CN110581214B

CN110581214B - Composite multilayer magnetic nanoring array memory device and preparation method and application thereof

Info

Publication number: CN110581214B
Application number: CN201910874078.9A
Authority: CN
Inventors: 任杨; 张林林; 和孝东; 高健文; 周小卫; 刘铸
Original assignee: Yunnan University YNU
Current assignee: Yunnan University YNU
Priority date: 2019-09-17
Filing date: 2019-09-17
Publication date: 2021-01-12
Anticipated expiration: 2039-09-17
Also published as: CN110581214A

Abstract

The invention provides a composite multilayer magnetic nanoring array memory device and a preparation method and application thereof, wherein the composite multilayer magnetic nanoring array memory device comprises a substrate made of an insulating material and a double-layer rectangular nanoring array attached to the substrate, wherein the double-layer rectangular nanoring array comprises a multilayer magnetic material with vertical anisotropy as a lower layer material and a soft magnetic material with in-plane anisotropy as an upper layer material; the upper layer rectangular nano ring array structure and the lower layer rectangular nano ring array structure are concentric equal-size rectangular nano ring arrays; the length-width ratio of the outer frame of the rectangular nanoring is 2:1, the length of the long side is l, the width of the ring is w, the distance between the rectangular nanorings is s, and the thickness of the bottom layer is d₁The thickness of the upper layer is d₂，l∈(200nm，2um)，w∈(35nm，360nm)，d₁∈(5nm，15nm)，d₂E (20nm, 40nm), w is l e (0.1, 1). The invention can greatly reduce the reversal field, greatly increase the selection range of the reversal field, and obtain more modulatable magnetic domain states, thereby providing more choices for encoding and decoding of magnetic recording writing.

Description

Composite multilayer magnetic nanoring array memory device and preparation method and application thereof

Technical Field

The invention relates to the field of magnetic device production, in particular to a preparation method and application of a composite multilayer magnetic nanoring array memory device.

Background

The magnetic nanoring device has stable characteristic magnetic domain 'vortex state' and ultrahigh storage density, so that the excellent performance of the magnetic nanoring device is widely applied to high-density magnetic storage media, magnetic random access memories, magneto-resistive reading heads, spinning devices, magnetic sensors, magnetic switching devices and the like. Magnetic Random Access Memory (MRAM) structures typically consist of two ferromagnetic layers (a free layer and a fixed layer) and a conducting nonmagnetic layer or an insulating layer setAnd (4) obtaining. In these heterostructures, the memory state is determined by the relative magnetization directions of the free and fixed layers. The magnetic moment in the fixed layer is fixed in one direction, but the magnetic moment in the free layer is free to rotate. Thus, the memory state of an MRAM can be determined by the magnetic structure of the free layer. Free layers are typically fabricated into nanostructures, and thus their magnetic structure and inversion mechanism depend on the configuration and size of the nanostructure, which can affect the competition results of magnetostatic energy and exchange energy. The classical nanostructure, the magnetic nanoring, can form a closed magnetic domain state under a magnetic field, which is generally called a vortex state, and the vortex state is easy to form a stable and controllable magnetic domain state. There are also related patent documents reported, for example, the application of a controllable magnetic domain coupling rounded rectangular double nanoring device disclosed in chinese patent CN105845823B in MRAM. A ring-shaped memory element is disclosed in US7002839B 2. In general, it is difficult to modulate the inversion field of an isotropic magnetic nanoring array with good symmetry and its corresponding characteristic magnetic domains, and the modulatable magnetic domain state is too single. United states patentUS7846642B2The disclosed storage element can realize anisotropic modulation of the inversion field of a magnetic device by means of exchange elastic coupling, a spin valve structure, an asymmetric nanoring array and the like.

