CN110212086B - An in-plane magnetized antiferromagnetic random access memory unit - Google Patents

Abstract

An in-plane magnetized antiferromagnetic random access memory unit, which includes an antiferromagnetic layer, a heavy metal layer, and a first group of terminals connected to the heavy metal layer and a second group of terminals, the first group of terminals is used to connect a pulse current source, The second group of terminals is used to connect the voltage source, and the magnetization state of the antimagnetic layer is in-plane magnetization. The object of the present invention is to provide a memory unit based on in-plane magnetized ferromagnetic material in order to further improve the magnetic moment reversal speed and storage stability of the traditional magnetic memory.

Description

An in-plane magnetized antiferromagnetic random access memory unit

technical field

The invention belongs to the field of electronic memory, in particular to an in-plane magnetized antiferromagnetic RAM storage unit.

Background technique

Magnetic random access memory (MRAM) refers to a random access memory that stores data with a change in magnetoresistance or magnetization state. It uses the difference in magnetization state or the difference in the magnetoresistance value generated by it to record 0 and 1, as long as no external magnetic field or magnetization is applied. When the control current is input, the magnetization state does not change, and the recorded information does not change. Magnetic random access memory has high-speed reading and writing capabilities and high integration, can be erased and written infinitely, and has the advantages of non-volatility, low power consumption, and radiation resistance. It has important applications in computers, industrial automation, aerospace, and defense industries . There are two types of existing magnetic random access memories: one is magnetic field-driven MRAM, and the other is current-driven spin-transfer torque-driven MRAM, referred to as STT-MRAM. There is another type in the current-driven type, that is, due to the spin-orbit coupling of the current in the heavy metal, a spin current perpendicular to the direction of the current is generated, and the torque of the spin current will also act on the adjacent magnetic layer, changing The magnetization state of the magnetic layer is referred to as spin-orbit torque driven MRAM (SOT-MRAM). In the past, the magnetic layer was usually made of ferromagnetic or ferrimagnetic materials, whose magnetization switching or detection are relatively definite and easy to realize.

Contents of the invention

The object of the present invention is to provide a memory unit based on in-plane magnetized ferromagnetic material in order to further improve the magnetic moment reversal speed and storage stability of the traditional magnetic memory.

An in-plane magnetized antiferromagnetic random access memory unit, which includes an antiferromagnetic layer, a heavy metal layer, and a first group of terminals connected to the heavy metal layer and a second group of terminals, the first group of terminals is used to connect a pulse current source, The second set of terminals is used to connect a voltage source, and the magnetization state of the antiferromagnetic layer is in-plane magnetization.

The antiferromagnetic layer in the above-mentioned information storage point is a rare earth-transition metal (RE-TM) amorphous alloy, and its rare earth (RE) element is one of Tb, Gd, and Ho elements, and the transition metal (TM) It is one of Co, Fe, Ni elements.

An in-plane magnetized antiferromagnetic random access memory unit, when using it for data storage, comprises the following steps:

1) Connecting the first set of endpoints of the heavy metal layer in the antiferromagnetic information storage point to a pulse current source;

2) When it is necessary to rewrite the magnetization state in the antiferromagnetic information storage point, a pulse current is passed through the first group of terminals;

3) Make the spin current generated by the pulse current enter the antiferromagnetic layer from the heavy metal layer, and drive the magnetization direction to rotate in the plane.

The pulse current is continuously fed, so that the pulse current generates a continuous spin flow into the antiferromagnetic layer 4, driving the magnetization direction to continuously rotate in the plane, so that every time the magnetic moment of the transition metal in the antiferromagnetic layer 4 rotates continuously At 90 degrees, the magnetic resistance value R _H will change from positive to negative, or from negative to positive. When the magnetic resistance value R _H is positive, the state value of the memory cell is defined as 1; the magnetic resistance value R _H When it is a negative value, the state value of the storage unit is defined as 0.

