JP2008166507A - Magnetoresistance effect element and manufacturing method therefor, magnetic memory, magnetic head, and magnetic recording equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetoresistance effect element having a point contact, through which a high magnetoresistance effect can be obtained and its manufacturing method, and to provide a magnetic memory, a magnetic head, and magnetic recording equipment. <P>SOLUTION: The magnetoresistance effect element comprises an insulating base material, a first ferromagnetic layer formed on the principal plane of the base material, a second ferromagnetic layer formed being spaced apart from the first ferromagnetic layer on the principal plane of the base material, and a connecting portion, formed in between and in contact with the first ferromagnetic layer and the second ferromagnetic layer on the principal plane of the base material. The connecting portion contains first ferromagnetic crystal grains and second ferromagnetic crystal grains, with the crystal grain boundary between the first crystal grains and second crystal grains that is the narrowest part of a current passage between the first ferromagnetic layer and second ferromagnetic layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

 The present invention relates to a magnetoresistive effect element, a manufacturing method thereof, a magnetic memory, a magnetic head, and a magnetic recording apparatus, and particularly relates to a magnetoresistive effect element, a magnetic memory display input device, a manufacturing method thereof, and a magnetic head. The present invention also relates to a magnetic recording apparatus provided with this magnetic head.

  In recent years, the magnetic recording density in a hard disk drive has increased rapidly, and accordingly, the reproduction sensitivity and reproduction resolution required for the reproduction head have been increasing year by year. The emergence of GMR (Giant MagnetoResistance effect) heads using spin-dependent scattering as the operating principle has dramatically increased the output and corresponded to higher recording densities. In addition, a reproducing element structure for coping with further higher recording density has been proposed.

  Recently, non-volatile solid-state memory devices that handle magnetic domain walls in metal magnetic materials as information have been reported. The magnetic moment is determined based on the electron spin information, and the domain wall is formed at the boundary of the spin information. Therefore, the domain wall is not driven by a conventional magnetic field, but is driven by an electron current that can cope with further miniaturization. Research is underway.

A magnetoresistive element is disclosed in which a magnetic body having a constricted structure is provided between two magnetic bodies (Patent Document 1).
On the other hand, a domain wall is confined in a wire having a “neck” of two large and small magnetic bodies, and a low resistance (information “0”) for a large constriction, a high resistance (information “1”) for a small constriction, and “0” and “ The rewriting of “1” includes an element that moves the domain wall between the constrictions by current drive. The present inventor has confirmed that a magnetoresistive effect (MR) of about 10 to 20% is generated in a point contact in which a sputtered NiFe (permalloy) film is narrowed in two dimensions and three dimensions by ion milling. (Non-Patent Documents 1 and 2).

In these known techniques, a point contact is formed by patterning a magnetic material. However, even with the latest lithography technology, it is not easy to form an ideal point contact with good reproducibility, and further improvement of the magnetoresistive effect has not been realized.
JP 2002-270922 A Y. Ohsawa, “Current-driven resistance change and magnetoresistance measurements in NiFe films with a nanoconstriction,” IEEE Trans. Magn., Vol. 42, No. 10, p2615 (2006) Y. Ohsawa, “In-situ magnetoresistance measurements of a nanoconstricted NiFe film with in-plane configuration,“ IEEE Trans. Magn., Vol. 41, No. 10, p2577 (2005)

  The present invention provides a magnetoresistive effect element having a point contact capable of obtaining a high magnetoresistive effect, a manufacturing method thereof, a magnetic memory, a magnetic head, and a magnetic recording apparatus.

  According to an aspect of the present invention, an insulating base, a first ferromagnetic layer provided on a main surface of the base, and the first ferromagnetic layer on the main surface of the base A second ferromagnetic layer provided apart from the first ferromagnetic layer, and in contact with and in contact with the first ferromagnetic layer and the second ferromagnetic layer on the main surface of the base A first crystal grain made of a ferromagnetic material and a second crystal grain made of a ferromagnetic material, and the first ferromagnetic material layer and the second ferromagnetic material. The narrowest part of the path of the current flowing between the layers includes a connection portion that is a crystal grain boundary between the first crystal grains and the second crystal grains. A resistive effect element is provided.

  According to another aspect of the present invention, an insulating base, a first ferromagnetic layer provided on a main surface of the base, and the first ferromagnetic layer on the main surface of the base A second ferromagnetic layer provided apart from the ferromagnetic layer, and in contact with the first ferromagnetic layer and the second ferromagnetic layer on the main surface of the base. A path of a current flowing between the first ferromagnetic layer and the second ferromagnetic layer having a plurality of crystal grains made of a ferromagnetic material. There is provided a magnetoresistive effect element characterized in that the narrowest portion is a connection part which is a crystal grain boundary.

  According to another aspect of the present invention, an insulating base, a first ferromagnetic layer provided on a main surface of the base, and the first ferromagnetic layer on the main surface of the base A second ferromagnetic layer provided apart from the ferromagnetic layer, and in contact with the first ferromagnetic layer and the second ferromagnetic layer on the main surface of the base. A first crystal grain made of a ferromagnetic material and a second crystal grain made of a ferromagnetic material, the direction of magnetization of the first ferromagnetic material layer And a connection part in which a domain wall is formed at a crystal grain boundary between the first crystal grain and the second crystal grain when the magnetization direction of the second ferromagnetic layer is different from that of the second ferromagnetic layer. A magnetoresistive effect element is provided.

  According to another aspect of the present invention, an insulating base, a first ferromagnetic layer provided on a main surface of the base, and the first ferromagnetic layer on the main surface of the base A second ferromagnetic layer provided apart from the ferromagnetic layer, and in contact with the first ferromagnetic layer and the second ferromagnetic layer on the main surface of the base. Formed by depositing a ferromagnetic material on the main surface of the base between the first ferromagnetic layer and the second ferromagnetic layer. A narrowest part of a current path flowing between the first ferromagnetic layer and the second ferromagnetic layer is a grain boundary. And a magnetoresistive effect element characterized by comprising:

  According to another aspect of the present invention, a first ferromagnetic layer and a second ferromagnetic layer are formed on a main surface of an insulating base, and the first ferromagnetic body is formed. A ferromagnetic material is deposited on the main surface of the base between the layer and the second ferromagnetic material layer to electrically connect the first ferromagnetic material layer and the second ferromagnetic material layer. A method of manufacturing a magnetoresistive effect element is provided, characterized in that a connection part connected to the magnetoresistive element is formed.

  According to another aspect of the present invention, a first layer made of a ferromagnetic material is formed on a main surface of an insulating base, and the first layer and at least the base under the first layer are formed. Are selectively removed, and the first layer is further selectively removed, whereby the first ferromagnetic layer and the second ferromagnetic layer are separated, and the first strong layer is separated. A ferromagnetic material is deposited on the main surface between the magnetic material layer and the second ferromagnetic material layer to electrically connect the first ferromagnetic material layer and the second ferromagnetic material layer. A method of manufacturing a magnetoresistive effect element is provided, wherein a connection portion to be connected is formed.

