WO2018021706A1

WO2018021706A1 - Magnetic nano-oscillation element

Info

Publication number: WO2018021706A1
Application number: PCT/KR2017/006879
Authority: WO
Inventors: 이경진; 이서원; 장평화
Original assignee: 고려대학교 산학협력단
Priority date: 2016-07-27
Filing date: 2017-06-29
Publication date: 2018-02-01
Also published as: KR101763073B1

Abstract

A nano-oscillation element according to one embodiment of the present invention comprises: a first fixed magnetic layer; a second fixed magnetic layer arranged on the first fixed magnetic layer; a free magnetic layer interposed between the first fixed magnetic layer and the second fixed magnetic layer; a first non-magnetic layer interposed between the first fixed magnetic layer and the free magnetic layer; and a second non-magnetic layer interposed between the free magnetic layer and the second fixed magnetic layer. The first fixed magnetic layer has a fixed magnetization direction and is a thin film made of a material to be magnetized in the direction perpendicular to a film surface thereof. The free magnetic layer has a cone state aligned in the direction for maintaining a specific angle with respect to the direction perpendicular to a surface thereof. The second fixed magnetic layer has a fixed magnetization direction and is made of a material to be magnetized in the direction parallel to the film surface thereof.

Description

Magnetic Nano Oscillation Device

The present invention relates to a nano oscillation device using a magnetic tunnel junction (MTJ) or a giant magnetoresistive effect, and more particularly, precession of magnetization of a free magnetic layer by applying a current to a free magnetic layer having a cone magnetization state. It relates to a nano oscillation device that generates microwaves by inducing.

1 is a cross-sectional view illustrating a structure of a nano oscillation device using a conventional spin transfer torque and an external magnetic field.

Referring to FIG. 1, the magnetic tunnel junction structure 100 includes a lower electrode 110, a fixed magnetic layer 120, an insulating layer 130, a free magnetic layer 140, and an upper electrode 150. The pinned magnetic layer 120 has an in-plane fixed magnetization direction, and the free magnetic layer has a magnetization direction switched in-plane. In the magnetic tunnel junction structure 100, a tunnel magnetoresistance effect in which electrical resistance varies depending on a relative magnetization direction between the pinned magnetic layer 120 and the free magnetic layer 140 is generated. The tunnel magnetoresistance effect occurs because electrons of up-spin and down-spin tunnel through the insulating layer 130 in the magnetic tunnel junction structure. This tunnel magnetic resistance effect is larger than the giant magnetoresistance generated in the spin valve structure (first magnetic material / nonmagnetic material / second magnetic material) in which a nonmagnetic material is inserted between two ferromagnetic materials. Therefore, in the case of a nano oscillation device, the magnetic tunnel junction structure has an advantage of generating microwaves with higher power.

Due to the tunnel magnetoresistance effect, the relative magnetization directions of the two magnetic layers control the flow of current. On the other hand, according to Newton's third law of action-reaction, if the relative magnetization direction can control the flow of current, it is also possible to apply the current in the reaction to affect the magnetization direction of the magnetic layer. When a current is applied to the magnetic tunnel junction structure in a vertical (thickness) direction, the current spin-polarized by the fixed magnetic layer 120 passes through the free magnetic layer 140 to transmit its spin angular momentum. do. The torque felt by magnetization by the transfer of spin angular momentum is called spin-transfer-torque. Using spin transfer torque, the magnetization of the free magnetic layer can be switched. When the external magnetic field (Bext) is caught together, magnetization precession motion is possible to continuously rotate the magnetization.

Conventional nano-oscillation device applying a magnetic tunnel junction structure composed of a magnetic material having magnetization in the in-plane direction is a free magnetic layer in which the direction of magnetization is changed by the lower electrode 110 / fixed magnetic layer 120 / insulating layer 130 / current Has a structure of 140 / upper electrode 150. Transistors (not shown) are disposed above or below the magnetic tunnel junction structure. The transistor serves to provide a current flowing in a vertical direction to the magnetic tunnel junction located above or below.

When a current from the transistor is applied in a direction perpendicular to the membrane surface and an external magnetic field Bext having an appropriate direction and value is applied, a magnetization precession motion in which magnetization is continuously rotated is induced in the free magnetic layer 140. In this case, as the magnetization of the free magnetic layer 140 rotates with respect to the fixed magnetic layer 120 having a constant magnetization direction in plane, the relative direction between the two magnetizations is continuously changed. Therefore, the resistance varies depending on the tunnel magnetoresistance. This causes microwaves.

2 is a cross-sectional view illustrating a structure of a nano oscillation device using a conventional spin hole spin torque and an external magnetic field.

