JP6485588B1 - How to write data - Google Patents

Abstract

A data writing method capable of stably writing data to a magnetic memory is provided.
A data writing method according to the present invention includes a spin orbit torque wiring extending in a first direction and a first ferromagnetic layer stacked on one surface of the spin orbit torque wiring from the spin orbit torque wiring side. A spin orbit torque type magnetoresistive effect element including a nonmagnetic layer and a second ferromagnetic layer, and a voltage applied in the first direction of the spin orbit torque wiring is set to a critical temperature at an environmental temperature. The write voltage is not less than a predetermined value and not more than a predetermined value. When the environmental temperature is −40 ° C., 20 ° C., and 100 ° C., the write error rate when reversing the magnetization of the first ferromagnetic layer is the critical write voltage. This is the limit write voltage that is equal to the write error rate when.
[Selection figure] None

Description

  The present invention relates to a data writing method.

  A giant magnetoresistive (GMR) element composed of a multilayer film of a ferromagnetic layer and a nonmagnetic layer as an element utilizing a resistance value change (magnetoresistive change) based on a change in relative angle of magnetization of two ferromagnetic layers, and A tunnel magnetoresistive (TMR) element using an insulating layer (tunnel barrier layer, barrier layer) as a nonmagnetic layer is known.

  The MRAM reads and writes data using the characteristic that the element resistance of the GMR element or the TMR element changes when the directions of magnetization of the two ferromagnetic layers sandwiching the insulating layer change. As a writing method of the MRAM, writing (magnetization reversal) is performed using a magnetic field generated by current, and writing (magnetization) is performed using spin transfer torque (STT) generated by flowing current in the stacking direction of the magnetoresistive effect element. A method of performing inversion) is known.

  In the magnetization reversal of the magnetoresistive effect element using the STT, it is necessary to pass a current in the stacking direction of the magnetoresistive effect element when writing data. The write current may degrade the characteristics of the magnetoresistive element.

  Therefore, in recent years, attention has been focused on a method that does not require a current to flow in the stacking direction of the magnetoresistive effect element at the time of writing. One method is a writing method using spin orbit torque (SOT) (for example, Non-Patent Document 1). SOT is induced by a pure spin current generated by spin orbit interaction or a Rashba effect at the interface between different materials. A current for inducing SOT in the magnetoresistive effect element flows in a direction crossing the stacking direction of the magnetoresistive effect element. That is, there is no need to pass a current in the stacking direction of the magnetoresistive effect element, and the life of the magnetoresistive effect element is expected to be extended.

S.Fukami, T.Anekawa, C.Zhang and H.Ohno, Nature Nano Tec (2016) .DOI: 10.1038 / NNANO.2016.29.

In the magnetic memory, the magnetoresistive effect element records data. In order to sufficiently ensure the reliability of recorded data, the write error rate of the magnetoresistive effect element is required to be 10 ⁻⁷ or less.

  As described above, the spin orbit torque type magnetoresistive effect element that writes data using SOT does not pass a current in the stacking direction of the magnetoresistive effect element. Therefore, there is almost no need to consider the dielectric breakdown of the magnetoresistive effect element, and a large write current can be flowed in principle. As the amount of write current applied increases, a large number of spins are injected into the ferromagnetic material into the magnetoresistive element. That is, it has been considered that the write error rate of the magnetoresistive element can be further reduced by flowing a large write current.

  However, as a result of intensive studies, the present inventors have found that the write error rate of the magnetoresistive element deteriorates when a predetermined voltage value or current value is applied even if it is a spin orbit torque type magnetoresistive element. I found.

  The present invention has been made in view of the above circumstances, and provides a data writing method capable of stably writing data to a magnetic memory. A magnetic memory capable of stably writing data is provided.

That is, this invention provides the following means in order to solve the said subject.

(1) A data writing method according to the first aspect includes a spin orbit torque wiring extending in a first direction and a layer on one surface of the spin orbit torque wiring, and the first strong orbit from the spin orbit torque wiring side. In a spin orbit torque type magnetoresistive effect element including a functional portion including a magnetic layer, a nonmagnetic layer, and a second ferromagnetic layer, a voltage applied in the first direction of the spin orbit torque wiring is set to an environmental temperature. The predetermined write value is not less than a predetermined value and not more than a predetermined value. When the ambient temperature is −40 ° C., 20 ° C., and 100 ° C., the write error rate when reversing the magnetization of the first ferromagnetic layer is The limit write voltage that is equal to the write error rate when the write voltage is applied, and the limit write at −40 ° C. in the temperature region where the ambient temperature is less than 20 ° C. The voltage is located on a straight line connecting the pressure and the limit writing voltage at 20 ° C., and in a temperature region where the environmental temperature is 20 ° C. or higher, on the line connecting the limit writing voltage at 20 ° C. and the limit writing voltage at 100 ° C. Is the voltage located at.

(2) In the data writing method according to the above aspect, when the environmental temperature is in the temperature range of 20 ° C. or higher, 1.01 times the critical write voltage at 20 ° C. in the first direction of the spin orbit torque wiring. When the above voltage is applied at the time of data writing, and the environmental temperature is in a temperature range of less than 20 ° C., a voltage that is 1.05 times or more the critical write voltage at 20 ° C. in the first direction of the spin orbit torque wiring. May be applied at the time of data writing.

(3) In the data writing method according to the above aspect, when the environmental temperature is 20 ° C. or higher, the critical write voltage at 20 ° C. or higher in the first direction of the spin orbit torque wiring in the first direction. Is applied at the time of data writing, and when the environmental temperature is less than 20 ° C., the critical write voltage at the environmental temperature is higher than the critical write voltage at the environmental temperature in the first direction of the spin orbit torque wiring. You may apply the voltage 1.54 times or less of the writing voltage at the time of data writing.

(4) In the data writing method according to the above aspect, when data is written in a temperature range of −40 ° C. or higher and 100 ° C. or lower, a critical write voltage of 1.2 is applied in the first direction of the spin orbit torque wiring. You may apply the voltage more than twice and below 1.54 times.

(5) In the method of writing data according to the above embodiment, a the spin-orbit torque wiring tungsten, the predetermined value V, when the threshold write voltage at 20 ° C. V _0, the environmental temperature was set to t (° C.) In the temperature region where the environmental temperature is less than 20 ° C., V = (2.0 × 10 ⁻³ × t + 1.62) × Vo is satisfied, and in the temperature region where the environmental temperature is 20 ° C. or higher, V = (1 .3 × 10 ⁻³ × t + 1.635) × Vo may be satisfied.

(6) In the method of writing data according to the above embodiment, a the spin-orbit torque wiring tantalum, the predetermined value V is the threshold write voltage at 20 ° C. V _0, when the environmental temperature was set to t (° C.) In the temperature region where the environmental temperature is less than 20 ° C., V = (0.8 × 10 ⁻³ × t + 1.63) × Vo is satisfied, and in the temperature region where the environmental temperature is 20 ° C. or higher, V = 1. It may satisfy 65 × Vo.