  According to another aspect of the present invention, any one of the magnetoresistive elements described above is provided, and a current is passed between the first ferromagnetic layer and the second ferromagnetic layer. Provides a magnetic memory characterized by performing at least one of writing and reading.

  According to another aspect of the present invention, there is provided a magnetic head comprising any one of the above magnetoresistive elements and capable of reading information magnetically recorded on a magnetic recording medium. Provided.

  According to another aspect of the present invention, there is provided a magnetic recording apparatus including the above magnetic head.

  According to the present invention, there are provided a magnetoresistive effect element having a point contact capable of obtaining a high magnetoresistive effect, a manufacturing method thereof, a magnetic memory, a magnetic head, and a magnetic recording apparatus.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a conceptual diagram showing a planar structure of a magnetoresistive element according to an embodiment of the present invention. The magnetoresistive effect element 10 according to the present embodiment includes an insulating base 20, a first ferromagnetic layer 30 provided on the main surface, a second ferromagnetic layer 40, the first and second layers And a connecting portion 50 provided between and in contact with the second ferromagnetic layers 30 and 40.

The first and second ferromagnetic layers 30 and 40 and the connection portion 50 are both made of a ferromagnetic material and arranged along the first direction X. The distance between the first ferromagnetic layer 30 and the second ferromagnetic layer 40 can be, for example, about 10 to several tens of nm. The connection part 50 has the narrowest part 50P with the narrowest width along the second direction Y perpendicular to the first direction X. The narrowest portion 50P is a crystal grain boundary where the first crystal grain 50A and the second crystal grain 50B are in contact with each other. This narrowest part 50P acts as a point contact. Although only two crystal grains 50A and 50B are shown in FIG. 1, the connecting portion 50 may include three or more crystal grains.
The magnetic body in the vicinity of the narrowest portion 50P has a structure in which crystal grains 50A and 50B oriented in different directions on the main surface of the base 20 are connected. The crystal grain boundaries of the crystal grains 50A and 50B are point contacts that confine the domain wall. The size of the crystal grains 50A and 50B is 10 to 20 nm according to normal formation conditions, and is about 3 to 5 nm even in the initial stage of growth. Accordingly, the width of the grain boundary of the narrowest portion 50P to which the two crystal grains 50A and 50B are connected is sufficiently small, and a narrow point contact is formed. As a result, a high magnetoresistance effect is obtained.

  Moreover, by connecting crystal grains, atomic dislocations / defects in the order of atomic distance are introduced into the grain boundaries. Thereby, for example, a region having a length of 1 nm or less and a reduced exchange stiffness is introduced, and the domain wall is confined in that portion.

  Further, by connecting units of crystal grains whose physical size is determined to some extent, the cross-sectional area of the magnetic material in the vicinity of the narrowest portion (point contact) 50P can be changed steeply and discontinuously. By doing so, the domain wall energy proportional to the domain wall area rapidly increases when it is away from the narrowest portion (point contact) 50P, and the localization to the narrowest portion 50P is increased, thereby making it easier to form a narrower domain wall. . In addition, the domain wall that has moved to the narrowest portion 50P is easily confined in the narrowest portion 50P, so that it is easy to obtain a stable resistance value.

  In addition, impurities that are not contained in the crystal grains often segregate at the crystal grain boundaries. In other words, the composition of the narrowest portion 50P is different from that of the crystal grains 50A and 50B, whereby the exchange stiffness can be further reduced. For example, oxygen (O) is localized in the narrowest portion 50P. Then, the electron polarization due to the electrons in the 2p orbit is improved, leading to an improvement in the magnetoresistance effect.

  As a method of forming the magnetoresistive effect element of the present embodiment, as will be described in detail later, a gap having a regulated length and width is formed between the first and second ferromagnetic layers 30 and 40. A method of forming the connection portion 50 by depositing a ferromagnetic material on the main surface of the base 20 exposed in this gap can be mentioned. In this case, island-like to network-like structures are formed in the initial growth process in which the connection portions 50 are deposited. That is, the crystal nuclei formed in an island shape grow as crystal grains, and the portion where adjacent crystal grains are in contact with each other can be the narrowest portion 50P.

  When using the conventional top-down formation method, it is extremely difficult to form a discontinuous shape without breaking the connection between the grains, and the narrowest part matches the grain boundary. You can only rely on it by chance. On the other hand, according to this embodiment, it becomes easy to make the connection part, ie, a crystal grain boundary, between crystal grains the narrowest part 50P. The bonding of the crystal grain boundary of the narrowest portion 50P by a polycrystal is ideal for obtaining a sharp narrowing and a domain wall. For example, Patent Document 1 discloses the bonding of such a crystal grain boundary. It has not been.

Here, as the material of the base 20, various insulating materials such as alumina and MgO can be used, for example.
The first and second ferromagnetic layers 30 and 40 and the connection portion 50 may be made of, for example, iron (Fe), cobalt (Co), nickel (Ni), iron (Fe), cobalt ( Co), nickel (Ni), manganese (Mn), and an alloy containing at least one element selected from the group consisting of chromium (Cr), oxide, nitride or Heusler alloy, iron (Fe), cobalt ( A compound semiconductor or an oxide semiconductor containing at least one element of Co), nickel (Ni), manganese (Mn), and chromium (Cr), and having ferromagnetism can be given.
For the ferromagnetic layer 40 to be sensitive to an external magnetic field, a material having a relatively low coercive force such as NiFe (permalloy) is used, and a Fe-based material having a high electronic polarizability is used as a material for the connection part 50 that causes electron scattering. By using a base material such as Fe, FeCo, or FeCoNi Heusler alloy, high magnetic field sensitivity and high resistance change can be obtained.
Moreover, as a material of the antiferromagnetic material layer 60, for example, various antiferromagnetic materials such as PtMn and IrMn can be used. Instead of the antiferromagnetic material layer 60, a hard magnetic material layer made of a hard magnetic material having a high coercive force of 500 Oe (Oersted) or more such as CoPt or CoPtCr is provided, and the ferromagnetic material layer 30 (or 40) is provided. Magnetization may be fixed.

Hereinafter, the magnetoresistive effect element of the present embodiment will be described in more detail with reference to examples.
(First embodiment)
2A and 2B are schematic views showing the magnetoresistive effect element according to the first embodiment of the present invention. FIG. 2A is a perspective view thereof, and FIG. 2B is a plan view of the main part thereof. 2 and the subsequent drawings, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.
The magnetoresistive effect element 10 of the present embodiment includes a first ferromagnetic layer 30 and a second ferromagnetic layer 40 provided on the main surface of the base 20 made of an insulating material, and a gap between them. And a connecting portion 50 provided. The base 20 is provided with grooves G from both sides thereof, and a connecting portion 50 is formed on the base having a narrow width sandwiched between the pair of grooves G. The groove G does not need to penetrate the base 20 in the thickness direction, and may be a recess recessed downward from the main surface on which the first ferromagnetic layer 30 and the like are provided. The connection part 50 has a polycrystalline structure in which a plurality of crystal grains are connected to each other, and among these, the crystal grain boundary where the first crystal grain 50A and the second crystal grain 50B are in contact is the narrowest part. 50P is configured.
Further, an antiferromagnetic layer 60 is laminated on the first ferromagnetic layer 30, and the magnetization direction of the first ferromagnetic layer 30 is fixed in a predetermined direction. On the other hand, the magnetization of the second ferromagnetic layer 40 is not fixed, and its direction is variable by a magnetic field applied from the outside. In addition, electrodes 70 are connected to the first ferromagnetic layer 30 and the second ferromagnetic layer 40, respectively.