In recent years, oblique magnetic recording has attracted much attention as a new magnetic recording means. The film structure comprises a multilayer magnetic film formed by coupling a hard magnetic layer with strong perpendicular anisotropy and a soft magnetic layer with in-plane anisotropy, the interface of the multilayer magnetic film presents exchange elastic coupling behavior, and a large range for realizing the oblique magnetic anisotropy is provided. In addition, the Tilted Magnetization Anisotropy (TMA) obtained by the exchange elastic coupling effect of the interface plays an important role in the development of nano Spin Torque Oscillators (STO) and three-dimensional electronic compasses. Implementing TMA in the above system can significantly reduce the critical reversal current density of current-induced magnetization reversal and the reversal time in STO.

In summary, combining the advantages of exchange elastic coupling and magnetic nanorings, the magnetic domain state and the inversion field of the nanostructure can be controlled, and richer magnetic domain state and anisotropic modulation of magnetization and magnetization reversal behavior can be obtained. However, to date, the effect of exchange elastic coupling on the magnetic domain state of magnetic nanorings has been relatively studied.

Disclosure of Invention

The invention provides a composite multilayer magnetic nanoring array memory device.

The composite multilayer magnetic nanoring array memory device comprises a substrate made of an insulating material and a structure attached to the substrate, wherein the structure is a double-layer rectangular nanoring array, and the double-layer rectangular nanoring array comprises a multilayer magnetic material with vertical anisotropy as a lower layer material and a soft magnetic material with in-plane anisotropy as an upper layer material; the lower layer material is directly attached to the substrate, and the upper layer material grows on the lower layer material; the upper layer rectangular nanoring array structure formed by the upper layer material and the lower layer rectangular nanoring array structure formed by the lower layer material are concentric equal-size rectangular nanoring arrays;

the length-width ratio of the rectangular nanoring outer frame is 2:1, the length-side length is l, the ring width is w, the distance between the rectangular nanorings is s, and the thickness of the bottom layer is d₁The thickness of the upper layer is d₂Wherein: l is belonged to (200nm, 2um), w is belonged to (35nm, 360nm), d₁∈(5nm，15nm)，d₂∈(20nm，40nm)，w:l∈(0.1，1)。

The change of the spacing s between the rectangular nano rings (the change range is from w to 2000nm) does not affect the coercive force and the distribution of the reversal field, and the specific scheme is as follows: s ∈ (w, 1200 nm).

The preparation method of the composite multilayer magnetic nanoring array memory device comprises the following steps: the method comprises the steps of forming a required template on a material of a substrate, firstly depositing a hard magnetic material with vertical anisotropy on the template to form a lower rectangular nanoring array, then depositing a soft magnetic material with in-plane anisotropy on the template to form an upper rectangular nanoring array, and directly coupling the upper and lower layers of magnetic materials together through an interface.

Furthermore, the method for preparing the template on the substrate is one of a deep ultraviolet lithography technology, an electron beam exposure technology and a nano-imprinting technology; the method for forming the nano-ring array by deposition on the template is one of a magnetron sputtering technology, an electron beam evaporation technology and a pulse laser deposition technology.

The substrate is made of any one of a silicon wafer, a silicon oxide wafer, an ITO glass substrate, an FTO glass substrate, a K9 glass substrate, a quartz glass substrate, a sapphire single crystal wafer and a gallium arsenide substrate.

Wherein the lower layer material is vertically anisotropic (Co/Pd)_nMultilayer film, (Co/Pt)_nOne of a multilayer film, FeCo/Pt multilayer film, FePt alloy and CoPt alloy, having a perpendicular anisotropy constant K_u∈(5×10⁶erg/cm³,6×10⁷erg/cm³) (ii) a The upper layer material is a soft magnetic material, which is a magnetic material with low coercive force and high magnetic permeability.

Preferably, the upper layer material is a single-layer film structure formed by one of NiFe, CoFe, CoFeB, Fe, Co and Ni, or an alloy or multi-layer film structure formed by a plurality of materials.