Referring to FIG. 2, a device for inducing magnetized precession by walking a spin hole spin torque generated by an in-plane current flowing through a conductive wire and an external magnetic field has been developed. The nano oscillation device 200 includes a lower electrode 210, a fixed magnetic layer 220, an insulating layer 230, a free magnetic layer 240, and a conductive line 250. The magnetization precession of the free magnetic layer 240 is induced by an external magnetic field (Bext) applied from the outside and a current flowing in the in-plane direction to the conductive wire 250. Here, the magnetization direction of the pinned magnetic layer 220 or free magnetic layer 240 is aligned in the x direction or the -x direction in the placement plane of the thin film. Spin-hole effect in which the up-spin and down-spin electrons flowing in the conductive wire 250 are polarized in different directions by spin-orbit interaction Experience the Spin Hall Effect. Accordingly, the generation of spin current in all directions perpendicular to the current direction has already been experimentally verified. At this time, the spin current generated in each direction has a spin component biased perpendicular to the direction (direction of spin current).

Referring to the coordinate system shown in FIG. 2, when the in-plane current in the conductive line 250 flows in the -y direction or the + y direction, the -z direction component (that is, the spin current incident on the free magnetic layer) among the generated spin currents is -x. It has a spin component in the direction or + x direction and flows into a free magnetic body. The free magnetic material 240 is subjected to spin torque by the spin current flowing into the free magnetic material 240. In this case, the spin torque is called spin hole spin torque. The magnetization of the free magnetic material 240 subjected to the spin hole spin torque performs magnetization precession around the + z axis or the -z axis according to the external magnetic field (Bext) and the magnitude and direction of the applied current.

The magnetization precession motion according to an embodiment of the present invention is an experimental and theoretical study in which the magnetization of the magnetic layer is reversed using spin hole spin torque [I. M. Miron et al., Nature 476, 189 (2011), L. Liu et al., Science 336, 555 (2012). When the spin hole spin torque serves to reverse the magnetization of the magnetic layer, if the external magnetic field is applied together in the opposite direction, the magnetization is precessed.

However, the nano oscillation device using both spin transfer torque and external magnetic field has a limitation in practical use because it requires a device that additionally supplies an external magnetic field compared to the existing oscillation device. In order to overcome this, a nano oscillation device that oscillates without an external magnetic field is required.

One technical problem to be solved of the present invention is to use the magnetic anisotropy of the material without an external magnetic field to transfer the surface vertical current spin transfer torque to the free magnetic layer having a cone state to induce magnetization precession of the free magnetic layer.

In the nano oscillation device according to an embodiment of the present invention, as in the conventional structure, the magnetization precession of the free magnetic layer due to spin transfer torque or spin hole spin torque due to the current flowing in the vertical direction or in-plane direction of the conductor in the magnetic tunnel junction structure and the external magnetic field Do not induce exercise.

Nano oscillation device according to an embodiment of the present invention, the first pinned magnetic layer; A second pinned magnetic layer disposed on the first pinned magnetic layer; A free magnetic layer interposed between the first pinned magnetic layer and the second pinned magnetic layer; A first nonmagnetic layer interposed between the first pinned magnetic layer and the free magnetic layer; And a second nonmagnetic layer interposed between the free magnetic layer and the second pinned magnetic layer. The first pinned magnetic layer is a thin film made of a material having a fixed magnetization direction and magnetized in a direction perpendicular to the membrane surface. The free magnetic layer has a cone state that is aligned in a direction maintaining a specific angle from the plane vertical direction. The second pinned magnetic layer has a fixed magnetization direction and is made of a material that is magnetized in a direction parallel to the membrane surface.

In one embodiment of the invention,

The free magnetic layer is

(

),

K ₁ , K ₂ , K _{1, eff} , and M _s are the effective magnetic anisotropy, including the first term, second term, first term and demagnetization energy density of the magnetic anisotropy energy density, respectively. anisotropy energy density, and saturation magnetization value.

In one embodiment of the present invention, the first pinned magnetic layer may be a semi-magnetic structure consisting of a magnetic layer, a nonmagnetic layer, and a second auxiliary magnetic layer stacked in sequence. The second pinned magnetic layer may have a semimagnetic structure composed of a magnetic layer, a nonmagnetic layer, and a magnetic layer, which are sequentially stacked. The magnetic layer may be made of a material including at least one of Fe, Co, Ni, B, Si, Zr, and alloys thereof. The nonmagnetic layer may be made of a material including at least one of Ru, Cu, and alloys thereof.