  This magnetoresistive effect element 10 produces a high magnetoresistance effect by using the first ferromagnetic layer 30 as a magnetization fixed layer (pinned layer) and the second ferromagnetic layer 40 as a magnetization free layer (free layer).

FIG. 3 is a schematic diagram of a main part for explaining the magnetoresistive effect in the magnetoresistive effect element 10 of the present embodiment.
The magnetization M of the first ferromagnetic layer 30 as the pinned layer is fixed in the direction shown in FIG. On the other hand, the magnetization M of the second ferromagnetic layer 40 as a free layer can be rotated by an external magnetic field. FIG. 3A shows a state in which the external magnetic field (Hsig) is zero.

  The grain size (GL) along the first direction X of the crystal grains 50A and 50B on both sides of the narrowest part 50P formed in the connection part 50 can be set to, for example, about several nm to 10 nm. In this way, the sum (2GL) of the grain sizes (GL) of the crystal grains 50A and the crystal grains 50B is larger than the mean free path MFP of electrons (2GL> MFP). The crystal grains 50C are interposed between the crystal grains 50A and the first ferromagnetic layer 30 and between the crystal grains 50 and the second ferromagnetic layer 40. These crystal grains 50C transmit the direction of the magnetization M of the ferromagnetic layers 30 and 40 and the sense current. That is, among the crystal grains 50C, those between the first ferromagnetic layer 30 and the narrowest portion 50P have the direction of magnetization M of the first ferromagnetic layer 30 in the narrowest portion (point contact). ) Transmit to 50P. On the other hand, the crystal grains 50C provided between the second ferromagnetic layer 30 and the narrowest portion 50P change the direction of the magnetization M of the second ferromagnetic layer 40 to the narrowest portion (point contact) 50P. introduce.

  In the state shown in FIG. 3A, the magnetization M of the second ferromagnetic layer 40 as the free layer is substantially perpendicular to the magnetization M of the first ferromagnetic layer 30 as the pinned layer. is there. Then, the magnetization M of the first and second ferromagnetic layers 30 and 40 is transmitted to the crystal grains of the adjacent connection part 50 as indicated by the arrow 50M, and the domain wall formed in the narrowest part 50P. Are adjacent. That is, in the state shown in FIG. 3A, the domain wall of the narrowest portion 50P is 90 degrees.

FIG. 3B shows a state in which an external magnetic field (Hsig) in the opposite direction to the magnetization M of the first ferromagnetic layer 30 is applied.
When an external magnetic field (Hsig) in the opposite direction to the magnetization M of the first ferromagnetic layer 30 is applied, the magnetization M of the second ferromagnetic layer 40 rotates in the inflow direction. Then, this magnetization is transmitted to the crystal grains 50C of the connection portion 50 adjacent to the second ferromagnetic layer 40, as indicated by the arrow 50M, and the narrowest portion (point contact) 50P has a corresponding response. A steep domain wall is formed. That is, since the magnetization close to the opposite direction to the magnetization M of the first ferromagnetic layer 30 is transmitted from the second ferromagnetic layer 40 side to the narrowest portion 50P, the narrowest portion 50P has about A 180 degree domain wall is formed.

  That is, as shown in FIG. 3A, when the external magnetic field (Hsig) is zero, a domain wall (spin rotation) of about 90 degrees is formed in the narrowest portion 50P, whereas the external magnetic field is Is applied, a domain wall of about 180 degrees enters, and the amount of spin rotation within the narrowest portion 50P increases. As a result, electron scattering at the narrowest portion 50P increases, and the resistance value increases.

  In this case, it is desirable that the mean free path (MFP) of electrons in the magnetic material is smaller than the sum of the grain sizes of the crystal grains 50A and the crystal grains 50B (2GL). Scattering of electrons flowing from one of the crystal grains 50A and the crystal grains 50B into the narrowest portion 50P depends on the state of the domain wall formed in the narrowest portion 50P. That is, when the spin rotation angle at the narrowest part 50P is 0 degree (no domain wall), scattering does not occur, while the spin rotation angle at the narrowest part 50P is 180 degrees (corresponding to a 180 degree domain wall). Sometimes electron scattering is maximal.

Here, the magnetoresistance effect is given as a resistance change rate (MR ratio) according to the following equation.

MR ratio = 100 × (Rhigh−Rlow) / Rlow (1)

As can be seen from the equation (1), in order to increase the rate of resistance change, it is effective to reduce Rlow, which is an additional resistance generated without a domain wall, as much as possible. It is before and after the narrowest portion 50P that is most narrowed down in shape that greatly affects the resistance of Rlow. Before and after the narrowest part 50P, if the scattering by the crystal grain boundary or the like is suppressed as much as possible while electrons move through the mean free path (MFP) distance, a low resistance value is obtained which is close to that of an element formed of a single crystal. By increasing the sum (2GL) of the grain sizes of the crystal grains 50A and 50B (2GL> MFP) rather than the mean free path (MFP) of electrons, the crystal grains while the electrons travel the mean free path distance. It is possible to suppress scattering by the field. That is, when electrons pass through the crystal grains 50A and 50B, respectively, scattering by the crystal grain boundary during the movement of the mean free path is suppressed, and Rlow can be lowered. Since the mean free path of electrons in the ferromagnetic material is about several nanometers, the above-mentioned conditions can be easily satisfied. This is a unique effect due to the fact that the mean free path of a general metal magnetic material is shorter than that of a non-magnetic good conductor such as copper (Cu) and the mean free path.

  Note that the resistance from the first ferromagnetic layer 30 to the narrowest portion 50P and the resistance from the second ferromagnetic layer 40 to the narrowest portion 50P are reduced by reducing the number of crystal grains 50C constituting the connection portion 50. Rlow can be further lowered by lowering each of the values.

Next, a method for manufacturing the magnetoresistive effect element of this example will be described.
4 to 6 are process perspective views showing the method of manufacturing the magnetoresistive effect element according to this embodiment.
First, as shown in FIG. 4A, a ferromagnetic layer 100 made of permalloy (NiFe alloy) or the like is formed on an underlayer 20 made of alumina to a thickness of about 10 nm. Then, as shown in FIG. 4B, an antiferromagnetic layer 60 made of PtMn is formed to a thickness of about 20 nm at a predetermined position to be the first ferromagnetic layer 30. Thereafter, in order to protect the surfaces of the NiFe layer 100 and the PtMn antiferromagnetic layer 60 from the etching process, a mask 200 is formed as shown in FIG. As the mask 200, for example, a SiO ₂ film having a thickness of about 0.1 μm can be formed.
Next, as shown in FIG. 4D, gold (Au) having a thickness of about 0.2 μm is formed as the electrode 70 for supplying the sense current. The electrode 70 is not shown in the subsequent steps for convenience of explanation.

