A method for reducing switching energy of a magnetic memory cell

Abstract

The application discloses a method for reducing energy consumption of magnetic storage unit flip, relates to the technical field of magnetic storage unit, and aims at reducing energy consumption of information writing. The magnetic storage unit is caused to occur magnetic moment flip through a spin-polarized current. The spin-polarized current gradually changes from an initial value to zero with time. The size of the spin-polarized current is as follows: I t =I0-at; wherein, I t is the spin-polarized current at t nanoseconds since the initial moment, I0 is the initial value of the spin-polarized current at the initial moment, and a is a constant, and a represents a gradual change coefficient. The application has the advantages of stable information writing and low energy consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of magnetic storage unit, more particularly to the technical field of method for reducing the energy consumption of magnetic storage unit. BACKGROUND

[0002] The magnetic storage system refers to a memory made of magnetic material, and the STT-MRAM is a new type of nonvolatile magnetic storage memory for realizing information writing through spin-polarized current. The core of the STT-MRAM storage unit is an MTJ composed of two layers of ferromagnetic layers with different thicknesses and a nanometer-thick non-magnetic isolation layer, and the information writing is realized through spin-polarized current.

[0003] When the current flows through the magnetic layer, the current will be polarized to form a spin-polarized current. The spin electron transmits the spin momentum to the magnetic moment of the free layer, so that the magnetic moment of the spin magnetic layer obtains the spin torque and changes the direction. This process is called spin transfer torque, so the STT-MRAM realizes information writing through spin-polarized current. The core of the STT-MRAM storage unit is still an MTJ composed of two layers of ferromagnetic layers with different thicknesses and a nanometer-thick non-magnetic isolation layer. Through an external circuit, the current can pass through the MTJ from the direction perpendicular to the surface of the MJT. When the current passes through the thicker ferromagnetic layer, the electron is spin-polarized, and the spin direction is the magnetic moment direction of the fixed layer.

[0004] Based on the above working characteristics, the spin-polarized current makes the magnetic storage memory realize information writing and consumes energy. The spin-polarized current injection method used in the storage method is to inject a fixed spin-polarized current in a fixed time, and another method that can successfully write information and reduce energy consumption can effectively realize energy saving. SUMMARY

[0005] The purpose of the present application is to reduce the energy consumption of writing information. In order to solve the above technical problems, the present application provides a method for reducing the energy consumption of magnetic storage unit.

[0006] In order to achieve the above purpose, the present application specifically adopts the following technical scheme:

[0007] A method for reducing the energy consumption of magnetic storage unit, the magnetic storage unit is caused to occur magnetic moment flip through spin-polarized current, the spin-polarized current gradually changes from an initial value to zero with time, and the size of the spin-polarized current is as follows:

[0008] I t = I0-at;

[0009] Wherein, I tis the spin-polarized current at time t nanoseconds from the initial time, I0 is an initial value of the spin-polarized current at the initial time, and a is a constant, and a represents a gradual change coefficient.

[0010] Preferably, the material of the magnetic storage unit is CoFeB.

[0011] Preferably, the cross-sectional diameter of the magnetic storage unit is 80 nm.

[0012] Preferably, the initial value I0 of the spin-polarized current is 4.8 MA / cm2, and the gradual change coefficient a is 0.24. 2

[0013] Preferably, the initial value I0 of the spin-polarized current is 4.9 MA / cm2, and the gradual change coefficient a is 0.2970. 2

[0014] Preferably, the initial value I0 of the spin-polarized current is 5.0 MA / cm2, and the gradual change coefficient a is 0.3333. 2

[0015] The beneficial effects of the present application are as follows:

[0016] Energy saving is achieved by injecting a spin-polarized current that gradually changes from an initial value to zero over time; by selecting appropriate initial values and gradual change coefficients, the magnetic moment flip can be ensured, and information writing can be smoothly and stably achieved; the selected magnetic storage unit is the most widely used magnetic storage unit on the market, so the selected several groups of initial values and gradual change coefficients have high generalizability and can cover most use scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a time-spin-polarized current relationship diagram;

[0018] Figure 2 is a simulated storage magnetic moment flip curve diagram. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0020] ​​​The following detailed description of embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the application as claimed, but merely represents selected embodiments of the application. Based upon the embodiments of the application, all other embodiments that a person of ordinary skill in the art would obtain without inventive effort are within the scope of the application.