When acquiring the stored data in the antiferromagnetic information storage point, connect the second group of terminals of the heavy metal layer to a voltage source, pass a test current through the first group of terminals, and measure its abnormal Hall resistance value at the second group of terminals , by judging whether the value is positive or negative, the status value of the storage unit is obtained.

A protective layer is provided on the antiferromagnetic layer; the material of the protective layer is silicon dioxide, magnesium oxide, aluminum oxide, tantalum pentoxide and other oxides, or silicon nitride, aluminum nitride, titanium nitride, etc. nitride.

The above-mentioned first group of endpoints and the second group of endpoints are arranged vertically to each other and connected to the heavy metal layer.

The heavy metal layer is a metal layer formed of one of the non-magnetic heavy metals, or a metal layer formed of one of the non-magnetic heavy metals and a transition metal.

The aforementioned nonmagnetic heavy metals include Ta, W, Pt, Au, and Ir.

By adopting the above-mentioned technical solution, this patent has the following technical effects;

The in-plane magnetized antiferromagnetic random access memory unit has higher magnetic moment switching speed, better storage stability, non-volatility, no external magnetic field, easy miniaturization, and low energy consumption. Anti-interference, good durability, this storage unit is especially faster in read and write speed. In addition, compared with the first-generation MRAM and STT-MRAM, there are only two layers of functional film, and there is no difficulty in preparing an ultra-thin insulating layer, and the manufacturing process is simplified.

Description of drawings

Fig. 1 and Fig. 2 are the structural representations of storage unit among the present invention;

Fig. 3 is a schematic diagram of the variation of the in-plane magnetized antiferromagnetic layer planar Hall resistance with the rotation of the magnetization direction in the present invention;

Fig. 4 is a schematic diagram of the in-plane magnetic moment direction and the electric current and the spin current direction in the heavy metal layer in the antiferromagnetic layer TbCo in the present invention;

Fig. 5 is the change schematic diagram of pulse current among the present invention;

Fig. 6 is a schematic diagram of the variation of planar Hall resistance with pulse current in the present invention;

Fig. 7 is a schematic diagram of the rotation of the magnetization direction of the non-collinear in-plane magnetized antiferromagnetic RE-TM under the action of SOT in the present invention.

Detailed ways

A kind of in-plane magnetization antiferromagnetic random access memory storage unit, it comprises antiferromagnetic layer 4, and the first group of terminals 6 and the second group of terminals 7 connected with antiferromagnetic layer 4, the first group of terminals 6 is used for A pulse current source is connected, the second group of terminals 7 is used for connecting a voltage source, and the magnetization state of the antiferromagnetic layer 4 is in-plane magnetization.

Specifically, the antiferromagnetic layer 4 in the information storage point 1 is a rare earth-transition metal (RE-TM) amorphous alloy, and its rare earth (RE) element is one of Tb, Gd, and Ho elements, and the transition metal (TM) is one of Co, Fe, Ni elements, the thickness of the antiferromagnetic layer is 1nm-100nm, it is used to store information; the material of the heavy metal layer 3 is Pt, Au, Ta, W, Ir and other non-magnetic heavy metals A kind of, or their non-magnetic alloy formed with other transition group metals, its thickness is 1nm-500nm, its function is to generate a large spin current; the covering protective layer 5 in the information storage point 1 is silicon dioxide, oxide Oxides such as magnesium, aluminum oxide, and tantalum pentoxide, or nitrides such as silicon nitride, aluminum nitride, and titanium nitride, are used to prevent oxidation of the rare earth-transition metal alloy layer, and the thickness is 1nm-20nm; information storage The geometric scale of point 1 is 3nm-3000nm.

An in-plane magnetized antiferromagnetic random access memory unit, when using it for data storage, comprises the following steps:

1) Connect the first group of terminals 6 of the heavy metal layer 3 in the antiferromagnetic information storage point 1 to the pulse current source;

2) When it is necessary to rewrite the magnetization state in the antiferromagnetic information storage point 1, a pulse current is passed through the first group of terminals 6;

3) The spin current generated by the pulse current enters the antiferromagnetic layer 4 from the heavy metal layer 3 to drive the magnetization direction to rotate in the plane.