  Next, as shown in FIG. 5A, etching is performed from the mask 200 to the base 20 along the edge of the antiferromagnetic material layer 60 (which appears as a step on the mask 200). A groove of about 10 nm is formed. For this etching, for example, a focused ion beam (FIB) 300 can be used. FIG. 5B is a conceptual diagram showing the surface of the base 20 after etching separated. Grooves G are formed with focused ion beams 300 from both the left and right ends, and only the portion where the connection portion 50 is formed later is left as the bridge 20B.

  Next, as shown in FIG. 5C, the magnetic layer 100 remaining on the bridge 20B is removed by ion milling to expose the base of the bridge 20B. At this time, the other ferromagnetic layer 100 is protected by the mask 200. Accordingly, the first ferromagnetic layer 30 and the second ferromagnetic layer 40 are separated on the left and right of the groove G. Note that the step of removing the magnetic layer 100 remaining on the bridge 20B may be performed by, for example, sputter etching or the like before the formation of the connection portion 50 described later with reference to FIG.

  Next, a ferromagnetic material such as NiFe is deposited, and the connection portion 50 is formed on the bridge 20 </ b> B of the base 20. As a deposition method, for example, as shown in FIG. 6A, a method of irradiating the target 600 such as NiFe with the ion beam 500 and performing sputtering can be used. Further, the amount to be deposited can be about 3 nm in average film thickness, for example.

  However, this invention is not limited to this method, For example, a vacuum evaporation method etc. may be sufficient. When a ferromagnetic material is deposited by sputtering or vacuum evaporation, first, crystal grain nuclei are formed and grow as crystal grains, and adjacent crystal grains eventually come into contact with each other. It is also conceivable that crystal nuclei of the deposited material are formed on the end faces of the first ferromagnetic layer 30 and the second ferromagnetic layer 40, and crystal grains grow preferentially. Therefore, the crystal grains 50A and 50B can be grown between the ferromagnetic layers 30 and 40, and these can be brought into contact with each other to form the narrowest portion 50P.

  Further, the deposition step shown in FIG. 6A is preferably performed while a sense current is supplied to the electrode 70 (see FIG. 4D) and the resistance value of the element is measured. That is, while the first ferromagnetic layer 30 and the second ferromagnetic layer 40 are separated, the resistance between the electrodes 70 is close to infinity. Then, when a ferromagnetic material such as NiFe is deposited on the bridge 20 </ b> B and the connection portion 50 is formed and the first ferromagnetic layer 30 and the second ferromagnetic layer 40 are connected, the electrode 70. , 70 resistance rapidly decreases. When the deposition of the ferromagnetic material is stopped at the timing when the resistance between the electrodes 70 and 70 suddenly decreases, the crystal grains 50A and 50B grow and come into contact with each other as shown in FIG. It is possible to stop the deposition at the formation timing.

Finally, as a protective film (not shown), for example, SiO ₂ is deposited to a thickness of about 0.1 μm to protect the entire device, thereby preventing oxidation and physical alteration of the connection portion 50. Thus, as shown in FIG. 6B, the magnetoresistive element of this example is completed.

Also, in this case, if too much ferromagnetic material is deposited, the process returns to the etching process shown in FIG. 5C again, and the connecting portion formed on the bridge 20B is removed. Then, the deposition process shown in FIG. At this time, if the etching process shown in FIG. 5C and the deposition process shown in FIG. 6A are performed in the same vacuum chamber, a clean surface can be maintained without exposure to the atmosphere. .
FIG. 7 is a graph showing the characteristics obtained in the magnetoresistive effect element prototyped by the present inventor by the method described above.
In FIG. 7, the MR ratio against the bias voltage applied between the electrodes 70 is plotted. In addition, the device resistance of the magnetoresistive effect element made as a trial was about 15 kΩ. When the bias voltage is about +/− 150 mV, the MR ratio is 1% or less, but when the bias voltage is increased to about +/− 600 mV, a large MR ratio of 100% or more is obtained.

  In the prior example of Non-Patent Document 1 in which the inventor formed a point contact using the same NiFe as the MR film by using a top-down technique, the resistance of the element is about 18 kΩ, and the MR ratio is 10 to 20 %Met.

  On the other hand, in this example, although the resistance value of the element was a little as low as about 15 kΩ, the obtained MR ratio was remarkably large at 140%. As described above with reference to FIGS. 1 and 3, this is considered to be because the magnetoresistive effect element in which the point contact is formed by the bottom-up method and the crystal grain boundary is the narrowest portion 50P can be realized.

  In the case of a tunneling MR element (TMR) in which the electrical conduction path is electrically interrupted between the electrodes, the MR ratio tends to decrease as the bias voltage is increased. On the other hand, in the case of the magnetoresistive effect element of this example, the MR ratio increases as the bias voltage increases. That is, it was confirmed that the magnetoresistive effect element of this example was based on a physical phenomenon that is essentially different from TMR. Further, the magnetoresistive effect element of this embodiment is very advantageous for high output because the MR ratio increases when the bias voltage is increased (the sense current is increased). That is, when the sense current is increased to obtain a high output, the MR ratio increases and a higher output can be obtained.

In the step of forming the connection portion 50 described above with reference to FIG. 6A, not only the ferromagnetic material but also a nonmagnetic element may be added as an impurity. For example, when the end portion of the mask 200 made of SiO ₂ is sputtered by sputtered particles of ferromagnetic material, an ion beam or the like, oxygen (O) which is a constituent component thereof is added to the connection portion 50. Alternatively, oxygen is added to the connection part 50 when oxygen gas is added or oxygen plasma is irradiated when the connection part 50 is formed. Since the element added in this way has a large tendency to segregate at the grain boundary, it can be localized at the narrowest portion 50P, that is, the point contact. When an impurity element such as oxygen is localized at the point contact, the electronic polarizability can be improved. This is preferable from the viewpoint of obtaining a large resistance change rate.

  Note that impurities to be added include not only oxygen but also other non-magnetic elements (for example, platinum (Pt) contained in the antiferromagnetic layer 60, silicon (Si) contained in the mask 200, electrodes, (Au) contained in 70. These impurities contribute to high MR by reducing the exchange stiffness in the point contact and forming a narrow domain wall. For example, in the case of gold (Au), if it is several at (atomic)% or less, the effect of lowering the exchange stiffness works more than the reduction of its electronic polarizability, and as a result, higher MR can be obtained. Is possible.