In one embodiment of the present invention, the first pinned magnetic layer may be an exchange-biased diamagnetic body structure consisting of an antiferromagnetic layer, a magnetic layer, a nonmagnetic layer, and a magnetic layer, which are sequentially stacked. The second pinned magnetic layer may be an exchange biased diamagnetic body structure consisting of a magnetic layer, a nonmagnetic layer, a magnetic layer, and an antiferromagnetic layer, which are sequentially stacked. The antiferromagnetic layer may be made of a material selected from Ir, Pt, Mn, and alloys thereof. Each of the magnetic layer and the magnetic layer may include at least one of Fe, Co, Ni, B, Si, Zr, and alloys thereof. The nonmagnetic layer may include at least one of Ru, Cu, and alloys thereof.

In one embodiment of the present invention, the free magnetic layer may include at least one of Fe, Co, Ni, B, Si, Zr and their alloys.

In one embodiment of the present invention, the first nonmagnetic layer and the second nonmagnetic layer is an insulating layer, the insulating layer may include at least one of AlOx, MgO, TaOx, and ZrOx.

In an embodiment of the present invention, the first nonmagnetic layer and the second nonmagnetic layer are metal layers, and the metal layers may include at least one of Cu, Ta, Pt, W, Gd, Bi, Ir, and alloys thereof. Can be.

In one embodiment of the present invention, the first pinned magnetic layer and the second pinned magnetic layer may include at least one of Fe, Co, Ni, B, Si, Zr and alloys thereof.

In one embodiment of the present invention, the free magnetic layer is CoFeB, the thickness of the free magnetic layer may be 0.8nm to 1.2nm.

The magnetic nano oscillation device having a novel structure according to the present invention uses the spin transfer torque and the cone state effective magnetic anisotropy magnetic field of the free magnetic layer to use the principle of inducing precession to the free magnetic layer without applying an external magnetic field. The spin transfer torque is generated in the free magnetic layer by the spin current generated by spin polarization of the current through the fixed magnetic layer.

Nano oscillation device according to an embodiment of the present invention can solve the problem of 1) the need for an additional device to provide an external magnetic field and 2) difficult to adjust the tuning of the frequency.

FIG. 3A is a conceptual diagram illustrating a three-layer structure including a vertical polarizer (p-PL), a nonmagnetic layer, and a conically magnetized free layer (c-FL).

3 (b) is a phase diagram of the demagnetization energy K _{1, eff} and the quadratic anisotropy constant K ₂ .

4 (a) shows spin transfer torque (STT) -induced tilting angle (θ _s ) according to current density.

FIG. 4 (b) shows the theoretical prediction from Macrospin simulation results and Equation 4. FIG.

5 (a) shows the simulation result of the oscillation frequency with respect to the current density.

5 (b) shows a simulation result of power versus current density.

6 shows the ratio K ₂ / | K _{1, eff} | Maximum oscillation frequency and output power are represented as a function of (= -1/2 κ).

7 is a cross-sectional view showing a nano oscillation device according to an embodiment of the present invention.

8 is a cross-sectional view illustrating an oscillation element according to another exemplary embodiment of the present invention.

9 is a cross-sectional view illustrating an oscillation element according to another exemplary embodiment of the present invention.

In the description of an embodiment, each layer (region), region, hole or structure is formed on or "under" or above a substrate, each layer (film), region, pad or hole. In the case of what is described as being to be taken, both above / on and "under" include both "directly" or "indirectly" formed. In addition, the criteria for the top / top or bottom / bottom of each layer will be described based on the drawings.

Like reference numerals in the drawings refer to the same or similar functions throughout the several aspects.

DETAILED DESCRIPTION Hereinafter, specific details for carrying out the present invention will be described with reference to the drawings, and these embodiments will be described in detail enough to enable those skilled in the art to practice the present invention.

It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein may be embodied in other embodiments without departing from the spirit and scope of the invention with respect to one embodiment.

In addition, it is to be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. Accordingly, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled.

Hereinafter, the operating principle of the oscillation element according to an embodiment of the present invention will be described.

According to one embodiment of the present invention, we propose a zero-field microwave oscillator having a perpendicular polarizer and using a conically magnetized free layer. . The conically magnetized free layer was implemented in a sample with a large second order anisotropy constant (K ₂ ).

Referring to FIG. 3A, the vertical polarizer p-PL is a pinned magnetic layer and has a fixed magnetization direction perpendicular to the plane. The nonmagnetic layer may be an insulating layer or a nonmagnetic metal layer. The nonmagnetic metal layer may include at least one of Cu, Ta, Ru, Pt, W, Gd, Bi, Ir, and alloys thereof. The insulating layer may include at least one of AlOx, MgO, TaOx, and ZrOx. The conically magnetized free layer (c-FL) is embodied in a sample having a large second order anisotropy constant (K ₂ ), and is aligned in a direction (cone state) maintaining a specific angle from the plane vertical direction. Has a cone state. The conically magnetized free layer (c-FL) is a CoFeB material, and the thickness thereof may be 0.8 nm to 1.2 nm to maintain a cone state.