The pulse current is continuously fed, so that the pulse current generates a continuous spin flow into the antiferromagnetic layer 4, driving the magnetization direction to continuously rotate in the plane, so that every time the magnetic moment of the transition metal in the antiferromagnetic layer 4 rotates continuously At 90 degrees, the magnetic resistance value R _H will change from positive to negative, or from negative to positive. When the magnetic resistance value R _H is positive, the state value of the memory cell is defined as 1; the magnetic resistance value R _H When it is a negative value, the state value of the storage unit is defined as 0.

When obtaining the storage data in the antiferromagnetic information storage point 1, the second group of terminals 7 of the heavy metal layer 3 is connected to the voltage source, and the test current is passed through the first group of terminals 6, and its voltage is measured at the second group of terminals 7. Abnormal Hall resistance value, by judging the positive and negative changes of the value, the state value of the memory cell can be obtained.

On the antiferromagnetic layer 4, a protective layer 5 is provided; the material of the protective layer 5 is silicon dioxide, magnesium oxide, aluminum oxide, tantalum pentoxide and other oxides, or silicon nitride, aluminum nitride, nitrogen Titanium oxide and other nitrides are used to prevent oxidation of the rare earth-transition metal alloy layer.

The first group of endpoints 6 and the second group of endpoints 7 are arranged perpendicular to each other and connected to the heavy metal layer 3 .

The heavy metal layer 3 is a metal layer formed by one of the nonmagnetic heavy metals, or a metal layer formed by one of the nonmagnetic heavy metals and a transition metal, with a thickness of 1nm-500nm, and the nonmagnetic heavy metals include Ta , W, Pt, Au, Ir.

A substrate 2 is provided on the other side of the middle part of the first group of terminals 6 and the second group of terminals 7 . Among them, the length and width of the information storage point 1 range from 3nm to 3000nm

In the present invention, the magnetization state of the antiferromagnetic memory unit can be adjusted and controlled by pulse current to complete the writing of information under the condition of no external field, and at the same time, its magnetization state can also be detected by the abnormal Hall resistance to complete the readout of information , to achieve the purpose of writing and reading information, and realize the function of information storage.

Example

Fabricate in-plane magnetized antiferromagnetic random access memory storage unit on thermal oxide silicon substrate, preparation of in-plane magnetization antiferromagnetic magnetic random access memory storage unit: use thermal oxide silicon substrate with length 10mm, width 10mm, thickness 0.5mm After ultrasonic cleaning with acetone, ultrasonic cleaning with deionized water, and finally ultrasonic cleaning with absolute ethanol. The cleaned substrates were blown dry with high-purity nitrogen gas. Coat the photoresist positive resist on the substrate, expose the cross-hair pattern shown in Figure 1 with an electron beam, wash off the exposed part, put the substrate into the coating chamber of the magnetron sputtering coating equipment, and place the coating chamber Pump to a vacuum of 1×10 ^-5 Pascal. Then fill the working gas to 0.8 Pascal argon, deposit a 10 nm thick Pt film on the substrate by DC magnetron sputtering method, then take it out, wash off the photoresist, at this time, the writing current line and the reading current line are formed. measuring line. Coat the photoresist positive resist on the substrate again, and use the electron beam to expose the information storage point (1) pattern shown in Figure 1. After the exposed part is washed off, the substrate is placed on the coating of the magnetron sputtering coating equipment Indoor, pump the coating chamber to a vacuum of 1×10 ^-5 Pascal. Then the substrate is heated up to 300 degrees, and a strong magnetic field of 0.2 Tesla is applied in the direction parallel to the film surface to promote the magnetization direction of the TbCo film to remain in the plane, and then fill the working gas with argon gas of 0.8 Pascal, and use radio frequency magnetic Controlled sputtering method deposits 6 nanometers thick in-plane magnetized TbCo film and 1 nanometer thick aluminum oxide film on the substrate, and washes off the photoresist after taking it out. At this time, the cross-shaped write current line and readout measurement line, The preparation of the information storage point and the information storage point has been completed, forming an in-plane magnetized antiferromagnetic random access memory storage unit.