(7) In the method of writing data according to the above embodiment, a the spin-orbit torque wiring iridium, the predetermined value V is the threshold write voltage at 20 ° C. V _0, when the environmental temperature was set to t (° C.) In the temperature region where the environmental temperature is less than 20 ° C., V = (0.2 × 10 ⁻³ × t + 1.7167) × Vo is satisfied, and in the temperature region where the environmental temperature is 20 ° C. or higher, V = (1 .9 × 10 ⁻³ × t + 1.6825) × Vo may be satisfied.

(8) In the method of writing data according to the above embodiment, the a spin-orbit torque wiring platinum, the predetermined value V is the threshold write voltage at 20 ° C. V _0, when the environmental temperature was set to t (° C.) In the temperature region where the environmental temperature is less than 20 ° C., V = (0.8 × 10 ⁻³ × t + 1.6333) × Vo is satisfied, and in the temperature region where the environmental temperature is 20 ° C. or higher, V = (0 .3 × 10 ⁻³ × t + 1.645) × Vo may be satisfied.

(9) A magnetic memory according to a second aspect is formed by stacking a spin orbit torque wiring extending in a first direction and one surface of the spin orbit torque wiring, and the first ferromagnetic layer from the spin orbit torque wiring side. A voltage source connected to the spin orbit torque wiring and capable of applying a voltage not lower than a critical write voltage at an ambient temperature and not higher than a predetermined value in the first direction, and a functional unit including a nonmagnetic layer and a second ferromagnetic layer; When the environmental temperature is −40 ° C., 20 ° C., and 100 ° C., the write error rate when reversing the magnetization of the first ferromagnetic layer is applied when the critical write voltage is applied. In the temperature region where the ambient temperature is less than 20 ° C., the limit write voltage at −40 ° C. and the limit write voltage at 20 ° C. are connected. A voltage located on the straight line, in the temperature range of the ambient temperature is 20 ° C. or higher, a voltage located on the straight line connecting the limit writing voltage at the limit writing voltage and 100 ° C. at 20 ° C..

(10) The magnetic memory according to the above aspect may further include a thermometer connected to the spin orbit torque wiring and converting the temperature of the spin orbit torque wiring from a resistance value of the spin orbit torque wiring.

  According to the data writing method and the magnetic memory according to the present embodiment, data can be stably written.

It is a schematic diagram of the magnetic memory concerning this embodiment. It is the figure which showed the change of MR ratio of a functional part when the write voltage value applied to the x direction of a spin orbit torque wiring is changed. It is a schematic diagram of another example of the magnetic memory according to the present embodiment. 6 shows changes in the write error rate of the magnetic memory of Example 1 when the applied voltage value of the write pulse is changed. 6 shows changes in the write error rate of the magnetic memory of Example 1 when the applied voltage value of the write pulse is changed. The change of the write error rate of the magnetic memory of Example 6 when changing the applied voltage value of the write pulse is shown. The change of the write error rate of the magnetic memory of Example 6 when changing the applied voltage value of the write pulse is shown. The change of the write error rate of the magnetic memory of Example 9 when changing the applied voltage value of the write pulse is shown. The change of the write error rate of the magnetic memory of Example 9 when changing the applied voltage value of the write pulse is shown. The change of the write error rate of the magnetic memory of Example 12 when changing the applied voltage value of the write pulse is shown. The change of the write error rate of the magnetic memory of Example 12 when changing the applied voltage value of the write pulse is shown.

  Hereinafter, the present embodiment will be described in detail with appropriate reference to the drawings. In the drawings used in the following description, in order to make the features easier to understand, the portions that become the features may be shown in an enlarged manner for the sake of convenience, and the dimensional ratios of the respective components may differ from the actual ones. The materials, dimensions, and the like exemplified in the following description are merely examples, and the present invention is not limited to these, and can be implemented with appropriate modifications within the scope of the effects of the present invention.

(Magnetic memory)
FIG. 1 is a schematic diagram of a magnetic memory 100 according to the present embodiment. The magnetic memory 100 includes a spin orbit torque type magnetoresistance effect element 10 and a voltage source 20.

<Spin orbit torque type magnetoresistive effect element>
The spin orbit torque type magnetoresistive effect element 10 includes a functional unit 1 and a spin orbit torque wiring 2. A conductive first electrode 3 and a second electrode 4 are provided at positions sandwiching the functional unit 1 of the spin orbit torque wiring 2. The first electrode 3 and the second electrode 4 may be directly connected to the spin orbit torque wiring 2 or may be connected via an insulating layer. When these are directly connected to the spin orbit torque wiring 2, current driving is performed, and when these are connected to the spin orbit torque wiring 2 via an insulator, voltage driving is performed.
Hereinafter, the first direction in which the spin orbit torque wiring 2 extends is the x direction, the stacking direction (second direction) of the functional unit 1 is the z direction, and the direction perpendicular to both the x direction and the z direction is the y direction. It is prescribed and explained.

[Spin orbit torque wiring]
The spin orbit torque wiring 2 extends in the x direction. The spin orbit torque wiring 2 is connected to one surface of the functional unit 1 in the z direction. The spin orbit torque wiring 2 may be directly connected to the functional unit 1 or may be connected via another layer.

  The spin orbit torque wiring 2 is made of a material that generates a spin current by the spin Hall effect when the current I flows. As such a material, any material that can generate a spin current in the spin orbit torque wiring 2 is sufficient. Therefore, the material is not limited to a material composed of a single element, and may be composed of a portion composed of a material that easily generates a spin current and a portion composed of a material that hardly generates a spin current.

  The spin Hall effect is a phenomenon in which a spin current is induced in a direction orthogonal to the direction of the current I based on the spin-orbit interaction when a current I is passed through the material. The mechanism by which spin current is generated by the spin Hall effect will be described.

  When a potential difference is applied to both ends of the spin orbit torque wiring 2, a current I flows along the spin orbit torque wiring 2. When the current I flows, the first spin S1 oriented in one direction and the second spin S2 oriented in the opposite direction to the first spin S1 are bent in directions orthogonal to the current, respectively. For example, the first spin S1 is bent in the z direction with respect to the traveling direction, and the second spin S2 is bent in the -z direction with respect to the traveling direction.

  The normal Hall effect and the spin Hall effect are common in that the moving (moving) charge (electrons) can bend in the moving (moving) direction. On the other hand, in the normal Hall effect, charged particles moving in a magnetic field receive the Lorentz force and bend the direction of movement, whereas in the Spin Hall effect, electrons move only even when no magnetic field exists (currents). The only difference is that the spin movement direction is bent.

  Since the number of electrons of the first spin S1 is equal to the number of electrons of the second spin S2 in a non-magnetic material (a material that is not a ferromagnetic material), the number of electrons of the first spin S1 toward the + z direction and the −z direction in the figure. The number of electrons of the second spin S2 going to is equal. In this case, the charge flows cancel each other, and the amount of current becomes zero. A spin current without an electric current is particularly called a pure spin current.