On the other hand, in the present embodiment, it is also possible to use the migration effect of the connection unit 50.
FIG. 8 is a schematic diagram for explaining the migration effect.
Since the narrowest part 50P of the magnetoresistive effect element of this embodiment is extremely narrow, it is considered that the atoms constituting the connection part 50 migrate reversibly by applying a high bias voltage. By operating the magnetoresistive element at a bias point that causes reversible migration, the narrowest portion 50P, that is, the point contact can be further narrowed down. By narrowing down the narrowest portion 50 and reducing its cross-sectional area, it is possible to narrow the domain wall width and obtain a larger resistance change. FIG. 8A shows a state before migration occurs, and FIG. 8B shows a state after migration. FIG. 8B shows a state before migration (broken line) and a state where migration is performed by applying an appropriate high bias voltage (solid line). The atoms near the narrowest portion 50 of the connection portion 50 are attracted to both sides by the bias, and the contact area of the narrowest portion 50 is reduced. As a result, a narrower domain wall can be formed than when no bias is applied (before migration), and a large MR ratio can be expected. This is an effect peculiar to a magnetic device that uses a domain wall as a scatterer, and does not increase or decrease the contact area unlike a physical switch made of a non-magnetic metal, so that high reliability can be obtained.
When the formation process of the connection portion 50 described above with reference to FIG. 6A is performed by electron beam evaporation in a high vacuum, the grown particles become larger than those formed by ion beam sputtering, so that bias is applied. The migration effect is expected to increase.

  FIG. 9 is a schematic diagram showing a modification of the magnetoresistive effect element according to the present embodiment. FIG. 9A is a cross-sectional view corresponding to FIG. 1B, and FIG. FIG.

  In this modification, the main surface of the base 20 between the first ferromagnetic layer 30 and the second ferromagnetic layer 40 is recessed in a concave shape. That is, the portion corresponding to the bridge 20B is retracted downward. Such a shape can be formed, for example, by etching the main surface of the underlayer 20 after etching the magnetic layer 100 in the etching step described above with reference to FIG. Alternatively, it can be formed by etching the surface of the bridge 20B prior to the formation of the connecting portion 50 described above with reference to FIG.

  A connecting portion 50 is formed on the recessed base 20 and a crystal grain boundary is provided in the narrowest portion 50P to trap the domain wall. Thus, when the connection part 50 is formed on the concave base 20, it becomes easy to form the cross-sectional area of the narrowest part 50P narrowly. As a result, higher MR is easily obtained.

  A positive charge is generated in the connection portion 50 formed on the base 20 recessed in a concave shape, and a domain wall is easily formed.

  That is, in general, magnetization is generated at a position bent along the direction of magnetization or a cross-sectional area is narrowed, and a demagnetizing field is generated when the magnetization is generated, so that a domain wall is formed. Therefore, the connection portion 50 formed on the concave main surface as in this modified example is more easily magnetized than the connection portion 50 formed on the flat main surface, and the narrowest narrowest portion among them. The domain wall is most likely to occur in the portion 50P. That is, the domain wall is likely to be generated in the narrowest portion 50P where the resistance value is highest.

  In the present embodiment, since the connection portion 50 is a polycrystal, the cross-sectional area of the current path changes discontinuously when passing through the crystal grain boundary. Therefore, in addition to the narrowest part 50P, magnetization is generated for the above reason, and the localization of the domain wall is increased. As a result, the movement of the domain wall due to thermal disturbance is prevented, and the reliability of the magnetoresistive element or the magnetic memory is increased.

  In the initial stage of thin film growth, the density of the thin film is lower than that of the bulk and tends to be tensile stress. The narrowest portion 50P, which is the narrowest joint portion, is susceptible to deterioration (change in width size and the like) due to stress migration. The main surface of the base 20 under the connecting portion 50 is recessed to disperse the stress, the local stress on the narrowest portion 50P is relieved, and the deterioration of the magnetoresistive effect element due to stress migration is suppressed. Can do.

  In this modification, the amount of concave depression on the main surface can be controlled by controlling the etching amount of the base 20 before the connection portion 50 is formed, which leads to the control of the stress of the connection portion 50. That is, by controlling the interatomic distance as viewed in the direction of electron conduction, it is possible to locally generate an electronic state such as the degree of spin polarization that is difficult to obtain in the bulk. As a result, the magnetic field sensing can obtain a large resistance change by changing the local electronic state in the connection part 50 related to electron-dependent scattering while maintaining the bulk characteristics of the ferromagnetic layer 40 with low coercive force. In general, it is possible to obtain both high magnetic field sensitivity and high resistance change which are generally difficult. That is, it is possible to achieve both high magnetic field sensitivity and high resistance change by using the same material without using different materials for the ferromagnetic layer 40 and the connection portion 50, leading to cost reduction of the magnetoresistive element.

(Second embodiment)
FIG. 10 is a schematic view showing a magnetoresistive effect element according to a second embodiment of the present invention, FIG. 10 (a) is a perspective view thereof, and FIG. 10 (b) is a plan view of its main part.
In this embodiment, an antiferromagnetic layer 80 is also laminated on the second ferromagnetic layer 40, and its magnetization M is fixed in the direction opposite to the magnetization M of the first ferromagnetic layer 30. ing. The first and second ferromagnetic layers 30 and 40 can be formed of NiFe having a thickness of about 10 nm, for example. Further, when the antiferromagnetic material layer 60 and the antiferromagnetic material layer 80 are formed of antiferromagnetic materials having different Neel temperatures, it becomes easy to impart magnetizations in opposite directions by annealing in a magnetic field. Specifically, the antiferromagnetic material layer 60 can be formed of PtMn, and the antiferromagnetic material layer 80 can be formed of IrMn.
In FIG. 10B, the direction of the magnetization M is parallel and antiparallel to the first direction X, but may be parallel and antiparallel to the second direction Y. Furthermore, instead of either one or both of the antiferromagnetic layers 60 and 80, for example, a hard magnetic layer made of a hard magnetic material having a coercive force of 500 Oe or more may be provided.

If such a magnetoresistive effect element is used, a memory for storing information by moving the position of the domain wall by spin current becomes possible.
FIG. 11 is a schematic diagram for explaining the operation of the magnetoresistive element of this example.
Since the magnetizations of the first and second magnetic layers 30 and 40 are fixed in opposite directions, the magnetization of the connection portion 50 connected to these ferromagnetic layers is represented by an arrow 50M in FIG. As described above, the narrowest portion 50P tends to face the same direction as the magnetization M of the ferromagnetic layers 30 and 40, respectively. The narrowest part 50P has a domain wall of 180 degrees.

  When a current is passed through such a magnetoresistive effect element, the domain wall can be moved, and the resistance changes accordingly. For example, in FIG. 11B, the domain wall resistance is highest when the domain wall is present at the position I0 of the narrowest portion 50P having the narrowest width (for example, information “0”). When the domain wall moves between the crystal grains 50A and 50C, the junction width of the domain wall increases (position I1), and the resistance decreases. Such movement of the domain wall is performed by the current supplied to the electrode 70, and when the power source is connected in the direction of the symbol A, the maximum current density Jc or more is reached by the spin current supplied from the second magnetic layer 40. The domain wall in the narrow part 50P is pushed and moved. The domain wall remains at the junction (position I1) at the grain boundary (between the crystal grains 50A and 50C) where the cross-sectional area changes discontinuously. This is because the cross-sectional area spreads discontinuously and rapidly at the position I1, so that the current density is lowered and the pressure due to the spin current to the domain wall is lowered. As a result, since the junction area at the position I1 is large, the domain wall width is widened and low resistance is exhibited (for example, information “1”). Even if the current is further increased, the domain wall stops at the position I3 where the magnetization is fixed by the antiferromagnetic material layer 60, so that the low resistance state (for example, information “1”) at the position I3 is maintained. Is done.