The lower magnetic material being of perpendicular anisotropy (Co/Pd)_nMultilayer film, (Co/Pt)_nOne of a multilayer film, FeCo/Pt multilayer film, FePt alloy and CoPt alloy, having a perpendicular anisotropy constant K_u∈(5×10⁶erg/cm³,6×10⁷erg/cm³) Preferably (Co (0.5)/Pd (3))₈. The upper layer magnetic material is a soft magnetic material, which means a magnetic material with low coercive force and high magnetic permeability, for example: a single layer film structure formed by one of NiFe, CoFe, CoFeB, Fe, Co and Ni or an alloy or a multi-layer film structure formed by a plurality of materials, such as CoFe/NiFe, and the like, preferably Ni_0.81Fe_0.19。

The specific scheme is as follows: for example, the substrate material is a silicon wafer, the silicon wafer is placed on a spin coater, the silicon wafer is dripped with photoresist and then is subjected to spin coating to obtain a uniform adhesive layer, the silicon wafer coated with the adhesive layer is subjected to post-baking, a 248-nanometer deep ultraviolet exposure machine is used for exposure and development and fixation to obtain a rectangular nano-dot array structure with a required shape, evaporation of a magnetic material with vertical anisotropy is carried out in the rectangular nano-dot array structure by a magnetron sputtering method, and then the photoresist is removed to obtain the magnetic nano-dot array structure with the required shape.

The invention also provides application of the composite multilayer magnetic nanoring array memory device, in particular to application in a magnetic random access memory, a magnetic nano switch device, a magnetic spin device and a magnetic sensor.

The composite multilayer magnetic nanoring array memory device can be applied to a structure consisting of a pair of magnetic rings (low inversion field and high inversion field magnetic nanorings respectively) with different inversion fields as a low inversion field magnetic nanoring, and a nonmagnetic layer ring is arranged between the pair of magnetic rings. Thus, the magnetic structure unit is composed of a composite magnetic multilayer nanoring/nonmagnetic layer/high inversion field magnetic ring in which inversion fields of the pair of magnetic rings are different from each other, so that a magnetic sensor or a magnetic memory cell can be formed. In this case, the giant magnetoresistive GMR element can be obtained by a conductive nonmagnetic layer such as Cu, Ru, Al, Au, and Cr, or by a conductive nonmagnetic layer such as Al₂O₃And an insulating layer such as MgO forms a tunneling magneto-resistance TMR element.

The invention provides a composite multilayer magnetic nanoring array storage device and a preparation method and application thereof, based on a composite magnetic multilayer film structure which selects a magnetic material with high vertical anisotropy as a bottom layer of a nanoring array and a soft magnetic material with in-plane anisotropy as an upper layer of the nanoring array, based on the structure, discloses anisotropy modulation of the vertical anisotropy of a lower layer material on magnetization and reverse magnetization behaviors of a soft magnetic nanoring and influence of a size effect of a nanoring lattice on a reverse field and a magnetic domain state, and provides a basis for development of a magnetic nanoring device.

The devices prepared by the invention all have in-plane magnetic anisotropy. With respect to a single-layer soft magnetic nanoring, the magnetic hysteresis loop has only two inverse fields corresponding to two magnetic domain states, namely, an onion state and a vortex state, and for any particular device of the present invention meeting the above-described conditions, the device is first placed on the film surfaceParallel external magnetic field H₁After saturation magnetization is achieved, the magnetic field is slowly reduced to 0 (method I), and then in-plane magnetic field scanning is applied, so that three reversal fields can appear in the obtained hysteresis loop and correspond to three specific magnetic domain states. The distance between the nanorings, the length-width ratio of the nanorings and the width of the fixed nanorings are fixed, only the length l of the long side of the nanorings is changed, and the sizes of the corresponding three inversion fields can be modulated. And for any one of the devices of the present invention satisfying the above conditions, the first step is to make the device in an external magnetic field H perpendicular to the film surface₂After saturation magnetization, the magnetic field is slowly reduced to 0 (method II), and then an external magnetic field is applied to the film surface for scanning in the second step, and the magnitude of the three reverse fields is changed relative to the result of the method I (both the methods I and II require the external magnetic field H)₁And H₂Greater than its effective anisotropy field). The composite multilayer magnetic nanoring array device provided by the patent of the invention can greatly reduce the reversal field, greatly increase the selectable range of the reversal field, and obtain more modulatable magnetic domain states, thereby providing more choices for encoding and decoding of magnetic recording writing.

