) having a thickness₂(t₂) And a coupling interlayer (26) between the fixed ferromagnetic layer and the pinned ferromagnetic layer;

the second electrode (18) is characterized by a free ferromagnetic layer (30) having a surface whose magnetization is free to switch in the presence of a sufficient applied magnetic field;

a spacer layer (16) located between the fixed ferromagnetic layer of the first electrode and the free ferromagnetic layer of the second electrode;

in which the thickness t of the ferromagnetic layer is fixed₁Greater than the thickness t of the pinned ferromagnetic layer₂Thereby eliminating positive coupling between the fixed ferromagnetic layer and the free ferromagnetic layer; and

a substrate (12), first and second electrodes and a pad layer are formed on the substrate.