Electrons flowing from the vertical polarizer p-PL to the conically magnetized free layer c-FL correspond to the negative current density. The effective magnetic anisotropy energy of the conically magnetized free layer (c-FL) is given by

[Equation 1]

Where θ is the polar angle of magnetization in the spherical coordinate system, and K _{1, eff} (= K ₁ -2πM _s ² ) is a first-order effective anisotropy constant that includes demagnetization energy. K ₁ and K ₂ are the first and second order anisotropy constants. M _s is saturation magnetization.

The magnetic anisotropy easy axis is determined depending on the magnitude and sign of the demagnetization energy (K _{1, eff} ) and the quadratic anisotropy constant (K ₂ ). The demagnetization energy (K _{1, eff} ) and the quadratic anisotropy constant (K ₂ ) are shown in the phase diagram.

For positive demagnetization energy K _{1, eff} , the magnetic layer has a perpendicular magnetic anisotropy (PMA) region. For negative demagnetization energy K _{1, eff} , the magnetic layer has an in-plane magnetic anisotropy (IMA) region or a magnetic easy cone state region. .

The easily magnetized cone state has anisotropic constants of K _{1, eff} <0 and K ₂ > | K _{1, eff} / 2 | If the condition is met, it is stabilized.

From Equation 1, the equilibrium polar angle θ _eq is given by:

[Equation 2]

We explain why spin transfer torque (STT) causes zero-field oscillation for the magnetization cone state.

4 (a) shows the effective anisotropic energy satisfying the conditions for the easy magnetization cone state for K _{1, eff} = -4 x 10 ⁵ erg / cm ³ and K ₂ = 2 x 10 ⁶ erg / cm ³ anisotropy energy; E _{K, eff} ).

Referring to FIG. 4 (a), the effective anisotropic energy E _{K, eff} is an equilibrium angle θ _eq ~ 0.1π) shows the minimum. At θ = θ _eq , the anisotropic magnetic field acting on magnetization disappears. When electrical current is applied to this structure, the spin transfer torque (STT) tilts the magnetization angle from the equilibrium angle (θ _eq ) to the spin transfer torque (STT) -induced tilting angle (θ _s ). This spin transfer torque (STT) -induced tilting makes the effective anisotropic magnetic field non-zero. Thus, the magnetization washes around the non-zero effective magnetic field H _eff .

The spin transfer torque (STT) - induced tilding each (STT-induced tilted angle; θ s) is Landau with Sloane positions ski wherein (Slonczewski term) - by life when tsu equation (Landau-Lifshitz equation) as follows: Can be analyzed.

[Equation 3]

Where α is a damping constant,

Is a unit vector along the free layer magnetization, γ is a gyromagnetic ratio, H _{K, eff} is an effective magnetic anisotropy field, and H _{K, eff} is a derivative of Equation 1 By

Is given by α _J (=

Is the STT magnitude, η is the spin polarization factor, t is the thickness of the free layer, J is the current density,

Is the unit vector of spin polarization.

Here, we ignore the field-like STT for simplicity, even if the field-like STT at the magnetic tunnel junction cannot be ignored.

In the right-hand-side of Equation 3, the first and second terms describe the precession motion and the effective damping motion of magnetization, respectively. From the second term, the effective magnetic field due to the applied current = α _J / α is the spin transfer torque (STT) -induced tilting angle (θ _s ) at the equilibrium angle (θ _eq ) To get out of the way.

For both the vertically magnetized free layer (p-FL) and the conically magnetized free layer (c-FL), switching occurs when the effective magnetic field due to spin torque exceeds a threshold.

However, unlike the vertical magnetized free layer (p-FL) with threshold anisotropy magnetic field value at θ = 0, the conically magnetized free layer (c-FL) is negative with H H _{, 1} and positive at H _{K, eff} . With H _{th, 2} It has two thresholds.

Therefore, in the case of the vertical magnetization free layer p-FL, the magnetization motion does not move until the spin torque exceeds the effective anisotropic magnetic field at θ = 0. On the other hand, in the case of the conically magnetized free layer (c-FL), the magnetization _deviates from θ _eq and the zero-field ultrahigh frequency oscillation is between two thresholds corresponding to the threshold current densities J _{th, 1} and J _{th, 2} . When spin torque is applied, it is realized.

In θ = θ _s , H _{K, eff −} α _J / α = 0. Also, the secondary term vanishes under this condition. Therefore, θ _s is derived from the above condition and can be given as follows.

[Equation 4]

Referring to FIG. 4 (b), the spin transfer torque (STT) -induced tilting angle (θ _s ) is shown as a function of the applied current density between two threshold current densities (J _{th, 1} and J _{th, 2} ). .