Drawings

FIG. 1a is a scanning electron micrograph of an example device I with a rectangular long side l of 870 nm ring array device;

FIG. 1b is a scanning electron micrograph of a ring array device with a rectangular long side l of 1050 nm according to an embodiment device II;

FIG. 1c is a SEM image of a 1220 nm rectangular ring array device with a long side l of an embodiment device III;

FIG. 1d is a schematic diagram of the shape of an example rectangular nanoring device;

FIG. 1e is a schematic structural diagram of an example composite multilayer rectangular nanoring device;

fig. 2a is a hysteresis loop diagram of a corresponding single-layer magnetic nanoring with l 1050 nm as a reference;

FIG. 2b is a hysteresis loop diagram of a typical nanodot device of device II of the example;

FIG. 3a is a graph of the magnitude of the inversion field of a reference NiFe nanoring as a function of the length l of the nanoring long side;

FIG. 3b is a graph showing the relationship between the magnitude of the inversion field of a reference CoPd multilayer nanoring and the change of the length l of the long side of the nanoring;

fig. 3c shows the inversion field H for the example device at 0 °_sw1And H_sw1’；

Fig. 3d shows the inversion field H for the example device with θ equal to 90 °_sw2And H_sw2’；

FIG. 3e shows the inversion field H of the device of the example_sw3And H_sw3’A relation graph which changes along with the length l of the long edge of the nanoring;

fig. 4a is a magnetic domain diagram of an example device ii at H-0 with θ -0 °;

fig. 4b is a domain diagram for an example device ii at H200 Oe with θ 0 °;

fig. 4c is a domain diagram for an example device ii at H300 Oe with θ 0 °;

FIG. 5a is a schematic diagram of a circuit configuration of an array device for a magnetic random access memory of an embodiment;

FIG. 5b is a schematic diagram of a specific circuit structure of a single device of an embodiment;

FIG. 6a is a schematic diagram of a write apparatus for a magnetic random access memory according to an embodiment of the present invention;

FIG. 6b is a schematic diagram of a read-out apparatus for a magnetic random access memory according to an embodiment of the device.

Detailed Description

In order that the objects and advantages of the invention will be more clearly understood, the following description is given in conjunction with the accompanying examples. It is to be understood that the following text is merely illustrative of one or more specific embodiments of the invention and does not strictly limit the scope of the invention as specifically claimed.

The present invention will be explained in detail with reference to examples.