  When the electron flow of the first spin S1 is J ↑, the electron flow of the second spin S2 is J ↓, and the spin current is JS, JS = J ↑ −J ↓ is defined. The spin current JS flows in the z direction in the figure. In FIG. 1, a first ferromagnetic layer 1 </ b> A described later is present on the upper surface of the spin orbit torque wiring 2. Therefore, spin is injected into the first ferromagnetic layer 1A.

  The spin orbit torque wiring 2 is made of any one of a metal, an alloy, an intermetallic compound, a metal boride, a metal carbide, a metal silicide, and a metal phosphide having a function of generating a spin current by a spin Hall effect when a current flows. Composed.

  The main configuration of the spin orbit torque wiring 2 is preferably a nonmagnetic heavy metal. Here, the heavy metal means a metal having a specific gravity equal to or higher than yttrium. The nonmagnetic heavy metal is preferably a nonmagnetic metal having an atomic number of 39 or more having d electrons or f electrons in the outermost shell. These nonmagnetic metals have a large spin-orbit interaction that causes a spin Hall effect.

  Electrons generally move in the opposite direction of current, regardless of their spin direction. On the other hand, a nonmagnetic metal having d electrons or f electrons in the outermost shell and having a large atomic number has a large spin orbit interaction and a strong spin Hall effect. For this reason, the direction in which electrons move depends on the direction of spin of electrons. Therefore, spin current JS is likely to occur in these nonmagnetic heavy metals.

  Further, the spin orbit torque wiring 2 may include a magnetic metal. The magnetic metal refers to a ferromagnetic metal or an antiferromagnetic metal. If a non-magnetic metal contains a trace amount of magnetic metal, it becomes a spin scattering factor. When the spin is scattered, the spin-orbit interaction is enhanced, and the generation efficiency of the spin current with respect to the current is increased. The main configuration of the spin orbit torque wiring 2 may be composed only of an antiferromagnetic metal.

  On the other hand, if the amount of magnetic metal added is excessively increased, the generated spin current may be scattered by the added magnetic metal, and as a result, the effect of decreasing the spin current may become stronger. Therefore, the molar ratio of the magnetic metal added is preferably sufficiently smaller than the total molar ratio of the elements constituting the spin orbit torque wiring. The molar ratio of the magnetic metal to be added is preferably 3% or less.

  The spin orbit torque wiring 2 may include a topological insulator. A topological insulator is a substance in which the inside of the substance is an insulator or a high-resistance substance, but a spin-polarized metal state is generated on the surface thereof. This material generates an internal magnetic field due to spin-orbit interaction. Therefore, even without an external magnetic field, a new topological phase appears due to the effect of spin-orbit interaction. This is a topological insulator, and a pure spin current can be generated with high efficiency by strong spin-orbit interaction and breaking inversion symmetry at the edge.

Examples of the topological insulator include SnTe, Bi _1.5 Sb _0.5 Te _1.7 Se _1.3 , TlBiSe ₂ , Bi ₂ Te ₃ , Bi _1-x Sb _x , (Bi _1-x Sb _x ) _2. Te _{3 and the} like are preferable. These topological insulators can generate a spin current with high efficiency.

[Function section]
The functional unit 1 includes a first ferromagnetic layer 1A, a second ferromagnetic layer 1B, and a nonmagnetic layer 1C sandwiched between them. The functional unit 1 is stacked in a second direction (z direction) intersecting with the spin orbit torque wiring 2.

  The functional unit 1 changes its resistance value by changing the relative angle between the magnetization M1A of the first ferromagnetic layer 1A and the magnetization M1B of the second ferromagnetic layer 1B. The magnetization M1B of the second ferromagnetic layer 1B is fixed in one direction (z direction), and the direction of the magnetization M1A of the first ferromagnetic layer 1A changes relative to the magnetization M1B. The second ferromagnetic layer 1B may be referred to as a fixed layer, a reference layer, or the like, and the first ferromagnetic layer 1A may be referred to as a free layer, a recording layer, or the like. When applied to a coercive force difference type (pseudo spin valve type) MRAM, the coercivity of the second ferromagnetic layer 1B is made larger than the coercivity of the first ferromagnetic layer 1A. When applied to an exchange bias type (spin valve type) MRAM, the magnetization M1B of the second ferromagnetic layer 1B is fixed by exchange coupling with the antiferromagnetic layer.

  When the nonmagnetic layer 1C is made of an insulator, the functional unit 1 has the same configuration as a tunneling magnetoresistive (TMR) element. When the nonmagnetic layer 1C is made of a metal, the giant magnetoresistive (GMR) The configuration is the same as that of the element.

  The laminated structure of the functional unit 1 can employ a known laminated structure of magnetoresistive elements. For example, each layer may be composed of a plurality of layers, or may be provided with other layers such as an antiferromagnetic layer for fixing the magnetization direction of the second ferromagnetic layer 1B. The second ferromagnetic layer 1B is called a fixed layer or a reference layer, and the first ferromagnetic layer 1A is called a free layer or a storage layer.

  The first ferromagnetic layer 1A and the second ferromagnetic layer 1B are either a perpendicular magnetization film in which the magnetization easy axes of the magnetizations M1A and M1B are oriented in the z direction, or an in-plane magnetization film in which the easy magnetization axis is oriented in the xy in-plane direction. Good.

A ferromagnetic material can be applied to the first ferromagnetic layer 1A and the second ferromagnetic layer 1B. For example, a metal selected from the group consisting of Cr, Mn, Co, Fe, and Ni, an alloy containing one or more of these metals, these metals and at least one element of B, C, and N are included. Alloys that can be used can be used. Specifically, Co—Fe, Co—Fe—B, and Ni—Fe can be exemplified. When the first ferromagnetic layer 1A is an in-plane magnetization film, it is preferable to use, for example, a Co—Ho alloy (CoHo ₂ ), an Sm—Fe alloy (SmFe ₁₂ ), or the like.

When a Heusler alloy such as Co2FeSi is used for at least one of the first ferromagnetic layer 1A and the second ferromagnetic layer 1B, the magnetoresistance effect is more strongly expressed. The Heusler alloy includes an intermetallic compound having a chemical composition of X2YZ, where X is a Co, Fe, Ni, or Cu group transition metal element or noble metal element on the periodic table, and Y is Mn, V, Cr. Alternatively, it is a Ti group transition metal or X element species, and Z is a typical element from Group III to Group V. For _{example, Co 2 FeSi, Co 2 FeGe} , Co 2 FeGa, Co 2 MnSi, Co 2 Mn 1-a Fe a Al b Si 1-b, Co 2 FeGe 1-c Ga c , and the like.

  A layer made of an antiferromagnetic material such as IrMn or PtMn may be laminated on the second ferromagnetic layer 1B. By adopting a synthetic ferromagnetic coupling structure, the influence of the leakage magnetic field of the second ferromagnetic layer 1B on the first ferromagnetic layer 1A can be reduced.