[0021] Embodiment 1

[0022] The embodiment provides a method for reducing the energy consumption of magnetic storage unit flip, which makes the magnetic storage unit flip by spin-polarized current, such as Figure 1 The spin-polarized current gradually changes from an initial value to zero over time, and the size of the spin-polarized current is as follows:

[0023] I t = I0- at;

[0024] Wherein, I t is the spin-polarized current at time t nanoseconds since the initial time, I0is the initial value of the spin-polarized current at the initial time, and a is a constant, a representing a gradient coefficient.

[0025] In the embodiment, the material of the magnetic storage unit is CoFeB; and the cross-sectional diameter of the magnetic storage unit is 80 nm.

[0026] As a preferred solution, the initial value I0of the spin-polarized current is 4.8 MA / cm 2 , and the gradient coefficient a is 0.24. The total energy consumption E of the embodiment is:

[0027]

[0028] Wherein t0is the total time length for the spin-polarized current to gradually change from the initial value to zero.

[0029] Similarly, the spin-polarized current injection method commonly used in the conventional storage method is to inject a fixed spin-polarized current I1in a fixed time t1, and the total energy consumption E1= I1 2 t1. In the conventional method, I1for the magnetic storage unit of this specification is 3 MA / cm 2 , and t1is 20 ns.

[0030] By integration, E = 1 / 3 I0 2 t0, so the initial value I0of the embodiment is 4.8 MA / cm 2 , and t0is 20 ns. Calculation shows that the total energy consumption E is 85% of E1, achieving energy saving. And referring to the simulation storage magnetic moment flip curve of Figure 2 The spin-polarized current of the embodiment is sufficient to complete the magnetic moment flip to realize information writing,Figure 2 The ordinate represents the flipping of the magnetic moment, and a value of 1 represents a magnetic moment in the positive direction, and a value of -1 represents a magnetic moment flipped to the negative direction. Flipping of the magnetic moment from the positive direction to the negative direction represents one complete flip.

[0031] Embodiment 2

[0032] The embodiment provides a method for reducing the energy consumption of magnetic memory cell flipping. The magnetic memory cell is flipped by a spin-polarized current, and the spin-polarized current gradually changes from an initial value to zero over time. The size of the spin-polarized current is as follows:

[0033] I t = I0-a t;

[0034] Wherein, I t is the spin-polarized current at t nanoseconds since the initial time, I0 is the initial value of the spin-polarized current at the initial time, and a is a constant, and a represents a gradient coefficient.

[0035] In the embodiment, the material of the magnetic memory cell is CoFeB; and the cross-sectional diameter of the magnetic memory cell is 80 nm.

[0036] As a preferred solution, the initial value I0 of the spin-polarized current is 4.9 MA / cm 2 , and the gradient coefficient a is 0.2970. The total energy consumption E of the embodiment is:

[0037]

[0038] Wherein, t0 is the total time length during which the spin-polarized current gradually changes from the initial value to zero.

[0039] Similarly, the spin-polarized current injection method usually used in the conventional storage method is to inject a fixed spin-polarized current I1 within a fixed time t1, and the total energy consumption E1 = I1 2 t1. In the conventional method, I1 of the magnetic memory of the specification is 3 MA / cm 2 , and t1 is 20 ns.