Device fabrication example

Cutting the silicon wafer into 20 × 10mm²Size (silicon wafer main parameters: P type, resistivity:<0.0015>the crystal orientation:<100>thickness: 500um), cleaning silicon chip, placing into ovenBaking at 150 deg.C for 30 min in oven, taking out, placing on spin coater, sucking out appropriate amount of deep ultraviolet photoresist with suction tube, dripping silicon wafer (XAR-P5800/7), spinning at 5000 rpm for 60 s, taking off silicon wafer, placing in oven, baking at 85 deg.C for 45 s, and taking out. Placing the silicon wafer after glue homogenizing into a maskless far ultraviolet exposure machine with the wavelength of 248 nanometers, wherein the exposure dose is 30mJ/cm²And exposing the designed coupling nano ring pattern on a silicon chip by using a positive photoresist process. And taking out the silicon wafer, putting the silicon wafer into a developing solution for developing for 50 seconds, then putting the silicon wafer into a fixing solution for 45 seconds, washing the silicon wafer by deionized water, drying the surface of the silicon wafer by using nitrogen, and adjusting the magnification to be 100 times by using a microscope to observe whether the pattern of the nano-ring array is clear. Placing the silicon wafer with the nanoring array and clear pattern into a magnetron sputtering instrument, setting Ar gas pressure at 5mTorr and high vacuum at 5 × 10^-8Torr, Ta (5)/Pd (5)/(Co (0.5)/Pd (3))₈(nano) multilayer film on silicon chip, then continuously sputtering Ni_0.81Fe_0.19(25) The (nano) film was on a silicon wafer, which was finally covered with 5nm Au as a protective layer. And taking out the silicon wafer from the magnetron sputtering instrument, soaking the silicon wafer in OK73 solution for 30 minutes, then placing the silicon wafer in ultrasound for several seconds to observe that the photoresist completely falls off, washing the silicon wafer by using deionized water, and drying the silicon wafer by using nitrogen to obtain a corresponding device. The preparation example of the invention prepares various types of devices, wherein scanning electron micrographs of three devices of a representative typical structure are respectively shown in fig. 1a, fig. 1b and fig. 1 c. Six devices are all prepared, all the device structures are consistent, and only the length l of the long side of the rectangle is changed. All the devices are rectangular nanoring arrays, the edge distance s between the fixed rectangular nanorings is 450 nanometers, the width w of the fixed nanorings is 300 nanometers, the length-width ratio of a rectangular outer frame of the fixed rectangular nanorings is 2:1, only the length l of the long edges of the nanorings is modulated, wherein the values of l are 870 nanometers, 960 nanometers, 1050 nanometers, 1120 nanometers, 1220 nanometers and 1630 nanometers respectively, and the side edges of the nanorings are provided with rounded fillets.

FIG. 1d is a schematic diagram of a shape of a rectangular nanoring device according to an embodiment, where the edge distance between the rectangular nanoring and the nanoring is s, the nanoring width is w, the long edge length is l, and the aspect ratio of the outer frame of the fixed rectangular nanoring is 2: 1;

FIG. 1e is a schematic structural diagram of the composite multilayer rectangular nanoring device according to the embodiment, in which the next material is CoPd, the upper material is NiFe, and the applied saturation field angle is θ.

The longitudinal and polar micro-focusing magneto-optical kerr effect instruments are used for detecting one typical composite magnetic multilayer nano-ring array device (device II) and the corresponding single-layer nano-ring structure thereof, so that a hysteresis loop corresponding to each device can be obtained, and the results are shown in fig. 2a and fig. 2 b. FIG. 2a is a hysteresis loop diagram of a corresponding single-layer magnetic nanoring of 1050 nm where the solid diamond-shaped connection is Si substrate/Ta (5)/Pd (5)/(Co (0.5)/Pd (3))₈A magnetic hysteresis loop diagram of Au (5) (nanometer) single-layer magnetic nanoring (CoPd multi-layer nanoring) with external scanning magnetic field perpendicular to the film surface, wherein the solid dot line diagram is Si substrate/Ta (5)/Ni_0.81Fe_0.19(25) A magnetic hysteresis loop diagram of Au (5) (nanometer) single-layer magnetic nanoring (NiFe nanoring for short) with the scanning external magnetic field parallel to the film surface; fig. 2b is a hysteresis loop diagram of a typical nanodot device of the device ii of the present invention, in which a solid square dot line diagram is a hysteresis loop obtained by slowly lowering an external field to 0 (hereinafter, referred to as θ ═ 0 °) after saturation magnetization of the device in an external magnetic field of 1.5 tesla parallel to the film surface, and then applying in-plane magnetic field scanning, and a triangular dot line diagram is a hysteresis loop obtained by slowly lowering an external field to 0 (hereinafter, referred to as θ ═ 90 °) after saturation magnetization of the device in an external magnetic field of 1.5 tesla perpendicular to the film surface, and then applying in-plane magnetic field scanning.