In the simulation, we used the following parameters. α = 0.01, M _S = 800 emu / cm ³ , η = 0.5, t = 1 nm, K _{1, eff} = -4 x 10 ⁵ erg / cm ³ , and K ₂ = 2 x 10 ⁶ erg / cm ³ .

The simulation results are in agreement with theoretical predictions. Spin transfer torque (STT) -induced tilting angle θ _s decreases from the equilibrium angle θ _eq at negative current density. On the other hand, the spin transfer torque (STT) -induced tilting angle θ _s increases from the equilibrium angle θ _eq at a positive current density.

The precession frequency is given by the product of a gyromagnetic ratio (γ) and the effective magnetic isotropic magnetic field ( H _{K, eff} ). In this case, the effective magnetic isotropic magnetic field H _{K, eff} due to STT is α _J given by / α. Therefore, the oscillation frequency is given as follows.

[Equation 5]

The oscillation frequency f is linearly proportional to the current density, and the output power P ∝ I ² (ΔR) ² / R is given by

[Equation 6]

5 (b) shows a simulation result of power versus current density.

5 (a) and 5 (b), the oscillation frequency increases almost linearly with respect to the current density regardless of the current polarity. Only when the current density is between the two thresholds, the oscillation frequency is indicated. If the current density exceeds these thresholds, switching occurs instead of oscillation. At a positive threshold current density ((J _{th, 2} = 16 × 10 ⁵ A / cm ² ), the oscillation frequency is at maximum (˜9.5 GHz), while the oscillation angle is at positive current density. As it increases only, the output power increases only with a positive current density.

From equation 3 we have two two-field magnetic fields (H _{th, 1} , H _{th, 2} ) and the corresponding threshold current densities (J _{th, 1} , J _{th, 2} ) are obtained and given by

[Equation 7]

[Equation 8]

[Equation 9]

[Equation 10]

The maximum oscillation frequency and the maximum output power can be derived from equations (5) and (6) at the positive threshold current density of equation (10). The Munter current density, maximum oscillation frequency, and maximum output power depend on the ratio of anisotropy constants (κ). Therefore, in order to obtain a high oscillation frequency, it is necessary to increase the ratio of anisotropy constants (κ).

Referring to Figure 6, K _{1, eff} is fixed at -4 x 10 ⁵ erg / cm ³ . The ratio K ₂ / | K _{1, eff} | As (= -1/2 κ) increases from 2.5 to 20, the maximum oscillation frequency varies about 10 times from -4 GHz to -40 GHz. In addition, the maximum power increases approximately 100 times from ~ 32 to ~ 3500. Ratio K ₂ / K _{1, eff} | The larger (= -1/2 κ) increases the current-induced tuning range of the oscillation frequency.

The increased ratio of the anisotropy constant can be achieved by voltage-induced anisotropy change. The first and second anisotropy constants K ₁ and K ₂ may be modified differently by the voltage-induced strain effect.

In conclusion, we propose an STT-induced zero-field oscillation with an easy magnetization state. We have derived an analytical formula of the oscillation frequency and output power. The maximum oscillation frequency and the power are determined by the ratio of the second to first anisotropy constants (= K ₂ / | K _{1, eff} |).

According to one embodiment of the invention, a zero-magnetic spin torque oscillator with wide frequency tunnability is proposed.

Nano oscillation device according to an embodiment of the present invention includes a vertical polarizer (p-PL) / non-magnetic layer / conically magnetized free layer (c-FL) stacked in sequence. Ultra-high frequency is generated by the precession of the magnetization of the free magnetic layer.

In ferromagnetic materials, magnetic anisotropy causes the magnetization direction to be aligned in the in-plane direction, in the direction perpendicular to the plane, and in the direction of maintaining a specific angle from the plane perpendicular (cone state). There are three states. When the first term (K ₁ ) and the second term (K ₂ ) representing the magnetic anisotropy energy density satisfy Equation (11), the angle of equilibrium (θ _eq as shown in Equation 2 below) Can be obtained. This means that the magnetic anisotropic energy axis maintains a certain angle θ _eq between the direction perpendicular to the plane and the horizontal direction. Referring to Equation 2, the magnetic anisotropic energy axis has a cone state having an angle of (θ _eq ) from the z axis perpendicular to the plane.

[Equation 11]

In Equation 11, K ₁ , K ₂ , K _{1, eff} , and M _s are effective values including the first term, second term, first term and demagnetization energy density of the magnetic anisotropy energy density, respectively. Effective magnetic anisotropy energy density and saturation magnetization value.