A pulse current of 1 mA and a width of 1 μs is passed into the write current line. After a pulse is passed, a detection current of 0.1 μA is passed through the write current line, and the voltage is measured on the readout measurement line. The resistance is a plane Ho Er resistance (voltage divided by the detection current value), the result is shown in Figure 6. When the magnetic moment rotates 90 degrees in the plane, the planar Hall resistance gradually changes from positive to negative, or from negative to positive. Then changing the direction of the pulse current can reverse the direction of the magnetic moment in the TbCo film. The process of passing in the pulse current is the process of writing information, and the process of passing in the detection current is the process of reading out the information. The positive and negative of the planar Hall resistance correspond to 0 or 1 of the information respectively.

Claims (7)

1. An in-plane magnetized antiferromagnetic random access memory unit, characterized in that: it includes an information storage point (1), and the information storage point (1) includes an antiferromagnetic layer (4), a heavy metal layer (3), The first group of terminals (6) connected to the heavy metal layer (3) and the second group of terminals (7) connected to the heavy metal layer (3), the first group of terminals (6) are used to connect the pulse current source, the second group of terminals (7) It is used to connect a voltage source, and the magnetization state of the antiferromagnetic layer (4) is in-plane magnetization; When storing data, the following steps are included: 1) Connect the first set of endpoints (6) of the heavy metal layer (3) in the information storage point (1) to the pulse current source; 2) When it is necessary to rewrite the magnetization state in the information storage point (1), pass a pulse current into the first group of terminals (6); 3) Make the spin current generated by the pulse current enter the antiferromagnetic layer (4) from the heavy metal layer (3), and drive the magnetization direction to rotate in the plane. 2. The in-plane magnetized antiferromagnetic random access memory unit according to claim 1, characterized in that: the antiferromagnetic layer (4) in the information storage point (1) is a rare earth-transition metal RE-TM Amorphous alloy, the rare earth RE element is one of Tb, Gd, Ho elements, and the transition metal TM is one of Co, Fe, Ni elements. 3. The in-plane magnetized antiferromagnetic random access memory unit according to claim 1, characterized in that: the heavy metal layer (3) in the information storage point (1) is a heavy metal element layer with a large spin Hall angle , whose elements are Ta, W, Pt, Au, Ir, one of these non-magnetic heavy metals, or their non-magnetic alloys formed with other transition metals. 4. The in-plane magnetized antiferromagnetic random access memory unit according to claim 1, characterized in that: the pulse current is continuously passed in, so that the pulse current generates a continuous spin current and enters the antiferromagnetic layer (4), Drive the magnetization direction to rotate continuously in the plane, so that whenever the magnetic moment of the transition metal in the antiferromagnetic layer (4) rotates continuously by 90 degrees, the magnetoresistance value R _H will change from positive to negative, or from negative to negative. To positive, when the magnetic resistance value R _H is positive, the state value of the memory cell is defined as 1; when the magnetic resistance value R _H is negative, the state value of the memory cell is defined as 0. 5. The in-plane magnetized antiferromagnetic random access memory unit according to claim 1, characterized in that: when acquiring the stored data in the information storage point (1), the second group of endpoints of the heavy metal layer (3) (7) Connect with the voltage source, pass the test current at the first group of terminals (6), and measure the abnormal Hall resistance value at the second group of terminals (7), and obtain the storage by judging the positive and negative changes of the value The state value of the unit. 6. The in-plane magnetized antiferromagnetic random access memory unit according to claim 1 or 2 or 3 or 4 or 5, characterized in that: a protective layer (5) is provided on the antiferromagnetic layer (4) . 7. The in-plane magnetized antiferromagnetic random access memory unit according to claim 1 or 2 or 3 or 4 or 5, characterized in that: the first group of endpoints (6) and the second group of endpoints (7) are perpendicular to each other Set, connected with the heavy metal layer (3) respectively.

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