  On the other hand, by reversing the polarity of the connection of the power supply as shown by reference sign B and increasing the current density to be higher than Jc, the domain wall at position I1 returns to position I0 (high resistance, for example, information “0”), If it adds, it will move to the position I2 (low resistance, for example, information "1") between the crystal grains 50B and 50C. Even if the current is further increased, the domain wall stops at the position I4 where the magnetization is fixed by the antiferromagnetic material layer 80, so that the low resistance state (for example, information “1”) at the position I4 is maintained. Is done.

  The discontinuous change in the junction area does not need to change perpendicular to the macro current path (the straight line L between the first ferromagnetic layer 30 and the second ferromagnetic layer 40). It may be diagonal as exemplified in the position I1. For example, there is no problem even if the positions I0, I2 and the like enter obliquely as in the position I1 and are stable in terms of magnetostatic energy, which is desirable in terms of information stability.

  In the present embodiment, recording can be performed by moving the domain wall position by changing the polarity of the current in this way. By passing a sense current having a critical current density Jc or less, the resistance value can be read and acquired as information “1” or “0”. In this embodiment, the connection part 50 has a structure in which a plurality of crystal grains are connected, and the connection area inevitably changes discontinuously at the grain boundaries of these crystal grains. When formed using a top-down method such as lithography, the shape of the processing edge becomes gentle, and it is quite accidental to match the crystal grain boundary with the domain wall position. Since the domain wall energy is minimized at the portion where the cross-sectional area is minimized (the constricted portion of the crystal grain connection portion), the domain wall tends to be trapped in this portion. For this reason, the magnetoresistive effect element according to the present embodiment utilizes the constriction of the connection portion between crystal grains by a bottom-up structure called magnetic particles, so that information can be moved on a particle size scale and recorded (information Rewriting) can be done quickly.

  By making the mean free path (MFP) of electrons smaller than the sum of the grain sizes of the crystal grains 50A and 50B (2GL) (2GL> MFP), an unnecessary increase in the low resistance state as a base is achieved. Therefore, an element having a large resistance change can be provided.

(Third embodiment)
Next, a memory array will be described as a third embodiment of the present invention.
FIG. 12 is a schematic diagram showing a memory in which magnetoresistive elements are arranged in an array.
A combination of a pair of ferromagnetic layers 30 and 40 in which the directions of the magnetization M are opposite to each other are arranged in an array. A connection portion 50 is provided between the ferromagnetic layers 30 and 40. When a large number of magnetoresistive elements are formed like a memory, it is inefficient to form point contacts one by one by a method such as electron beam drawing, but according to this embodiment, a pair of ferromagnetic elements A connection having the narrowest portion 50P in a bottom-up manner by forming a combination of body layers 30 and 40 in an array and then depositing a ferromagnetic material in the manner described above with reference to FIG. The part 50 can be formed simultaneously for all the magnetoresistive elements. That is, it is extremely advantageous in terms of time and cost required for manufacturing.

  13 and 14 are process diagrams showing a method for manufacturing the memory array of this embodiment. Here, FIGS. 13 (a) and (c) and FIGS. 14 (a) and (c) are plan views, and FIGS. 13 (b) and (d), FIGS. 14 (b) and (d) are diagrams, respectively. It is sectional drawing corresponding to the AA line cross section of 13 (a).

First, as shown in FIGS. 13A and 13B, a ferromagnetic layer 100 made of permalloy (NiFe alloy) or the like is formed on the main surface of the base 20 such as alumina to a thickness of about 10 nm. Then, an antiferromagnetic layer 60 such as PtMn having a thickness of about 20 nm is formed at a predetermined position to be the first ferromagnetic layer 30.
Next, as shown in FIGS. 13C and 13D, an antiferromagnetic layer 80 such as IrMn having a thickness of about 20 nm is formed at a position to become the second ferromagnetic layer 40. Thus, when antiferromagnetic materials having different Neel temperatures are used for the antiferromagnetic material layers 60 and 80, it becomes easy to fix the magnetization in antiparallel. That is, at the time of annealing in the magnetic field, the temperature is lowered while performing the heat treatment in the magnetic field at 240 degrees Celsius, and the magnetization M of NiFe of the first ferromagnetic layer 30 (PtMn side) is fixed in one direction. The direction of the magnetic field applied at a temperature of about 120 degrees Celsius is reversed and the magnetization M of NiFe on the second ferromagnetic layer 40 side (IrMn side) is antiparallel to the first ferromagnetic layer 30 To. Here, the sizes of the first ferromagnetic layer 30 and the second ferromagnetic layer 40 are, for example, the width X = 100 nm, the length Y = 500 nm, and the interval between the adjacent first ferromagnetic layers 30. S = 500 nm, and the distance G between the first and second ferromagnetic layers 30 and 40 can be about 10 nm.

  Next, as shown in FIGS. 14A and 14B, the ferromagnetic layer 100 around the antiferromagnetic layers 60 and 80 is removed, and the base 20 is further etched to form a groove G. As a result, the bridge 20B is formed. The width of the bridge 20B can be about 30 nm, for example.

  Thereafter, as described above with reference to FIG. 6A, a ferromagnetic material is deposited to form the connection portion 50. For example, NiFe is deposited by electron beam evaporation in a high vacuum with an average film thickness of 3 nm. The substrate temperature at that time can be set to 350 degrees Celsius.

  As shown in FIGS. 6C and 6D, the ferromagnetic material grows at a portion other than the bridge 20B, but the interval between the adjacent first ferromagnetic material layers 30 is increased to, for example, 500 nm. Therefore, they are not connected by a ferromagnetic material.

  Further, in the process of forming the connection portion 50, if a portion other than the bridge 20B is hidden with a mask, a short circuit in a portion other than the bridge 20B can be suppressed. Therefore, it is possible to reduce the interval between the magnetoresistive effect elements and increase the density. Further, by repeating the processes of FIGS. 5C and 6A as necessary, unnecessary ferromagnetic deposits can be erased.

(Fourth embodiment)
FIG. 15 is a schematic diagram showing a magnetoresistive effect element according to a fourth embodiment of the present invention.
Also in this embodiment, the magnetization M of the first ferromagnetic layer 30 and the magnetization M of the second ferromagnetic layer 40 are fixed in opposite directions. The connection portion 50 formed between the ferromagnetic layers 30 and 40 has a portion in which the crystal grains 50B, the crystal grains 50A, and the crystal grains 50B are connected in this order. A narrowest portion 50P is formed between these crystal grains. That is, the magnetoresistive effect element of this embodiment has two narrowest portions 50P, that is, point contacts. The widths (cross-sectional areas) of these two narrowest portions 50P are substantially the same, but are not necessarily exactly the same. It is sufficient that the cross-sectional area of the narrowest part 50P is somewhat smaller than the cross-sectional area of the other part of the connection part 50.