Referring to FIG. 7, the nano oscillation device 300 may include a first pinned magnetic layer 320; A second pinned magnetic layer 360 disposed on the first pinned magnetic layer 320; A free magnetic layer 340 interposed between the first pinned magnetic layer 320 and the second pinned magnetic layer 360; A first nonmagnetic layer 330 interposed between the first pinned magnetic layer 320 and the free magnetic layer 340; And a second nonmagnetic layer 350 interposed between the free magnetic layer 340 and the second pinned magnetic layer 360. The first pinned magnetic layer 320 is a thin film made of a material having a fixed magnetization direction and magnetized in a direction perpendicular to the membrane surface. The free magnetic layer 340 has a cone state aligned in a direction maintaining a specific angle from the plane vertical direction. The second pinned magnetic layer 360 is a thin film made of a material having a fixed magnetization direction and magnetized in a direction parallel to the membrane surface.

The lower electrode 310 may be disposed under the first pinned magnetic layer 320 and may be Cu, Ta, Ru, Pt, W, Gd, Bi, Ir, or an alloy thereof. The lower electrode 310 may have a multilayer structure of Ta / Ru.

The first pinned magnetic layer 320 may be disposed on the lower electrode 310. The first pinned magnetic layer 320 may include at least one of Fe, Co, Ni, B, Si, Zr, and alloys thereof. The first pinned magnetic layer 320 may have a multilayer structure of CoFeB / NM (= Ru, Ta) / CoFe or a multi stack structure of Co / Pt. The first pinned magnetic layer may have a perpendicular magnetic anisotropy (PMA). Accordingly, the magnetization direction of the first pinned magnetic layer 320 may be perpendicular to the placement plane.

The first nonmagnetic layer 330 may be vertically aligned on the first pinned magnetic layer 320. The first nonmagnetic layer 330 may be an insulating layer or a nonmagnetic metal layer. When the first nonmagnetic layer 330 is an insulating layer, the first nonmagnetic layer 330 may include at least one of AlOx, MgO, TaOx, and ZrOx. The first nonmagnetic layer 330 may have a MgO, MgAl 2 O 4, or Mg / MgO / Mg structure. When the first nonmagnetic layer is an insulator, the first pinned magnetic layer 320 / the first nonmagnetic layer 330 / the free magnetic layer 340 may form a magnetic tunnel junction.

When the first nonmagnetic layer 330 is a nonmagnetic metal layer, the first pinned magnetic layer 320 / the first nonmagnetic layer 330 / the free magnetic layer 340 may provide a giant magnetoresistive effect. When the first nonmagnetic layer 330 is a nonmagnetic metal layer, the first nonmagnetic layer may be Cu, Ta, Ru, Pt, W, Gd, Bi, Ir, or an alloy thereof.

The free magnetic layer 340 may be vertically aligned on the first nonmagnetic layer 330. The free magnetic layer 340 may include at least one of Fe, Co, Ni, B, Si, Zr, and alloys thereof. The free magnetic layer 340 may be CoFeB. The free magnetic layer 340 may have a cone state aligned in a direction maintaining a specific angle from a plane vertical direction. The free magnetic layer 340 may have a thickness of 0.8 nm to 1.2 nm for the cone state.

The magnetization of the free magnetic layer 340 precesses with respect to the z axis. Therefore, the vertical component of the magnetization of the free magnetic layer 340 is constant. The first pinned magnetic layer 320 and the free magnetic layer 340 having a perpendicular magnetic anisotropy and a magnetization direction perpendicular to a plane have relatively no change in the magnetization direction, thereby providing a tunnel magnetoresistance characteristic or a giant magnetoresistance effect. You may not.

Accordingly, in order to detect the effect of precession of the free magnetic layer by the tunnel magnetoresistance characteristic or the giant magnetoresistance effect, the second nonmagnetic layer 350 and the second nonmagnetic layer 350 and the second magnetoresistive effect which generate a separate magnetoresistance effect The pinned magnetic layer 360 may be disposed. The second pinned magnetic layer 360 has a magnetization direction fixed in plane. That is, the second pinned magnetic layer 360 is made of a material that is magnetized in a direction parallel to the film surface. Accordingly, as the magnetization of the free magnetic layer 340 precesses with respect to the z axis, the horizontal component of the magnetization of the free magnetic layer rotates in plane. Accordingly, the magnetization direction of the second pinned magnetic layer 360 and the horizontal component of the free magnetic layer 340 provide tunnel magnetoresistance characteristics or giant magnetoresistance effects due to changes in the magnetization directions relative to each other over time.

The second nonmagnetic layer 350 may be vertically aligned on the free magnetic layer 340. The second nonmagnetic layer 350 may be an insulating layer or a nonmagnetic metal layer. In the case of the insulating layer, the second nonmagnetic layer may include at least one of AlOx, MgO, TaOx, and ZrOx. The second nonmagnetic layer 350 may have a MgO, MgAl 2 O 4, or Mg / MgO / Mg structure.