A known material can be used for the nonmagnetic layer 1C.
For example, when the nonmagnetic layer 1C is made of an insulator (when it is a tunnel barrier layer), as the material, Al ₂ O ₃ , SiO ₂ , MgO, MgAl ₂ O _4, or the like can be used. In addition to these, a material in which a part of Al, Si, Mg is substituted with Zn, Be, or the like can also be used. Among these, since MgO and MgAl ₂ O ₄ are materials that can realize a coherent tunnel, spin can be injected efficiently. When the nonmagnetic layer 1C is made of a metal, Cu, Au, Ag, or the like can be used as the material thereof. Further, when the nonmagnetic layer 1C is made of a semiconductor, Si, Ge, CuInSe ₂ , CuGaSe ₂ , Cu (In, Ga) Se ₂ or the like can be used as the material.

  The functional unit 1 may have other layers. An underlayer may be provided on the surface of the first ferromagnetic layer 1A opposite to the nonmagnetic layer 1C. It is preferable that the layer disposed between the spin orbit torque wiring 2 and the first ferromagnetic layer 1 </ b> A does not dissipate the spin propagating from the spin orbit torque wiring 2. For example, it is known that silver, copper, magnesium, aluminum, and the like have a long spin diffusion length of 100 nm or more and are difficult to dissipate spin. The thickness of this layer is preferably less than or equal to the spin diffusion length of the material constituting the layer. If the thickness of the layer is less than or equal to the spin diffusion length, the spin propagating from the spin orbit torque wiring 2 can be sufficiently transmitted to the first ferromagnetic layer 1A.

<Voltage source>
The voltage source 20 is connected to the spin orbit torque wiring 2 and applies a voltage in the x direction of the spin orbit torque wiring 2. The voltage source 20 may be directly connected to the spin orbit torque wiring 2 or may be indirectly connected as long as a voltage can be applied in the x direction of the spin orbit torque wiring 2.

  The voltage source 20 applies a voltage that is greater than or equal to the critical write voltage at the ambient temperature and less than or equal to a predetermined value in the x direction of the spin orbit torque wiring 2 during data write. Here, the environmental temperature is the temperature of the spin orbit torque type magnetoresistive effect element 10, and more specifically, the temperature of the spin orbit torque wiring 2.

The critical write voltage V ₀ is obtained by the following relational expression.

When a critical write voltage V ₀ is applied to the spin torque orbit wiring 2, a write error rate generated in the function unit 1 (when the magnetization M 1 A of the first ferromagnetic layer 1 A of the function unit 1 is reversed, the magnetization is performed in a desired direction. The probability that M1A is not oriented and a write error occurs) is in the range of 10 ⁻³ to 10 ⁻⁴ . In this specification, the write error rate when a critical write voltage is applied is 10 ⁻³ . Since the magnetic anisotropy of the first ferromagnetic layer 1A varies depending on the temperature, and the resistance value of the spin orbit torque wiring 2 also varies depending on the temperature, the critical write voltage varies depending on the environmental temperature.

  Although the critical write voltage at the environmental temperature, which is the lower limit value that can be applied by the voltage source 20, may be measured at each temperature, the critical write voltage in other temperature ranges from the critical write voltage at −40 ° C., 20 ° C., and 100 ° C. An approximate value may be calculated.

  First, critical writing voltages at −40 ° C., 20 ° C., and 100 ° C. are obtained. Each critical write voltage is plotted on a graph with the horizontal axis representing temperature and the vertical axis representing voltage. The plotted critical writing voltage value at −40 ° C. and the critical writing voltage value at 20 ° C. are connected by a straight line. Similarly, the plotted critical writing voltage value at 20 ° C. and the critical writing voltage value at 100 ° C. are connected by a straight line. The voltage located on these lines can be used as the estimated critical write voltage at each temperature. That is, the estimated critical write voltage is a voltage located on a straight line connecting the critical write voltage at −40 ° C. and the critical write voltage at 20 ° C. in a temperature range higher than −40 ° C. and lower than 20 ° C. In the temperature range higher than 20 ° C. and lower than 100 ° C., it is on a straight line connecting the critical write voltage at 20 ° C. and the critical write voltage at 100 ° C.

  The predetermined value that is the upper limit value that can be applied by the voltage source 20 satisfies the following relationship.

When the ambient temperature is −40 ° C., 20 ° C., and 100 ° C., the predetermined value is the write error rate when the critical write voltage V ₀ is applied as the write error rate when reversing the magnetization M1A of the first ferromagnetic layer 1A. This is the limit writing voltage equal to the rate (10 ⁻³ ).

  In the temperature range where the environmental temperature is less than 20 ° C., the predetermined value is a voltage located on a straight line connecting the limit write voltage at −40 ° C. and the limit write voltage at 20 ° C.

  In the temperature region where the environmental temperature is 20 ° C. or higher, the predetermined value is a voltage located on a straight line connecting the limit write voltage at 20 ° C. and the limit write voltage at 100 ° C.

  In the magnetic memory 100 that writes data using SOT, the voltage value applied in the x direction of the spin orbit torque wiring 2 has no upper limit in principle. If a large voltage is applied, a large write current can be passed through the spin orbit torque wiring 2, and in principle, the write error rate of the magnetoresistive effect element can be further reduced.

  However, if the voltage value applied in the x direction of the spin orbit torque wiring 2 is actually varied, data cannot be stably recorded when a voltage higher than a predetermined voltage value is applied. That is, it has been found that there is an upper limit value (limit writing voltage) of the voltage that can be applied.

  FIG. 2 is a diagram showing a change in MR ratio of the functional unit (magnetoresistance effect element) 1 when the write voltage value applied in the x direction of the spin orbit torque wiring 2 is changed. The MR ratio shown here is (R−Rp) / Rp, R is the measured resistance value, and Rp is the magnetization M1A of the first ferromagnetic layer 1A and the magnetization M1B of the second ferromagnetic layer 1B. Theoretical resistance value in the case of complete equilibrium.

  As shown in FIG. 2, when the voltage value applied in the x direction of the spin orbit torque wiring 2 is increased to around 0.05 V, the MR ratio increases rapidly. This change means that the magnetization M1A of the first ferromagnetic layer 1A and the magnetization M1B of the second ferromagnetic layer 1B have shifted from the equilibrium state to the anti-equilibrium state. That is, it means that data has been written by applying a voltage of a predetermined value or more.

  On the other hand, when the voltage value applied in the x direction of the spin orbit torque wiring 2 is increased to near 0.08 V, the MR ratio starts to vibrate between a high state and a low state. Despite the application of the write voltage so that the magnetization M1A of the first ferromagnetic layer 1A and the magnetization M1B of the second ferromagnetic layer 1B are in an anti-equilibrium state, between the equilibrium state and the anti-equilibrium state The state is no longer stabilized. That is, when a voltage higher than a predetermined value is applied, data cannot be recorded stably.