  Note that a plurality of crystal grains may be provided between the two narrowest portions 50P instead of the single crystal grain 50A. In addition, since the cross-sectional area of the current path before and after each narrowest portion 50P is discontinuous, the localization of the domain wall at the discontinuous position is improved, and the domain wall is held at a position where the cross-sectional area is large. What has been done is to trap the domain wall against the long-term magnetization change due to thermal disturbance (the domain wall position moves to the narrowest position with the lowest domain wall energy in the long term) and suppress the change, heat resistance・ Reliability is improved.

Similarly to the second embodiment, when the polarity of the power source is represented by the symbol A, the positions I1 and I3 are the positions of the domain walls exhibiting low resistance. Further, when the polarity of the power source is represented by the symbol B, the positions I2 and I4 are domain wall positions indicating low resistance (for example, information “1”). In the present embodiment, since the narrowest portion 50P is provided at two locations, the state where the domain walls exist at these positions I01 and I02 corresponds to high resistance (for example, information “0”). The resistance when there is a domain wall at these positions I01 and I02 depends on the cross-sectional area of the narrowest portion 50P, and the same resistance is exhibited if the cross-sectional areas are similar. Even when the domain wall is moved to the position I2 or the position I3 by the spin current, there is a clear difference from the state where the domain wall exists at the position I01 or the position I02, and the information “1” and “0” can be determined.
FIG. 15 illustrates the case where there are two narrowest portions 50P, but the present invention is not limited to this, and there are three or more narrowest portions 50P, that is, four or more crystal grains 50A and 50B are connected. A magnetoresistive effect element having the connection portion 50 is also included in the scope of the present invention.

(Fifth embodiment)
Next, as a fifth embodiment of the present invention, a magnetic reproducing apparatus equipped with the magnetoresistive effect element 10 of the present invention will be described. That is, the magnetoresistive effect element 10 of the present invention described with reference to FIGS. 1 to 15 can be incorporated into a recording / reproducing integrated magnetic head assembly and mounted on a magnetic recording / reproducing apparatus, for example.

  FIG. 16 is a main part perspective view illustrating a schematic configuration of such a magnetic recording / reproducing apparatus. That is, the magnetic recording / reproducing apparatus 150 of the present invention is an apparatus using a rotary actuator. In the figure, a recording medium disk 180 is mounted on a spindle 152 and rotated in the direction of arrow A by a motor (not shown) that responds to a control signal from a drive device control unit (not shown). The magnetic recording / reproducing apparatus 150 of the present invention may be provided with a plurality of medium disks 180.

  A head slider 153 that records and reproduces information stored in the medium disk 180 is attached to the tip of a thin-film suspension 154. Here, the head slider 153 has, for example, the magnetoresistive effect element 10 according to any one of the above-described embodiments mounted near the tip thereof.

  When the medium disk 180 rotates, the medium facing surface (ABS) of the head slider 153 is held with a predetermined flying height from the surface of the medium disk 180. Alternatively, a so-called “contact traveling type” in which the slider contacts the medium disk 180 may be used.

  The suspension 154 is connected to one end of an actuator arm 155 having a bobbin portion for holding a drive coil (not shown). A voice coil motor 156, which is a kind of linear motor, is provided at the other end of the actuator arm 155. The voice coil motor 156 is composed of a drive coil (not shown) wound around the bobbin portion of the actuator arm 155, and a magnetic circuit composed of a permanent magnet and a counter yoke arranged so as to sandwich the coil.

  The actuator arm 155 is held by ball bearings (not shown) provided at two positions above and below the spindle 157, and can be freely rotated and slid by a voice coil motor 156.

  FIG. 17 is an enlarged perspective view of the magnetic head assembly ahead of the actuator arm 155 as viewed from the disk side. That is, the magnetic head assembly 160 includes an actuator arm 155 having, for example, a bobbin portion that holds a drive coil, and a suspension 154 is connected to one end of the actuator arm 155.

    A head slider 153 including any one of the magnetoresistive elements 10 described above with reference to FIGS. 1 to 15 is attached to the tip of the suspension 154. The suspension 154 has a lead wire 164 for writing and reading signals, and the lead wire 164 and each electrode of the magnetic head incorporated in the head slider 153 are electrically connected. In the figure, reference numeral 165 denotes an electrode pad of the magnetic head assembly 160.

  According to the present invention, by including the magnetoresistive effect element 10 of the present invention as described above with reference to FIGS. Can be read.

(Sixth embodiment)
Next, as a sixth embodiment of the present invention, a magnetic memory equipped with the magnetoresistive effect element 10 of the present invention will be described. That is, by using the magnetoresistive effect element 10 of the present invention described with reference to FIGS. 1 to 15, for example, a magnetic memory such as a random access magnetic memory in which memory cells are arranged in a matrix can be realized. .

  FIG. 18 is a conceptual diagram illustrating the matrix configuration of the magnetic memory of this embodiment.

  That is, this figure shows a circuit configuration of the embodiment when memory cells are arranged in an array. In order to select one bit in the array, a column decoder 350 and a row decoder 351 are provided, and the switching transistor 330 is turned on by the bit line 334 and the word line 332 to be uniquely selected and detected by the sense amplifier 352. Thereby, the bit information recorded in the magnetic recording layer constituting the magnetoresistive element 10 can be read.

  The bit information is written by a magnetic field generated by supplying a write current to the specific write word line 323 and the bit line 322.

  FIG. 19 is a conceptual diagram showing another specific example of the matrix configuration of the magnetic memory of this embodiment. That is, in the case of this specific example, the bit lines 322 and the word lines 334 wired in a matrix are selected by the decoders 360 and 361, respectively, and specific memory cells in the array are selected. Each memory cell has a structure in which a magnetoresistive element 10 and a diode D are connected in series. Here, the diode D has a role of preventing the sense current from bypassing in the memory cells other than the selected magnetoresistive effect element 10.

  Writing is performed by a magnetic field generated by supplying a write current to the specific bit line 322 and the write word line 323, respectively.

The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to the specific examples described above. For example, a combination of any two or more of the specific examples described above with reference to FIGS. 1 to 19 is included in the scope of the present invention.
That is, the present invention is not limited to the specific examples, and various modifications can be made without departing from the spirit of the present invention, and all of these are included in the scope of the present invention.

It is a conceptual diagram showing the planar structure of the magnetoresistive effect element concerning embodiment of this invention. It is a schematic diagram showing the magnetoresistive effect element of 1st Example of this invention. It is a principal part schematic diagram for demonstrating the magnetoresistive effect in the magnetoresistive effect element 10 of a present Example. It is a process perspective view showing the manufacturing method of the magnetoresistive effect element of a present Example. It is a process perspective view showing the manufacturing method of the magnetoresistive effect element of a present Example. It is a process perspective view showing the manufacturing method of the magnetoresistive effect element of a present Example. It is a graph showing the characteristic acquired in the magnetoresistive effect element which this inventor made as an experiment. It is a schematic diagram for demonstrating the migration effect. It is a schematic diagram showing the modification of the magnetoresistive effect element of this embodiment. It is the model showing the magnetoresistive effect element of the 2nd Example of this invention, (a) is the perspective view, (b) is a top view of the principal part. It is a schematic diagram for demonstrating operation | movement of the magnetoresistive effect element of a present Example. It is a schematic diagram showing the memory which arranged the magnetoresistive effect element in the array form. It is process drawing showing the manufacturing method of the memory array of a present Example. It is process drawing showing the manufacturing method of the memory array of a present Example. It is a schematic diagram showing the magnetoresistive effect element of the 4th Example of this invention. It is a principal part perspective view which illustrates schematic structure of a magnetic recording / reproducing apparatus. 5 is an enlarged perspective view of the magnetic head assembly ahead of the actuator arm 155 as viewed from the disk side. FIG. It is a conceptual diagram which illustrates the matrix structure of the magnetic memory of a present Example. It is a conceptual diagram showing the other specific example of the matrix structure of the magnetic memory of a present Example.

