CN109192232B - Magnetic storage device based on separation magnetic tunnel junction and probe magnetic read write head - Google Patents
Magnetic storage device based on separation magnetic tunnel junction and probe magnetic read write head Download PDFInfo
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- CN109192232B CN109192232B CN201810750103.8A CN201810750103A CN109192232B CN 109192232 B CN109192232 B CN 109192232B CN 201810750103 A CN201810750103 A CN 201810750103A CN 109192232 B CN109192232 B CN 109192232B
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- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
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- G11C—STATIC STORES
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- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
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Abstract
The invention discloses a magnetic storage device based on a separated magnetic tunnel junction and a probe magnetic read-write head, wherein the magnetic read-write head and a storage medium of the magnetic storage device are separated from each other; the magnetic read-write head is a probe structure; the fixed layer of the separated magnetic tunnel junction is positioned at the tip of the magnetic read-write head, the free layer of the separated magnetic tunnel junction is positioned on the surface of the storage medium, and the tunneling layer of the separated magnetic tunnel junction is positioned on at least one of the surface of the fixed layer and the surface of the free layer. The invention separates the free layer and the fixed layer in the magnetic tunnel junction, manufactures the fixed layer on the magnetic read-write head of the nano-grade probe structure, manufactures the free layer on the storage medium, and respectively serves as read-write and data storage functions, thereby reducing the process difficulty and the cost, simplifying the structure of the magnetic read-write head, realizing the read-write integration, and realizing the high-density storage by reducing the size of the magnetic read-write head.
Description
Technical Field
The invention belongs to the technical field of information storage, and particularly relates to a magnetic storage device based on a separated magnetic tunnel junction and a probe magnetic read-write head.
Background
In the traditional memory, a Static Random Access Memory (SRAM) and a Dynamic Random Access Memory (DRAM) belong to volatile memories, and need to be refreshed and powered up continuously in the working process, so that the problem of very serious energy consumption is faced; NAND FLASH can only be used for peripheral storage of computer and other devices due to its slow speed, and has insufficient service life, resistance to scratch, stability and radiation resistance, and is difficult to meet the requirements of spaceflight and military industry. Among the new memories, there is a spin torque transfer-Magnetic random access memory (STT), and the core memory structure is a Magnetic Tunnel Junction (MTJ), which has very significant performance advantages: the speed is high, and is equivalent to DRAM, which is about 10 ten thousand times of NAND FLASH; the data are not lost after power failure; read-write without continuous refreshThe current is small, and the power consumption is far lower than that of a DRAM and an SRAM; has very good erasing and writing resistance up to 1010Above, meaning that it has a long service life; data is stored by means of a magnetic layer, which is considered to have radiation-resistant properties; the method is better compatible with a semiconductor process. STT-MRAM is currently mainly subject to two constraints, one is that the manufacturing process is very demanding and complicated, resulting in high manufacturing cost, and the sputtering of the multi-layer film structure and the large amount of photolithography required for manufacturing the tiny memory cells are the main reasons for high cost; secondly, when the size is smaller and the core structure MTJ enters a sub-20 nm size, the magnetic layer for storing data faces a more serious thermal disturbance problem, so that the data cannot maintain sufficient stability, and meanwhile, the 1T-1MTJ structure of the current STT-MRAM cannot have a high storage density due to a large transistor, so that the storage density is further increased, and the sizes of the transistor and the whole memory can be reduced by driving the reduction of read-write current from the reduction of the MTJ size. Therefore, in order to further advance the development of such memories, the manufacturing process is simplified and the size of MTJ is further reduced.
In the fields of cloud storage and cloud technology, big data analysis, monitoring systems, enterprise data storage and the like, a large number of mechanical hard disks which are comprehensively superior in capacity, price, performance and stability are used instead of solid state disks or other high-speed memories. In combination with the technical development of the last decade, the capacity of a mechanical hard disk is increasing, but the capacity is increasing relatively slowly, and the increasing demand of people for information capacity cannot be kept up to date. In addition, like the thermally assisted magnetic recording technology, which requires a near-field heating laser to be added to the magnetic head, the dot matrix patterning technology is heavily used in ultra-high precision photolithography and etching processes, which increases the complexity of the hard disk structure and manufacture and increases the manufacturing cost of the hard disk. Furthermore, the current mechanical hard disk has the problem of single technology of magnetic recording head, and the technology of the current technology is more to make the single recording unit of the magnetic recording medium smaller, but the magnetic recording head is difficult to improve.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to solve the technical problems of complex process, high cost and low storage density of the magnetic storage device in the prior art.