  In other words, as shown in FIG. 2, when a voltage of a predetermined value or less is applied in the x direction of the spin orbit torque wiring 2, data can be stably written in the magnetic memory 100.

  When the environmental temperature is 20 ° C. or higher, the predetermined value that is the upper limit value that can be applied by the voltage source 20 is preferably a voltage that is not lower than the critical write voltage at the environmental temperature and not higher than 1.65 times the critical write voltage at 20 ° C. When the environmental temperature is less than 20 ° C., the voltage is preferably not less than the critical writing voltage at the environmental temperature and not more than 1.54 times the critical writing voltage at 20 ° C.

When the spin orbit torque wiring 2 is tungsten, the predetermined value V satisfies V = (2.0 × 10 ⁻³ × t + 1.62) × Vo in the temperature range where the environmental temperature is less than 20 ° C. In the temperature region where the temperature is 20 ° C. or higher, it is preferable to satisfy V = (1.3 × 10 ⁻³ × t + 1.635) × Vo.

When the spin orbit torque wiring 2 is tantalum, the predetermined value V satisfies V = (0.8 × 10 ⁻³ × t + 1.63) × Vo in the temperature region where the environmental temperature is less than 20 ° C. In the temperature region where the temperature is 20 ° C. or higher, it is preferable to satisfy V = 1.65 × Vo.

When the spin orbit torque wiring 2 is iridium, the predetermined value V satisfies V = (0.2 × 10 ⁻³ × t + 1.7167) × Vo in the temperature range where the environmental temperature is less than 20 ° C. In the temperature region where the temperature is 20 ° C. or higher, it is preferable to satisfy V = (1.9 × 10 ⁻³ × t + 1.6825) × Vo.

When the spin orbit torque wiring 2 is platinum, the predetermined value V satisfies V = (0.8 × 10 ⁻³ × t + 1.6333) × Vo in the temperature range where the environmental temperature is less than 20 ° C. In the temperature region where the temperature is 20 ° C. or higher, it is preferable to satisfy V = (0.3 × 10 ⁻³ × t + 1.645) × Vo.

In the above relational expression, V ₀ is a critical write voltage at 20 ° C., and t is an environmental temperature (° C.).

  Further, when writing data in a temperature region of 20 ° C. or higher, it is preferable to apply a voltage of 1.01 times or more of the critical write voltage in the x direction of the spin orbit torque wiring 2 and 1.08 of the critical write voltage. It is more preferable to apply a voltage that is twice or more, and it is even more preferable to apply a voltage that is 1.15 or more times the critical writing voltage. When writing data in a temperature range below 20 ° C., it is preferable to apply a voltage of 1.05 times or more the critical write voltage in the x direction of the spin orbit torque wiring 2. Moreover, it is preferable that the voltage source 20 can apply these voltages.

  If a voltage exceeding the critical write voltage can be applied in the x direction of the spin orbit torque wiring 2, the magnetization reversal of the first ferromagnetic layer 1A occurs, but the write error rate cannot be said to be sufficiently small. When a voltage higher than the above value is applied in each temperature range, the magnetization of the first ferromagnetic layer 1A can be more stably reversed. That is, more stable data writing can be realized. If a voltage higher than the above value is applied, the write error rate of the magnetic memory 100 can be suppressed to 10 −7 or less.

When the spin orbit torque wiring 2 is tungsten, it is preferable to apply a voltage equal to or higher than the lower limit voltage Vmin below. The lower limit voltage Vmin satisfies V _min = (1.2 × 10 ⁻³ × t + 0.9967) × Vo in a temperature region where the environmental temperature is less than 20 ° C., and in a temperature region where the environmental temperature is 20 ° C. or more, It is preferable to satisfy V _min = (9.3 × 10 ⁻³ × t + 0.835) × Vo.

When the spin orbit torque wiring 2 is tantalum, it is preferable to apply a voltage equal to or higher than the lower limit voltage Vmin below. The lower limit voltage Vmin satisfies V _min = (0.5 × 10 ⁻³ × t + 1.01) × Vo in the temperature region where the environmental temperature is less than 20 ° C., and in the temperature region where the environmental temperature is 20 ° C. or more, It is preferable to satisfy V _min = (0.8 × 10 ⁻³ × t + 1.005) × Vo.

In addition, when the spin orbit torque wiring 2 is iridium, it is preferable to apply a voltage equal to or higher than the following lower limit voltage Vmin. The lower limit voltage Vmin satisfies V _min = (0.2 × 10 ⁻³ × t + 1.0567) × Vo in the temperature region where the environmental temperature is less than 20 ° C., and in the temperature region where the environmental temperature is 20 ° C. or more, It is preferable to satisfy V _min = (1.1 × 10 ⁻³ × t + 1.0375) × Vo.

Further, when the spin orbit torque wiring 2 is platinum, it is preferable to apply a voltage equal to or higher than the following lower limit voltage Vmin. The lower limit voltage Vmin satisfies V _min = (0.3 × 10 ⁻³ × t + 1.0033) × Vo in the temperature region where the environmental temperature is less than 20 ° C., and in the temperature region where the environmental temperature is 20 ° C. or more, It is preferable to satisfy V _min = (0.2 × 10 ⁻³ × t + 1.005) × Vo.

In the above relational expression, V ₀ is a critical write voltage at 20 ° C., and t is an environmental temperature (° C.).

  The voltage applied in the x direction of the spin orbit torque wiring 2 is preferably 1.2 times or more and 1.54 times or less the critical write voltage. The environmental temperature to which the magnetic memory 100 is exposed varies depending on the use state of the user. Therefore, there is a case where guarantee of data in a wide temperature range of −40 ° C. or more and 100 ° C. or less is required. If a voltage not less than 1.2 times and not more than 1.54 times the critical write voltage is applied in the x direction of the spin orbit torque wiring 2, data can be stably written in a wide temperature range from -40 ° C to 100 ° C. it can.

<Thermometer>
FIG. 3 is a schematic cross-sectional view of another example of the magnetic memory according to the present embodiment. As shown in FIG. 3, the magnetic memory 101 may include a thermometer 30. The thermometer 30 converts the temperature of the spin orbit torque wiring 2 from the resistance value of the spin orbit torque wiring 2. The converted temperature is sent to the voltage control unit 40. The voltage control unit 40 determines the voltage that the voltage source 20 applies to the spin orbit torque wiring 2 based on the temperature.

  If the temperature at the time of use is measured by the thermometer 30, it is not necessary to limit the range of the write voltage to a controllable range over the entire environmental temperature range where the magnetic memory is used. The write voltage can be determined in accordance with the environmental temperature actually used, and more optimal data writing can be performed.

  The thermometer 30 is not limited to one, and there may be a plurality of thermometers. For example, the thermometer 30 may be installed at each of four corner positions when the spin orbit torque wiring 2 is viewed from the z direction.