FIG. 2b shows that the hysteresis loop of the single-layer CoPd multilayer nanoring corresponding to the device II has good vertical anisotropy and coercive force H_cAbout 995Oe, the hysteresis loop of the corresponding single-layer NiFe nanoring shows good in-plane anisotropy, the hysteresis loop has two steps, and the two steps corresponding to the two inversion fields H are obtained by differentiating to obtain an inflection point_sw1And H_sw2The transition fields of the normal onion state-vortex state and vortex state-reverse onion state respectively have the size of about 44Oe and 286Oe respectively. And the magnetic hysteresis loop and the reverse field of the composite magnetic nano-ring device corresponding to the magnetic hysteresis loopThe situation of (a) is relatively greatly changed. When θ is 0 °, the hysteresis loop has three steps, each H_sw1＝-121Oe、H_sw265Oe and H_sw3355 Oe; when θ is 90 °, the hysteresis loop also exhibits three steps, H_sw1’The case of-120 Oe is very close to the case of θ 0 °, but H_sw2’127Oe, the value relative to H_sw2Increased by nearly one time, finally H_sw3’376Oe, relative to H_sw3Also increased by approximately 20 Oe. Therefore, the device II is subjected to saturation magnetization under external fields in different directions, the exchange elastic coupling of the interface of the device II can provide the gradient magnetic anisotropy in different directions, and the magnetic domain state of the composite magnetic nanoring under different scanning fields can be modulated, so that the inversion field is changed.

Fig. 3 a-3 e show the modulation relationship between the inversion field of six composite multilayer magnetic nanoring array memory devices and their corresponding single-layer magnetic nanorings and the length of the long side of the nanorings. It can be seen from FIG. 3a that for the NiFe nanoring, its inversion field H_sw1The variation is not large with the increase of l, the variation range is between 40Oe and 60Oe, and H_sw2The l is increased rapidly, and when l is more than or equal to 960 nanometers, the change is not large. However, for the CoPd multilayer nanoring in FIG. 3b, the inversion field rapidly decreases with the increase of l, and the value change is small when l ≧ 1220 nm. Fig. 3c, 3d, and 3e correspond to the inversion fields H when θ is 0 ° and θ is 90 °, respectively_sw1、H_sw2And H_sw3And H_sw1’、H_sw2’And H_sw3’Graph of the relationship with l. First, for the case where θ is 0 °, H_sw1With increasing l, the value of l is almost constant, and after l is greater than 1120 nm, the value is rapidly reduced, and finally the value is slowly reduced with the increasing l. H_sw1’With l and H_sw1The situation is almost consistent with the change of l. H_sw1And H_sw1’The corresponding is the transition field from the positive onion state to the vortex state, which indicates that: when l is larger than 1120 nm, the tilted magnetic anisotropy and the size effect do not influence the transition field from the onion state to the vortex state greatly. Second, H_sw2With increasing lLarge, with little variation in value ranging from 62Oe to 71Oe, and H_sw2’The value of the reversed field is almost unchanged when l is more than or equal to 1220 nanometers. While for different values of theta the field is reversed H_sw2’Ratio H_sw2The increase of the value by about one time indicates that the influence of the gradient magnetic anisotropy on the transformation field is large, and the size effect of the nanoring corresponds to H in the case where θ is 90 DEG_sw2’When the angle theta is changed to be larger than 0 degrees, the inversion fields of two corresponding single-layer structures (the NiFe nano-ring and the CoPd multi-layer nano-ring) of the composite magnetic nano-ring are hardly changed along with the change of l after l is more than or equal to 1220 nanometers, so that H is hardly changed by increasing l_sw2And H_sw2’. Finally, H_sw3The value of l varies little with increasing l, ranging from 323Oe to 363Oe, while H_sw3’The value of l increases from 365Oe to 477 Oe. The third inversion field, which illustrates both cases, is also strongly influenced by the tilt magnetic anisotropy and the size effect. In summary, when comparing the case where θ is 0 ° and the case where θ is 90 °, it can be seen that the inversion field H is generated when θ is 90 °_sw2’And H_sw3’As the change of l is larger than the case where θ is 0 °, the amounts of change are 37.1% and 30.7%, respectively, which indicates that the range in which the inversion field can be modulated is larger when θ is 90 ° than 14.5% and 12.3% in the case where θ is 0 °. And, the value of the second inversion field is 244Oe, which is about twice as large as the value of the second inversion field in the case of θ of 90 ° in the device II of the present invention, with respect to the NiFe single-layer nanoring, and the inversion field distribution of the NiFe single-layer nanoring (i.e., H)_sw1-H_sw2，The value of which corresponds to the degree of swirl stability) is almost equal to the degree of swirl stability of the device II of the present invention at θ ═ 90 °, which indicates that the device II of the present invention not only has the advantage of low power consumption for writing but also ensures the degree of swirl stability at θ ═ 90 °.