When the second nonmagnetic layer 350 is a nonmagnetic metal layer, the second nonmagnetic layer 350 may be Cu, Ta, Ru, Pt, W, Gd, Bi, Ir, or an alloy thereof.

The second pinned magnetic layer 360 may be vertically aligned on the second nonmagnetic layer 350. The second pinned magnetic layer 360 may have a magnetization direction fixed in the thin film surface. For example, the second pinned magnetic layer 360 may be magnetized in the x-axis direction. The second pinned magnetic layer 360 may include at least one of Fe, Co, Ni, B, Si, Zr, and alloys thereof. The second pinned magnetic layer 360 may have a multilayer structure of CoFeB / nonmagnetic metal (= Ru, Ta) / CoFe or a multi stack structure of Co / Pt.

The upper electrode 370 may be disposed on the second pinned magnetic layer 360. The upper electrode 370 may be Cu, Ta, Ru, Pt, W, Gd, Bi, Ir, and alloys thereof. The upper electrode may have a multilayer structure of Ta / Ru.

According to an embodiment of the present invention, the lower electrode 310 / the first pinned magnetic layer 320 / the first nonmagnetic layer 330 / the free magnetic layer 340 / the second nonmagnetic layer 350 / the second pinned magnetic layer ( 360) / upper electrode 370. The magnetization precession of the free magnetic layer 340 is induced by the current flowing in the plane vertical direction. Here, the magnetization direction of the first pinned magnetic layer 320 is aligned in the + z direction. The current from the lower electrode 310 has a spin component biased in a direction parallel or antiparallel to the first pinned magnetic layer 320 according to the magnetization direction of the first pinned magnetic layer 320 and the direction of the current.

When the current from the conductive wire or the lower electrode 310 flows in the + z direction, electrons passing through the first pinned magnetic layer 320 become a spin current deflected in the + z direction, and conversely, the free magnetic layer 340 has a -z direction. The spin current is deflected by. The magnetization of the free magnetic layer 340 is subjected to spin torque by the spin current flowing through the free magnetic layer 340, and is applied to the magnitude of the effective magnetic field corresponding to the intensity of the spin transfer torque and the intensity of the spin transfer torque by the applied current. Therefore, the magnetizing precession is performed at different frequencies around the + z axis.

Referring to FIG. 8, the nano oscillation device 500 may include a first pinned magnetic layer 520; A second pinned magnetic layer 560 disposed on the first pinned magnetic layer 320; A free magnetic layer 340 interposed between the first pinned magnetic layer 520 and the second pinned magnetic layer 560; A first nonmagnetic layer 330 interposed between the first pinned magnetic layer 520 and the free magnetic layer 340; And a second nonmagnetic layer 350 interposed between the free magnetic layer 340 and the second pinned magnetic layer 560. The first pinned magnetic layer 520 has a fixed magnetization direction and is a thin film made of a material that is magnetized in a direction perpendicular to the membrane surface. The free magnetic layer 340 has a cone state aligned in a direction maintaining a specific angle from the plane vertical direction. The second pinned magnetic layer 560 is a thin film made of a material having a fixed magnetization direction and magnetized in a direction parallel to the membrane surface.

The first pinned magnetic layer 520 may include a lower magnetic layer 522 sequentially stacked; Nonmagnetic metal layer 524; And an upper magnetic layer structure formed of the upper magnetic layer 526. The second pinned magnetic layer 560 may include a lower magnetic layer 562 stacked in sequence; Nonmagnetic metal layer 564; And an upper magnetic layer structure formed of the upper magnetic layer 566. The lower

magnetic layers

522 and 562 and the upper

magnetic layers

526 and 566 may be formed of a material including at least one of Fe, Co, Ni, B, Si, Zr, and alloys thereof. The

nonmagnetic metal layers

524 and 564 may be made of a material including at least one of Ru, Cu, and an alloy thereof. The lower magnetic layer 522 and the upper magnetic layer 526 of the first pinned magnetic layer may have perpendicular magnetic anisotropy and have a fixed magnetization direction perpendicular to the plane. Meanwhile, the lower magnetic layer 562 and the upper magnetic layer 566 of the second pinned magnetic layer may have a fixed magnetization direction parallel to the plane.

Referring to FIG. 9, the nano oscillation device 500a may include a first pinned magnetic layer 520a; A second pinned magnetic layer 560a disposed on the first pinned magnetic layer 520a; A free magnetic layer 340 interposed between the first pinned magnetic layer 520a and the second pinned magnetic layer 560a; A first nonmagnetic layer 330 interposed between the first pinned magnetic layer 520a and the free magnetic layer 340; And a second nonmagnetic layer 350 interposed between the free magnetic layer 340 and the second pinned magnetic layer 560a. The first pinned magnetic layer 520a is a thin film made of a material having a fixed magnetization direction and magnetized in a direction perpendicular to the membrane surface. The free magnetic layer 340 has a cone state aligned in a direction maintaining a specific angle from the plane vertical direction. The second pinned magnetic layer 560a has a fixed magnetization direction and is a thin film made of a material that is magnetized in a direction parallel to the membrane surface.