  1 and 3 exemplify the case where the spin memory torque type magnetoresistive effect element 10 including the functional unit 1 and the spin orbit torque wiring 2 is one in the magnetic memories 100 and 101. There may be a plurality of effect elements 10. In order to improve the integration of the magnetic memories 100 and 101, it is preferable that the distance between adjacent spin orbit torque type magnetoresistive elements 10 be as close as possible. Therefore, the heat generation of the adjacent spin orbit torque type magnetoresistive effect element 10 may affect the write voltage value. In this case, more accurate data writing can be performed by accurately measuring the temperature of each spin orbit torque wiring 2 with a plurality of thermometers 30.

As described above, according to the magnetic memory according to the present embodiment, data can be stably written.

(Data writing method)
The data writing method according to the present embodiment controls the write voltage applied in the x direction of the spin orbit torque wiring 2 of the spin orbit torque type magnetoresistive effect element 10 described above.

  The write voltage is not less than the critical write voltage at the environmental temperature and not more than a predetermined value. The predetermined value is obtained in the same manner as described above.

  In the temperature region where the environmental temperature is 20 ° C. or higher, the writing voltage is preferably not less than 1.65 times the critical writing voltage at the environmental temperature and not lower than 20 ° C., and the environmental temperature is less than 20 ° C. In the case of the region, the critical writing voltage is preferably not less than the critical writing voltage at ambient temperature and not more than 1.54 times the critical writing voltage at 20C.

  The write voltage is preferably 1.01 or more times the critical write voltage in the temperature region of 20 ° C. or more, more preferably 1.08 or more times the critical write voltage, and 1.15 times or more the critical write voltage. More preferably. In the temperature region below 20 ° C., the write voltage is preferably 1.05 times or more the critical write voltage. Furthermore, the write voltage is more preferably 1.2 times or more and 1.54 times or less the critical write voltage in a temperature range of −40 ° C. or more and 100 ° C. or less.

  When the material of the spin orbit torque wiring 2 is specified, it is preferable to determine the upper limit value and the lower limit value applied at the time of data writing based on the above relational expression.

  The critical write voltage at the environmental temperature may be measured at each temperature, or an approximate value of the critical write voltage in another temperature region may be calculated from the critical write voltages at −40 ° C., 20 ° C., and 100 ° C.

  As described above, according to the data writing method of the present embodiment, data can be stably written in the magnetic memory.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Can be modified or changed.

Example 1
A spin orbit torque type magnetoresistive element 10 shown in FIG. 1 was produced. 3 nm of tungsten (W) was laminated on the thermally oxidized Si substrate. Then, the layer made of tungsten was processed to have a width of 50 nm and a length of 300 nm to form a spin orbit torque wiring 2. The periphery was covered with an insulating film made of silicon oxide.

Next, on the spin orbit torque wiring 2 and the insulating film, CoFeB (thickness 1 nm), MgAl ₂ O ₄ (thickness 3 nm), CoFeB (thickness 1 nm), Ta (thickness 0.4 nm), [Co (thickness 0.4 nm) / Pt (thickness 0.8 nm)] ₄ , Co (thickness 0.4 nm), Ru (thickness 0.4 nm), [Co (thickness 0.4 nm) / Pt (thickness 0.8 nm)] ₅ , Co (thickness 0) .4 nm) and Pt (thickness 10 nm) in this order. And after annealing the produced layer at 350 degreeC, it processed into the square of 50 nm x 50 nm, and the function part 1 was produced. CoFeB deposited first corresponds to the first ferromagnetic layer 1A, MgAl ₂ O ₄ corresponds to the nonmagnetic layer 1C, and a SAF (synthetic antiferromagnetic) structure corresponds to the second ferromagnetic layer 1B. The first ferromagnetic layer 1A is a perpendicular magnetization film.

  The spin orbit torque type magnetoresistive effect elements 10 were arranged in an array of 10 × 10, and each spin orbit torque wiring 2 was connected to the voltage source 20 to complete the magnetic memory. Then, a write pulse was applied to the spin orbit torque wiring 2 to evaluate a change in the write error rate. At the time of writing, a magnetic field of 100 Oe was applied in the x direction. The write pulse has a pulse width of 10 nsec. A cycle time of 60 nsec of 10 nsec for writing, 10 nsec for standby, 20 nsec for reading, and 10 nsec for standby was defined as one cycle time. For the write error rate, the resistance value of each element is measured in the low resistance state and the high resistance state, and the average resistance of each element is used as a reference for writing data of “0” and “1”, and the target write state cannot be realized. Counted in error. At the time of reading data, a voltage of 1 mV was applied in the stacking direction of the functional unit 1.

FIG. 4A shows a change in the write error rate of the magnetic memory of Example 1 when the applied voltage value of the write pulse is changed. In a state where the applied voltage is low, writing has not started, so the intended writing state is not realized and an error is output. On the other hand, when the applied voltage value is increased, writing starts and the writing error rate is reduced. The critical write voltage V ₀ was 0.04842V, and the write error rate was 10 ⁻⁷ when 0.04890V was applied. The voltage at which the write error rate is 10 ⁻⁷ or less is defined as the lower limit voltage V ₁ . The lower limit voltage V ₁ was 1.01 times the critical write voltage V ₀ .

FIG. 4B shows a change in the write error rate of the magnetic memory of Example 1 when the applied voltage value of the write pulse is changed. When the applied voltage exceeds a predetermined value, the write error rate increases. When a write error rate is the voltage was ^{10 -7} or more and the upper limit voltage _{V 2,} the upper limit voltage _{V 2} was 0.08038V. This upper limit voltage V ₂ was 1.66 times the critical write voltage V ₀ .

The graph shown in FIG. 4A can be fitted by the following relational expression (1). In the following relational expression, P ₁ is an anti-equilibrium state (data “1”) to an equilibrium state (data “0”) or an equilibrium state (data “0”) to an anti-equilibrium state (data “1”). _Tp is the applied pulse time, t ₀ is the time required for the theoretical magnetization reversal, Δ _{P (AP)} is a value indicating thermal stability, and V ₀ is the critical Write voltage. ΔP _(AP) is determined by KV / kBT (K is uniaxial magnetic anisotropy, V is volume, kB is Boltzmann constant, and T is absolute temperature).

Further, the graph shown in FIG. 4B can be fitted by the following relational expression (2). In the following relational expression, P2 is in an anti-equilibrium state (data “1”) or an equilibrium state (data “0”) and is in an unstable state (data “0. 5 ") on the probability of transition, t _p is the applied pulse time, t ₀ is the time required to theoretically magnetization reversal, it is generally 1 nsec. ΔP _(AP) is a value indicating thermal stability, and V ₀ ′ is a limit writing voltage. ΔP _(AP) is obtained by KV / k _B T (K is uniaxial magnetic anisotropy, V is volume, k _B is Boltzmann constant, and T is absolute temperature). The limit write voltage V ₀ ′ is a voltage when the write error rate reaches 10 ⁻³ from the state where data can be stably written.