Explanation of symbols

 10 magnetoresistive effect element, 20 base, 20B bridge, 30 first ferromagnetic layer, 40 second ferromagnetic layer, 50 connection part, 50A, 50B, 50C crystal grain, 50M magnetization, 50P narrowest part, 60 antiferromagnetic layer, 70 electrode, 80 antiferromagnetic layer, 100 ferromagnetic layer, 150 magnetic recording / reproducing apparatus, 152 spindle, 153 head slider, 154 suspension, 155 actuator arm, 156 voice coil motor, 157 spindle , 160 magnetic head assembly, 164 lead wire, 180 media disk, 200 mask, 300 focused ion beam, 322 bit line, 323 word line, 330 switching transistor, 332 word line, 334 bit line, 334 word line, 350 column decoder, 351 row decoder, 3 Second sense amplifier, 360 a decoder, 500 an ion beam, 600 target

Claims (17)

An insulating base,
A first ferromagnetic layer provided on the main surface of the base;
A second ferromagnetic layer provided apart from the first ferromagnetic layer on the main surface of the base;
A connecting portion provided on and in contact with the first ferromagnetic layer and the second ferromagnetic layer on the main surface of the base, the first ferromagnetic layer being made of a ferromagnetic material. A narrowest portion of a path of a current flowing between the first ferromagnetic layer and the second ferromagnetic layer having a crystal grain and a second crystal grain made of a ferromagnetic material. A connection part that is a crystal grain boundary between the first crystal grain and the second crystal grain;
A magnetoresistive effect element comprising: An insulating base,
A first ferromagnetic layer provided on the main surface of the base;
A second ferromagnetic layer provided apart from the first ferromagnetic layer on the main surface of the base;
A plurality of crystals made of a ferromagnetic material, a connecting portion provided on and in contact with the first ferromagnetic material layer and the second ferromagnetic material layer on the main surface of the base The narrowest part of the path of the current flowing between the first ferromagnetic layer and the second ferromagnetic layer having a grain is a grain boundary;
A magnetoresistive effect element comprising: An insulating base,
A first ferromagnetic layer provided on the main surface of the base;
A second ferromagnetic layer provided apart from the first ferromagnetic layer on the main surface of the base;
A connecting portion provided on and in contact with the first ferromagnetic layer and the second ferromagnetic layer on the main surface of the base, the first ferromagnetic layer being made of a ferromagnetic material. A crystal grain and a second crystal grain made of a ferromagnetic material, and the magnetization direction of the first ferromagnetic layer is different from the magnetization direction of the second ferromagnetic layer, A connection portion in which a domain wall is formed at a grain boundary between the first crystal grain and the second crystal grain;
A magnetoresistive effect element comprising: An insulating base,
A first ferromagnetic layer provided on the main surface of the base;
A second ferromagnetic layer provided apart from the first ferromagnetic layer on the main surface of the base;
A connecting portion provided on and in contact with the first ferromagnetic layer and the second ferromagnetic layer on the main surface of the base, the first ferromagnetic layer; And a plurality of crystal grains formed by depositing a ferromagnetic material on the main surface of the base between the first ferromagnetic material layer and the second ferromagnetic material layer, and the first ferromagnetic material layer and the second ferromagnetic material layer The narrowest part of the path of the current flowing between the second ferromagnetic layer is a crystal grain boundary,
A magnetoresistive effect element comprising: The underlayer includes a groove provided between the first ferromagnetic layer and the second ferromagnetic layer, and the first ferromagnetic layer and the second ferromagnetic layer. A bridge adjacent to the groove in between,
The magnetoresistive effect element according to claim 1, wherein the connection portion is provided on the bridge.   The magnetoresistive effect element according to claim 1, wherein the crystal grain boundary contains a nonmagnetic element.   6. The magnetoresistive according to claim 1, wherein a cross-sectional area of a current path passing through the crystal grain boundary changes discontinuously before and after the crystal grain boundary. Effect element.   A first antiferromagnetic layer or a first hard magnetic layer, which is laminated on the first ferromagnetic layer and fixes the magnetization of the first ferromagnetic layer, is further provided. Item 8. The magnetoresistive element according to any one of Items 1 to 7.   A second antiferromagnetic layer stacked on the second ferromagnetic layer and fixing the magnetization of the second ferromagnetic layer in a direction opposite to the magnetization of the first ferromagnetic layer, or 9. The magnetoresistive element according to claim 8, further comprising a second hard magnetic layer. Forming a first ferromagnetic layer and a second ferromagnetic layer on the main surface of the insulating base;
A ferromagnetic material is deposited on the main surface of the base between the first ferromagnetic layer and the second ferromagnetic layer, and the first ferromagnetic layer and the second strong layer are deposited. A method of manufacturing a magnetoresistive effect element, comprising forming a connection portion for electrically connecting a magnetic layer. Forming a groove in the base between the first ferromagnetic layer and the second ferromagnetic layer;
The method of manufacturing a magnetoresistive effect element according to claim 10, wherein the connection portion is formed on the main surface adjacent to the groove. Forming a first layer made of a ferromagnetic material on a main surface of an insulating base;
Selectively removing the first layer and at least a portion of the underlying layer;
By further selectively removing the first layer, the first ferromagnetic layer and the second ferromagnetic layer are separated,
A ferromagnetic material is deposited on the main surface between the first ferromagnetic material layer and the second ferromagnetic material layer, and the first ferromagnetic material layer and the second ferromagnetic material layer are deposited. A method of manufacturing a magnetoresistive effect element, characterized in that a connection portion for electrically connecting the two is formed.   13. The step of separating the first ferromagnetic layer and the second ferromagnetic layer and the step of forming the connection portion are performed while maintaining a reduced pressure atmosphere. Manufacturing method of the magnetoresistive effect element.   The magnetoresistive effect according to claim 12 or 13, wherein the step of separating the first ferromagnetic layer and the second ferromagnetic layer and the step of forming the connection portion are repeated. Device manufacturing method.   A magnetoresistive effect element according to claim 1, wherein writing and reading are performed by passing a current between the first ferromagnetic layer and the second ferromagnetic layer. A magnetic memory characterized by performing at least one of them.   10. A magnetic head comprising the magnetoresistive element according to claim 1 and capable of reading information magnetically recorded on a magnetic recording medium. A magnetic recording apparatus comprising the magnetic head according to claim 16.

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