The domain structure at different scan fields was observed for device II with θ equal to 0 °. When θ is 0 °, the scanning field H is 0Oe, and it can be seen that the magnetic domain top layer forms a vortex state, because the magnetization of the bottom layer perpendicular to the film surface direction is weak, and the influence on the top layer is small; when H is 200Oe, the magnetic domain presents a left onion state; when H is 300Oe, the left onion state shifts slightly, forming the lower left onion state. Compared with a single-layer nanoring, the magnetic domain structure has more transition from a vortex state to a left onion state, thereby further explaining the modulation of the magnetic domain state by the exchange elastic coupling. From the magnetic domain diagrams of fig. 4a, 4b, and 4c, the influence of the tilted magnetic anisotropy caused by the exchange elastic coupling on the magnetic domain state can be seen, thereby revealing the mechanism of the occurrence of three inversion fields corresponding to the transition of the positive onion state-vortex state, vortex state-left onion state, and left onion state-inverted onion state, respectively. For reading and writing of magnetic random access memory, the unit of nanoring magnetic memory can be respectively defined as "0" and "1" by the difference of the rotation direction of the vortex state. For the device of the patent, the vortex state and the left onion state can be respectively defined as '0' and '1', and the inversion field from the vortex state to the left onion state can be greatly reduced due to the modulation of exchange elastic coupling, which is beneficial to the magnetic recording mode with low energy consumption; and the left onion state and the inverted onion state can define more new compiling codes, so that multiple choices are provided for reading and writing compiling of the magnetic random access memory, and the switching field selection of the magnetic switching device can be increased.

Application example:

fig. 5a and 5b are a circuit configuration diagram of a magnetic random access memory cell and a configuration diagram of a magnetic memory cell, respectively, as an example of the application device II. As shown in FIG. 5a, the circuit includes a sense line 1, a bit line 2, a word line 3, an access transistor 4, a composite magnetic nanoring cell 5 of the invention, and a sense amplifier 6. FIG. 5b is a schematic diagram of the composition and circuit structure of a single magnetic memory cell. Fig. 6a and 6b are schematic views of a writing and reading device, respectively. As shown in fig. 6a, the CoFe layer 7, the MgO layer 8, and the NiFe layer 9 are first designed to be saturated and magnetized when θ is 90 °, and then current is applied to the composite magnetic nanoring memory cell, the current is lower than the current threshold capable of destroying the vortex structure of the CoFe layer, so that signals are written into the memory cell, after the current is applied to the bit line and the word line, the bias signal in the sense line is "0", and the access transistor channel is turned off, so that the direction of the vortex rotation of the NiFe layer can be determined by changing the magnitude of the synchronous magnetic field, so as to define the write signals "0" and "1", and if the vortex rotation direction of the NiFe layer is the same as that of the CoFe layer, the signal is "1", otherwise, the signal is 0. Example fig. 6b is a signal sensing circuit that reads a signal by applying a sensing voltage to a bit line after the signal is written to a composite magnetic nanoring cell memory cell, while applying a select voltage to a word line, at which time the access transistor channel is turned on so that current flow through the bit line is detected by the sense amplifier. In this case, when the rotation directions of the NiFe layer vortex state and the CoFe layer vortex state are opposite to each other and are high resistance state, and vice versa, the rotation directions of the NiFe layer vortex state and the CoFe layer vortex state are consistent to be low resistance state, the record of one byte is determined by the detected current value. Compared with the prior art, when the device is used as a magnetic random access memory, the reading and writing can be realized by adding a very low switching field (relative to a single-layer magnetic nanoring), and in addition, when the device is used as a magnetic random access memory, the coding codes of the device can be compiled more and can be selected into a vortex state and a left onion state, and the left onion state and an inverted onion state are marked as compiled codes '0' and '1'. Furthermore, the inventive device provides a large range for realizing the tilt magnetic anisotropy due to the exchange elastic coupling effect of the interface. For example, in the device II of the present invention, when θ is 0 ° and θ is 90 °, the range of the modulation of the inversion field is large, so that the write field can be flexibly selected according to actual requirements.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art, after learning the present disclosure, can make several equivalent changes and substitutions without departing from the principle of the present invention, and these equivalent changes and substitutions should also be considered as belonging to the protection scope of the present invention.