(Example 2)
The second embodiment is different from the first embodiment in that the environmental temperature to which the magnetic memory is exposed is set to −40 ° C. Other conditions were the same as in Example 1. The resistivity of the spin orbit torque wiring 2 was 53.8 μΩcm at 20 ° C., but became 40 μΩcm.

The critical write voltage V ₀ at −40 ° C. of the magnetic memory in Example 2 was 0.04554V, the lower limit voltage V ₁ was 0.04600V, and the upper limit voltage V ₂ was 0.07457V. That is, the lower limit voltage V ₁ was 0.95 times the critical write voltage V ₀ at 20 ° C., and the upper limit voltage V ₂ was 1.54 times the critical write voltage V ₀ at 20 ° C.

(Example 3)
The third embodiment is different from the first embodiment in that the environmental temperature to which the magnetic memory is exposed is set to 100 ° C. Other conditions were the same as in Example 1. The resistivity of the spin orbit torque wiring 2 was 53.8 μΩcm at 20 ° C., but became 73 μΩcm.

The critical write voltage V ₀ at 100 ° C. of the magnetic memory in Example 3 was 0.05178V, the lower limit voltage V ₁ was 0.05229V, and the upper limit voltage V ₂ was 0.08522V. That is, the lower limit voltage V ₁ was 1.08 times the critical write voltage V ₀ at 20 ° C., and the upper limit voltage V ₂ was 1.76 times the critical write voltage V ₀ at 20 ° C.

Example 4
The fourth embodiment is different from the first embodiment in that the environmental temperature to which the magnetic memory is exposed is set to 0 ° C. Other conditions were the same as in Example 1. The critical writing voltage V _{0 at} 0 ° C. was estimated to be 0.04746 V from the results of −40 ° C. and 20 ° C.

Lower limit voltage _{V 1} of the magnetic memory in Embodiment 4 is 0.04794V, the upper limit voltage _{V 2} was 0.07844V. That is, the lower limit voltage V ₁ was 0.99 times the critical write voltage V ₀ at 20 ° C., and the upper limit voltage V ₂ was 1.62 times the critical write voltage V ₀ at 20 ° C. This value satisfies the relational expression when the spin orbit torque wiring 2 is tungsten. Also an estimated been critical write voltage, that upper limit voltage V ₂ is within the predetermined range, it was confirmed that data can be written stably.

(Example 5)
The fifth embodiment is different from the first embodiment in that the environmental temperature to which the magnetic memory is exposed is 50 ° C. Other conditions were the same as in Example 1. The critical writing voltage V _{0 at} 50 ° C. was estimated from the results at 20 ° C. and the results at 100 ° C., and was 0.04968V.

Lower limit voltage _{V 1} of the magnetic memory according to the fifth embodiment is 0.05018V, the upper limit voltage _{V 2} was 0.08219V. That is, the lower limit voltage V1 was 1.04 times the critical write voltage V ₀ at 20 ° C., and the upper limit voltage V ₂ was 1.70 times the critical write voltage V ₀ at 20 ° C. This value satisfies the relational expression when the spin orbit torque wiring 2 is tungsten. Also an estimated been critical write voltage, that upper limit voltage V ₂ is within the predetermined range, it was confirmed that data can be written stably.

(Example 6)
Example 6 is different from Example 1 in that the material constituting the spin orbit torque wiring 2 is changed from tungsten (W) to tantalum (Ta). Other conditions were the same as in Example 1.

5A and 5B show changes in the write error rate of the magnetic memory of Example 6 when the applied voltage value of the write pulse is changed. The graph shown in FIG. 5A could be fitted with the above relational expression (1), and the graph shown in FIG. 5B could be fitted with the above relational expression (2). The critical writing voltage V ₀ was 0.1423V, and the lower limit voltage V ₁ was 0.1438V. The lower limit voltage V ₁ was 1.01 times the critical write voltage V ₀ . Upper limit voltage _{V 2} was 0.2349V. Upper limit voltage _{V 2} was 1.65 times the critical write voltage _{V 0.}

(Example 7)
The seventh embodiment is different from the sixth embodiment in that the environmental temperature to which the magnetic memory is exposed is set to -40 ° C. Other conditions were the same as in Example 6. The resistivity of the spin orbit torque wiring 2 was 131.8 μΩcm at 20 ° C., but was 102 μΩcm.

The critical write voltage V ₀ at −40 ° C. of the magnetic memory in Example 7 was 0.1395 V, the lower limit voltage V ₁ was 0.1409 V, and the upper limit voltage V ₂ was 0.2278 V. That is, the lower limit voltage V ₁ was 0.99 times the critical write voltage V ₀ at 20 ° C., and the upper limit voltage V ₂ was 1.60 times the critical write voltage V ₀ at 20 ° C.

(Example 8)
The eighth embodiment is different from the sixth embodiment in that the environmental temperature to which the magnetic memory is exposed is set to 100 ° C. Other conditions were the same as in Example 6. The resistivity of the spin orbit torque wiring 2 was 131.8 μΩcm at 20 ° C., but was 167 μΩcm.

The critical write voltage V ₀ at 100 ° C. of the magnetic memory in Example 8 was 0.1423 V, the lower limit voltage V ₁ was 0.1438 V, and the upper limit voltage V ₂ was 0.2349 V. That is, the lower limit voltage V ₁ was 1.01 times the critical write voltage V ₀ at 20 ° C., and the upper limit voltage V ₂ was 1.65 times the critical write voltage V ₀ at 20 ° C.

Example 9
Example 9 is different from Example 1 in that the material constituting the spin orbit torque wiring 2 is changed from tungsten (W) to iridium (Ir). Other conditions were the same as in Example 1.

6A and 6B show changes in the write error rate of the magnetic memory of Example 9 when the applied voltage value of the write pulse is changed. The graph shown in FIG. 6A could be fitted with the above relational expression (1), and the graph shown in FIG. 6B could be fitted with the above relational expression (2). The critical writing voltage V ₀ was 0.04036V, and the lower limit voltage V ₁ was 0.04076V. The lower limit voltage V ₁ was 1.06 times the critical write voltage V ₀ . Upper limit voltage _{V 2} was 0.06982V. Upper limit voltage _{V 2} was 1.72 times the critical write voltage _{V 0.}

(Example 10)
The tenth embodiment differs from the ninth embodiment in that the environmental temperature to which the magnetic memory is exposed is set to -40 ° C. Other conditions were the same as in Example 9. The resistivity of the spin orbit torque wiring 2 was 47.2 μΩcm at 20 ° C. to 39 μΩcm.

The critical write voltage V ₀ at −40 ° C. of the magnetic memory in Example 10 was 0.04036 V, the lower limit voltage V ₁ was 0.04237 V, and the upper limit voltage V ₂ was 0.06901 V. That is, the lower limit voltage V ₁ was 1.05 times the critical write voltage V ₀ at 20 ° C., and the upper limit voltage V ₂ was 1.71 times the critical write voltage V ₀ at 20 ° C.