[0040] By integration, E = 1 / 3 I0 2 t0, so that the initial value I0 of the embodiment is 4.9 MA / cm 2 , t0 is 16.5 ns, and calculation shows that the total energy consumption E is 73% of E1, and energy consumption is saved. And referring to the simulation storage magnetic moment flipping curve of Figure 2 The spin-polarized current of the embodiment is sufficient to complete the magnetic moment flipping and realize information writing, Figure 2The ordinate represents the flipping of the magnetic moment, and a value of 1 represents a magnetic moment in the positive direction, and a value of -1 represents a magnetic moment flipped to the negative direction. A flip of the magnetic moment from the positive direction to the negative direction represents one flip.

[0041] Embodiment 3

[0042] The embodiment provides a method for reducing the energy consumption of a magnetic storage unit. The magnetic moment of the magnetic storage unit is flipped by a spin-polarized current. The spin-polarized current gradually changes from an initial value to zero over time, and the size of the spin-polarized current is as follows:

[0043] I t = I0-a t;

[0044] wherein I t is the spin-polarized current at t nanoseconds since the initial time, I0 is the initial value of the spin-polarized current at the initial time, and a is a constant, and a represents a gradient coefficient.

[0045] In the embodiment, the material of the magnetic storage unit is CoFeB, and the cross-sectional diameter of the magnetic storage unit is 80 nm.

[0046] As a preferred solution, the initial value I0 of the spin-polarized current is 5.0 MA / cm 2 , and the gradient coefficient a is 0.3333. The total energy consumption E of the embodiment is as follows:

[0047]

[0048] wherein t0 is the total time length during which the spin-polarized current gradually changes from the initial value to zero.

[0049] Similarly, the spin-polarized current injection method usually used in a conventional storage method is to inject a fixed spin-polarized current I1 within a fixed time t1, and the total energy consumption E1 of the conventional method is I1 2 t1. In the conventional method, I1 is 3 MA / cm 2 for the magnetic storage unit of the specification, and t1 is 20 ns.

[0050] By integration, E = 1 / 3 I0 2 t0. Therefore, the initial value I0 of the embodiment is 5.0 MA / cm 2 , t0 is 15 ns, and the calculation shows that the total energy consumption E is 69% of E1, and the energy consumption is saved. In addition, referring to the simulation and storage magnetic moment flipping curve of Figure 2 , the spin-polarized current of the embodiment is sufficient to flip the magnetic moment and realize information writing, Figure 2The ordinate of the figure represents the flipping of the magnetic moment, whose value of 1 means that the magnetic moment is in the positive direction, and a value of -1 means that the magnetic moment has flipped to the negative direction, and the flipping of the magnetic moment from the positive square to the negative square represents one complete flip.

Claims

1. A method of reducing switching energy of a magnetic memory cell, comprising: A magnetic storage unit is caused to undergo a magnetic moment flip by a spin-polarized current which varies from an initial value to zero over time, the spin-polarized current having a magnitude as follows: I t = I0- at; where I t is the spin-polarized current at time t nanoseconds from the initial time, I0 is the initial value of the spin-polarized current at the initial time, and a is a constant representing a gradual change coefficient.

2. The method of claim 1, wherein, The material of the magnetic storage unit is CoFeB.

3. The method of reducing switching energy of a magnetic memory cell of claim 2, wherein, The cross-sectional diameter of the magnetic storage unit is 80 nm.

4. The method of reducing switching energy of a magnetic memory cell of claim 3, wherein, The initial value I0 of the spin-polarized current is 4.8 MA / cm 2 The gradient coefficient a is 0.

24.

5. The method of reducing switching energy of a magnetic memory cell of claim 3, wherein, The initial value I0 of the spin-polarized current is 4.9 MA / CM 2 The gradient coefficient a is 0.2970.

6. The method of reducing switching energy of a magnetic memory cell of claim 3, wherein, The initial value I0 of the spin-polarized current is 5.0 MA / cm2 2 The gradient coefficient a is 0.3333.

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