Claims

1. The composite multilayer magnetic nanoring array memory device is characterized in that: the structure is a double-layer rectangular nanoring array, and the double-layer rectangular nanoring array comprises a multi-layer magnetic material with vertical anisotropy as a lower layer material and a soft magnetic material with in-plane anisotropy as an upper layer material; the lower layer material is directly attached to the substrate, and the upper layer material grows on the lower layer material; the upper layer rectangular nanoring array structure formed by the upper layer material and the lower layer rectangular nanoring array structure formed by the lower layer material are concentric equal-size rectangular nanoring arrays;

2. The composite multilayer magnetic nanoring array memory device of claim 1, wherein: s ∈ (w, 1200 nm).

3. The method for manufacturing the composite multilayer magnetic nanoring array memory device according to claim 1 or 2, wherein: the method comprises the following steps of forming a required template on a material of a substrate, firstly depositing a hard magnetic material with vertical anisotropy on the template to form a lower rectangular nanoring array, then depositing a soft magnetic material with in-plane anisotropy on the template to form an upper rectangular nanoring array, and directly coupling the upper and lower layers of magnetic materials together through an interface.

4. The method of fabricating a composite multilayer magnetic nanoring array memory device according to claim 3, wherein: the method for preparing the template on the substrate is one of a deep ultraviolet lithography technology, an electron beam exposure technology and a nano-imprinting technology; the method for forming the nano-ring array by deposition on the template is one of a magnetron sputtering technology, an electron beam evaporation technology and a pulse laser deposition technology.

5. The method of fabricating a composite multilayer magnetic nanoring array memory device according to claim 3, wherein: the substrate is made of any one of a silicon wafer, a silicon oxide wafer, an ITO glass substrate, an FTO glass substrate, a K9 glass substrate, a quartz glass substrate, a sapphire single crystal wafer and a gallium arsenide substrate.

6. The method for preparing a composite multilayer magnetic nanoring array memory device according to any one of claims 3 to 5, wherein: the lower layer material is vertically anisotropic (Co/Pd)_nMultilayer film, (Co/Pt)_nOne of the multilayer film, FeCo/Pt multilayer film, FePt alloy and CoPt alloy, and its perpendicular anisotropy constant K_u∈(5×10⁶erg/cm³,6×10⁷erg/cm³) (ii) a The upper layer material is a soft magnetic material, which is a magnetic material with low coercive force and high magnetic permeability.

7. The method of fabricating a composite multilayer magnetic nanoring array memory device of claim 6, wherein: the upper layer is of a single-layer film structure formed by one of NiFe, CoFe, CoFeB, Fe, Co and Ni or an alloy or multi-layer film structure formed by multiple materials.

8. The use of the composite multilayer magnetic nanoring array memory device of claim 1 or 2, wherein: the method is used for preparing a magnetic random access memory, a magnetic nano-switch device, a magnetic spin device and a magnetic sensor.