In order to achieve the above object, an embodiment of the present invention provides a magnetic storage device based on a separated magnetic tunnel junction and a probe magnetic read/write head, wherein the magnetic read/write head and a storage medium of the magnetic storage device are separated from each other; the magnetic read-write head is of a probe structure; the fixed layer of the separated magnetic tunnel junction is positioned at the tip of the magnetic read-write head, the free layer of the separated magnetic tunnel junction is positioned on the surface of the storage medium, and the tunneling layer of the separated magnetic tunnel junction is positioned on at least one of the surface of the fixed layer and the surface of the free layer.
Specifically, the magnetic read write head comprises a substrate layer and a tip, wherein the tip comprises a pinning layer and a fixed layer, and the magnetic read write head is integrated with reading and writing.
Specifically, the magnetic storage device includes a self-assembled isolated memory and a hard disk.
Specifically, the magnetic storage device is a self-assembled isolated memory, and the storage medium adopts a self-assembled isolated thin film technology.
Specifically, the storage medium is a planar thin film structure and comprises a substrate layer, an isolation layer and a free layer;
the substrate layer plays a role in conducting electricity and supporting a main body, the isolation layer is made of non-ferromagnetic materials and plays an isolation role, and the free layer is a ferromagnetic cylinder and is isolated by the isolation layer;
each ferromagnetic pillar represents a memory cell whose magnetization state represents stored data.
Specifically, the magnetic storage device is a hard disk, the storage medium is a hard disk surface and comprises a base layer and a free layer, the base layer plays a role in electric conduction and main body support, and the free layer is a magnetic layer grown on the hard disk surface.
Specifically, the magnetic storage device forms a complete magnetic tunnel junction through point contact of a magnetic read/write head and a storage medium and conducts current, realizes write operation by using a spin transfer torque effect, and realizes read operation by using a tunneling magnetoresistance effect.
Specifically, the writing operation and the data writing operation by using the spin transfer torque effect specifically include:
applying a large voltage between the magnetic read/write head and the storage medium, and according to the spin transfer torque effect, the current carrying spin torque rewrites the magnetization direction of the free layer, and if the aim is to make the magnetization directions of the free layer and the fixed layer the same, the current is applied in the direction from the free layer to the fixed layer, namely from the storage medium to the magnetic read/write head; if the goal is to magnetize the free layer and the fixed layer in opposite directions and the direction of current application should be from the fixed layer to the free layer, i.e., from the magnetic read/write head to the storage medium, a 0 or 1 can be written by controlling the direction of current flow.
Specifically, the implementation of the read operation by using the tunneling magnetoresistance effect specifically includes:
applying a small voltage between the magnetic read/write head and the storage medium, and determining a low resistance state if the magnetization direction of the free layer is the same as the magnetization direction of the fixed layer according to the tunneling magnetoresistance effect; if the magnetization direction of the free layer is opposite to that of the fixed layer, the resistance state is high, the magnetization direction of the free layer represents stored data, and whether the stored data is 0 or 1 can be judged according to the resistance.