The first pinned magnetic layer 520a may include an antiferromagnetic layer 521 sequentially stacked; Lower magnetic layer 522; Nonmagnetic metal layer 522; And an exchange biased diamagnetic body structure composed of the upper magnetic layer 526. The second pinned magnetic layer 560a may include a lower magnetic layer 562 stacked in this order; Nonmagnetic metal layer 564; It may be an exchange-biased diamagnetic body structure consisting of an upper magnetic layer 566 and an antiferromagnetic layer 567. The

antiferromagnetic layers

521 and 567 may be made of a material selected from Ir, Pt, Mn, and alloys thereof. Each of the lower

magnetic layers

522 and 562 and the upper

magnetic layers

nonmagnetic metal layers

524 and 564 may be formed of a material including at least one of Ru, Cu, and an alloy thereof.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is only provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations are possible from these descriptions.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and all the things that are equivalent to or equivalent to the scope of the claims as well as the claims to be described later belong to the scope of the present invention.

Claims

A first pinned magnetic layer;

A second pinned magnetic layer disposed on the first pinned magnetic layer;

A free magnetic layer interposed between the first pinned magnetic layer and the second pinned magnetic layer;

A first nonmagnetic layer interposed between the first pinned magnetic layer and the free magnetic layer; And

A second nonmagnetic layer interposed between the free magnetic layer and the second pinned magnetic layer,

The first pinned magnetic layer is a thin film made of a material having a fixed magnetization direction and magnetized in a direction perpendicular to the membrane surface,

The free magnetic layer has a cone state that is aligned in a direction maintaining a specific angle from the plane vertical direction when no current flows in the plane vertical direction.

And the second pinned magnetic layer has a fixed magnetization direction and is a thin film made of a material magnetized in a direction parallel to the membrane surface.
The method of claim 1,

The free magnetic layer is

(
),

K 1 , K 2 , K 1, eff , and M s are the effective magnetic anisotropy, including the first term, second term, first term and demagnetization energy density of the magnetic anisotropy energy density, respectively. anisotropy energy density, and saturation magnetization value,

When the driving current flows in the surface vertical direction, the oscillation device is characterized in that the oscillation only when the drive current is between the two threshold currents.
The method of claim 1,

The first pinned magnetic layer is a semi-magnetic structure consisting of a magnetic layer, a nonmagnetic layer, and a second auxiliary magnetic layer stacked in sequence,

The second pinned magnetic layer is a semi-magnetic structure consisting of a magnetic layer, a nonmagnetic layer, and a magnetic layer laminated in sequence,

The magnetic layer is made of a material containing at least one of Fe, Co, Ni, B, Si, Zr and their alloys,

The nonmagnetic layer is a nano oscillation device, characterized in that made of a material containing at least one of Ru, Cu and alloys thereof.
The method of claim 1,

The first pinned magnetic layer is an exchange-biased diamagnetic body structure consisting of an antiferromagnetic layer, a magnetic layer, a nonmagnetic layer, and a magnetic layer, which are sequentially stacked,

The second pinned magnetic layer is an exchange-biased diamagnetic body structure consisting of a magnetic layer, a nonmagnetic layer, a magnetic layer, and an antiferromagnetic layer, which are sequentially stacked.

The antiferromagnetic layer is made of a material selected from Ir, Pt, Mn, and alloys thereof,

Each of the magnetic layer and the magnetic layer includes at least one of Fe, Co, Ni, B, Si, Zr, and alloys thereof,

The nonmagnetic layer is a nano oscillation device comprising at least one of Ru, Cu and alloys thereof.
The method of claim 1,

The free magnetic layer is a nano oscillation device comprising at least one of Fe, Co, Ni, B, Si, Zr and alloys thereof.
The method of claim 1,

The first nonmagnetic layer and the second nonmagnetic layer are insulating layers,

The insulating layer is a nano oscillation device comprising at least one of AlOx, MgO, TaOx, and ZrOx.
The method of claim 1,

The first nonmagnetic layer and the second nonmagnetic layer are metal layers,

The metal layer is a nano oscillation device comprising at least one of Cu, Ta, Pt, W, Gd, Bi, Ir and alloys thereof.
The method of claim 1,

The first pinned magnetic layer and the second pinned magnetic layer is at least one of Fe, Co, Ni, B, Si, Zr and alloys thereof.
The method of claim 1,

The free magnetic layer is CoFeB,

The thickness of the free magnetic layer is a nano oscillation device, characterized in that 0.8nm to 1.2nm.