(Example 11)
Example 11 differs from Example 9 in that the ambient temperature to which the magnetic memory is exposed is set to 100 ° C. Other conditions were the same as in Example 9. The resistivity of the spin orbit torque wiring 2 was 47.2 μΩcm at 20 ° C., but became 68 μΩcm.

The critical write voltage V ₀ at 100 ° C. of the magnetic memory in Example 11 was 0.04595V, the lower limit voltage V ₁ was 0.04641V, and the upper limit voltage V ₂ was 0.075547V. That is, the lower limit voltage V ₁ was 1.15 times the critical write voltage V ₀ at 20 ° C., and the upper limit voltage V ₂ was 1.87 times the critical write voltage V ₀ at 20 ° C.

(Example 12)
Example 12 differs from Example 1 in that the material constituting the spin orbit torque wiring 2 is changed from tungsten (W) to platinum (Pt). Other conditions were the same as in Example 1.

7A and 7B show changes in the write error rate of the magnetic memory of Example 12 when the applied voltage value of the write pulse is changed. The graph shown in FIG. 7A could be fitted with the above relational expression (1), and the graph shown in FIG. 7B could be fitted with the above relational expression (2). The critical writing voltage V ₀ was 0.1046V, and the lower limit voltage V ₁ was 0.1057V. The lower limit voltage V ₁ was 1.01 times the critical write voltage V ₀ . Upper limit voltage _{V 2} was 0.1726V. Upper limit voltage _{V 2} was 1.65 times the critical write voltage V0.

(Example 13)
Example 13 differs from Example 12 in that the ambient temperature to which the magnetic memory is exposed is set to -40 ° C. Other conditions were the same as in Example 13. The resistivity of the spin orbit torque wiring 2 was 105.7 μΩcm at 20 ° C. and now 82 μΩcm.

The critical write voltage V ₀ at −40 ° C. of the magnetic memory in Example 13 was 0.1025 V, the lower limit voltage V ₁ was 0.1036 V, and the upper limit voltage V ₂ was 0.1674 V. That is, the lower limit voltage V ₁ was 1.0 times the critical write voltage V ₀ at 20 ° C., and the upper limit voltage V ₂ was 1.60 times the critical write voltage V ₀ at 20 ° C.

(Example 14)
Example 14 differs from Example 12 in that the environmental temperature to which the magnetic memory is exposed is 100 ° C. Other conditions were the same as in Example 12. The resistivity of the spin orbit torque wiring 2 was 105.7 μΩcm, which was 105.7 μΩcm at 20 ° C.

The critical write voltage V0 at 100 ° C. of the magnetic memory in Embodiment 14 is 0.1067V, the lower limit voltages _{V 1} is 0.1078V, the upper limit voltage _{V 2} was 0.1747V. That is, the lower limit voltage V ₁ was 1.03 times the critical write voltage V ₀ at 20 ° C., and the upper limit voltage V ₂ was 1.67 times the critical write voltage V ₀ at 20 ° C.

  In addition, it was able to fit using the relational expression (1) and the relational expression (2) also in the result of changing the temperature in each material.

DESCRIPTION OF SYMBOLS 1 Functional part 1A 1st ferromagnetic layer 1B 2nd ferromagnetic layer 1C Nonmagnetic layer 2 Spin orbit torque wiring 3 1st electrode 4 2nd electrode 10 Spin orbit torque type magnetoresistive effect element 20 Voltage source 30 Thermometer 40 Voltage control Part 100, 101 magnetic memory

Claims (4)

A spin orbit torque wiring extending in a first direction; and laminated on one surface of the spin orbit torque wiring, comprising a first ferromagnetic layer, a nonmagnetic layer, and a second ferromagnetic layer from the spin orbit torque wiring side. In a spin orbit torque type magnetoresistive effect element comprising a functional part,
The voltage applied in the first direction of the spin orbit torque wiring is a critical writing voltage at ambient temperature and a predetermined value or less,
The predetermined value is
When the ambient temperature is −40 ° C., 20 ° C., and 100 ° C., the limit writing in which the write error rate when the magnetization of the first ferromagnetic layer is reversed becomes equal to the write error rate when the critical write voltage is applied. A method of writing data, which is a voltage. A spin orbit torque wiring extending in a first direction; and laminated on one surface of the spin orbit torque wiring, comprising a first ferromagnetic layer, a nonmagnetic layer, and a second ferromagnetic layer from the spin orbit torque wiring side. In a spin orbit torque type magnetoresistive effect element comprising a functional part,
The voltage applied in the first direction of the spin orbit torque wiring is a critical writing voltage at ambient temperature and a predetermined value or less,
The predetermined value is
When the ambient temperature is −40 ° C., 20 ° C., and 100 ° C., the limit writing in which the write error rate when the magnetization of the first ferromagnetic layer is reversed becomes equal to the write error rate when the critical write voltage is applied. Voltage
A data writing method, which is a voltage located on a straight line connecting a limit writing voltage at −40 ° C. and a limit writing voltage at 20 ° C. in a temperature region where the environmental temperature is less than 20 ° C. A spin orbit torque wiring extending in a first direction; and laminated on one surface of the spin orbit torque wiring, comprising a first ferromagnetic layer, a nonmagnetic layer, and a second ferromagnetic layer from the spin orbit torque wiring side. In a spin orbit torque type magnetoresistive effect element comprising a functional part,
The voltage applied in the first direction of the spin orbit torque wiring is a critical writing voltage at ambient temperature and a predetermined value or less,
The predetermined value is
When the ambient temperature is −40 ° C., 20 ° C., and 100 ° C., the limit writing in which the write error rate when the magnetization of the first ferromagnetic layer is reversed becomes equal to the write error rate when the critical write voltage is applied. Voltage
A data writing method, which is a voltage located on a straight line connecting a limit writing voltage at 20 ° C. and a limit writing voltage at 100 ° C. in a temperature region where the environmental temperature is 20 ° C. or higher. A spin orbit torque wiring extending in a first direction; and laminated on one surface of the spin orbit torque wiring, comprising a first ferromagnetic layer, a nonmagnetic layer, and a second ferromagnetic layer from the spin orbit torque wiring side. In a spin orbit torque type magnetoresistive effect element comprising a functional part,
The voltage applied in the first direction of the spin orbit torque wiring is a critical writing voltage at ambient temperature and a predetermined value or less,
The predetermined value is V ₀ ′ when P ₂ = 10 ^{−3 in} the following relational expression (2);

In the relational expression (2),
P ₂ changes from an anti-equilibrium state (data “1”) or an equilibrium state (data “0”) to an equilibrium state or an anti-equilibrium state, or an unstable state (data “0.5”). Is the probability of transition,
t _p is the applied pulse time,
t ₀ is theoretically the time required for magnetization reversal,
ΔP _(AP) = KV / k _B T (K is uniaxial magnetic anisotropy, V is volume, k _B is Boltzmann constant, and T is absolute temperature).

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