Specifically, the base layer material is a conductive semiconductor material or a conductive metal material; the pinning layer is a ferromagnetic layer/antiferromagnetic layer structure or an antiferromagnetic layer/nonmagnetic metal layer structure, the ferromagnetic layer is made of CoMnSi, CoFeSi, CoCr, FeNi, FeCo, Fe, Co and Ni, the antiferromagnetic material is FeMn, IrMn, CoO and NiO, and the nonmagnetic metal material is Cu, Au, Pt, Ta or Ru; the material of the fixed layer is CoFeB, CoMnSi, CoFeSi, CoFeAl, GaMnAs, CoFeAlSi, CoFe, FePt, CoPt, FeNi, Fe, Co and Ni; the tunneling layer is made of MgO and Al2O3、AlOx、TiO2、HfO2、MgAlO4AlN, BN; the material of the free layer is CoFeB, CoMnSi, CoFeSi, CoFeAl, GaMnAs, CoFeAlSi, CoFe, FePt, CoPt, FeNi, Fe, Co and Ni; the material of the isolating layer is ZrO2、MgO。
Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:
(1) the invention separates the magnetic free layer and the fixed layer in the MTJ, manufactures the fixed layer on the very tiny structure of the tip of the magnetic read/write head of the memory, manufactures the free layer on the storage medium, and respectively serves as the read/write and data storage functions, thereby reducing the process difficulty and the cost;
(2) the invention simplifies the structure of the magnetic read-write head through the magnetic read-write head with the nano-grade probe structure, realizes the read-write integration, and realizes the high-density storage by reducing the size of the magnetic read-write head;
(3) the invention uses the self-assembly isolation film as the storage medium to manufacture the very dense nano-scale micro-magnetic column storage array and realize high density; the manufacturing process is simple, and the cost is reduced; better magnetic anisotropy is realized by utilizing the shape anisotropy of the isolated columnar magnetic material, so that better stability can be kept when the size of the storage unit is reduced;
(4) the invention forms a complete MTJ structure through point contact of the magnetic read-write head and the storage medium and conducts current, realizes the data read-write function as STT-MRAM by means of STT effect and TMR effect, not only maintains the advantages of STT-MRAM, but also solves the main two problems faced by STT-MRAM, realizes the purposes of reducing cost and size, and simultaneously reduces the size and power consumption.
Drawings
FIG. 1 is a schematic diagram of a prior art MTJ structure.
FIG. 2 is a schematic diagram of a high-density self-assembled isolated memory structure based on a split magnetic tunnel junction and a probe magnetic read/write head according to an embodiment of the present invention.
FIG. 3(a) is a schematic diagram of a first magnetic read/write head and storage medium structure of a self-assembled isolated memory.
FIG. 3(b) is a schematic diagram of a second magnetic read/write head and storage medium structure of a self-assembled isolated memory.
FIG. 3(c) is a schematic diagram of a third magnetic read/write head and storage medium structure of a self-assembled isolated memory.
FIG. 4 is a schematic diagram of a high density mechanical hard disk based on a split magnetic tunnel junction and probe magnetic read/write head according to an embodiment of the present invention.
FIG. 5(a) is a schematic diagram of a first type of magnetic read/write head and storage medium structure for a mechanical hard disk.
FIG. 5(b) is a schematic diagram of a second type of magnetic read/write head and storage medium structure for a mechanical hard disk.
FIG. 5(c) is a schematic diagram of a third type of magnetic read/write head and storage medium structure for a mechanical hard disk.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
FIG. 1 is a schematic diagram of a prior art MTJ structure. As shown in fig. 1, a magnetic layer whose magnetization direction is fixed is referred to as a fixed layer; a magnetic layer whose magnetization direction is changeable, called a free layer; and a layer of insulating material, called tunneling layer, sandwiched between the two layers.
The Spin Torque Transfer (STT) effect means that in a classical MTJ structure composed of a pinned layer/a tunneling layer/a free layer, if electrons flow from the pinned layer to the free layer through the tunneling layer, the electrons are first polarized in such a way that the spin direction is the same as the magnetization direction of the pinned layer, and then the polarized state is transferred to the free layer so that the magnetization directions of the pinned layer and the free layer are the same, so that the magnetization directions of the pinned layer and the free layer become parallel; if the electrons flow from the free layer to the pinned layer, electrons having a spin direction opposite to the magnetization direction of the pinned layer are reflected by the pinned layer back to the free layer, which transfers the opposite polarization state to the free layer, causing the magnetization direction of the pinned layer free layer to be opposite.
The tunneling Magneto-resistance (TMR) effect means that when electrons are transferred between a free layer and a pinned layer, if the magnetization directions of the two layers are parallel, the electrons are transferred from one layer to the other layer and are scattered little by the layer with the same magnetization direction, so that the current is large, and the state is low resistance, whereas if the magnetization directions of the two layers are anti-parallel, the electrons are transferred from one layer to the other layer and are scattered much by the layer with the opposite magnetization direction, so that the current is small, and the state is high resistance.
By STT effect, the magnetization direction of the free layer can be artificially controlled and changed to be parallel or antiparallel to the fixed layer by changing the current direction flowing through the MTJ; from the TMR effect, the relative magnetization states of the free and fixed layers can be known by reading the resistance value of the MTJ. Thus, the magnetization direction of the free layer can be read or changed only electrically, and can be maintained non-volatile even when not powered, and if the magnetization direction represents stored data, the MTJ can be used to implement the function of a non-volatile memory.
FIG. 2 is a schematic diagram of a high-density self-assembled isolated memory structure based on a split magnetic tunnel junction and a probe magnetic read/write head according to an embodiment of the present invention. As shown in fig. 2, the memory includes a magnetic read write head and a storage medium separated from each other, wherein the magnetic read write head is a probe structure, and a pinned layer of MTJ is located at a tip; the storage medium is a plane film structure, and the free layer of the MTJ is the surface of the plane film structure; the tunneling layer of the MTJ is located on at least one of a surface of the fixed layer of the magnetic read/write head and a surface of the free layer of the storage medium.
The magnetic read-write head and the storage medium are mutually separated, and are combined through point contact when reading and writing are needed to be carried out, so that a complete MTJ structure is combined, and then the read-write is carried out in a pure electric mode like an STT-MRAM, so that a storage function is realized.
FIG. 3(a) is a schematic diagram of a first magnetic read/write head and storage medium structure of a self-assembled isolated memory. As shown in FIG. 3(a), the tunneling layer of the MTJ is located in the magnetic read/write head. A magnetic read/write head includes a base layer and a tip having a magnetic multilayer film structure on a nanometer scale. The structure of the tip of the magnetic read-write head is a pinning layer, a fixed layer and a tunneling layer from top to bottom along the direction of the needle tip. The storage medium includes a land layer, a separation medium, and a free layer.
FIG. 3(b) is a schematic diagram of a second magnetic read/write head and storage medium structure of a self-assembled isolated memory. As shown in FIG. 3(b), the tunneling layer of the MTJ resides on the storage medium. A magnetic read/write head includes a base layer and a tip having a magnetic multilayer film structure on a nanometer scale. The structure of the tip of the magnetic read write head is a pinning layer and a fixed layer from top to bottom along the direction of the tip. The storage medium includes a land layer, a separation medium, a free layer, and a tunneling layer.
FIG. 3(c) is a schematic diagram of a third magnetic read/write head and storage medium structure of a self-assembled isolated memory. As shown in FIG. 3(c), the tunneling layer of the MTJ is located in the magnetic read/write head and the storage medium. A magnetic read/write head includes a base layer and a tip having a magnetic multilayer film structure on a nanometer scale. The structure of the tip of the magnetic read/write head is a pinning layer, a fixed layer, and a tunneling layer from top to bottom along the direction of the tip. The storage medium includes a land layer, a separation medium, a free layer, and a tunneling layer.
In fig. 3, the base layer plays a role of electric conduction and body support, and may be a conductive semiconductor material such as silicon, germanium, or other metal material. The pinned layer is used to keep the magnetization direction of the fixed layer unchanged, and is generally a ferromagnetic layer/antiferromagnetic layer structure or an antiferromagnetic layer/nonmagnetic metal layer structure or an alternating Co/Ni and Co/Fe multilayer film structure, where the ferromagnetic layer may be a ferromagnetic metal or ferromagnetic alloy such as CoMnSi, CoFeSi, CoCr, FeNi, FeCo, Fe, Co, Ni, etc., the antiferromagnetic material may be a material such as FeMn, IrMn, CoO, NiO, etc., and the nonmagnetic metal may be a material such as Cu, Au, Pt, Ta, Ru, etc. The pinned layer has a fixed magnetization direction, generally functions to generate and detect spin current, and may be a ferromagnetic metal or a ferromagnetic alloy such as CoFeB, CoMnSi, CoFeSi, CoFeAl, GaMnAs, CoFeAlSi, CoFe, FePt, CoPt, FeNi, Fe, Co, Ni, or the like. The tunneling layer can be MgO or Al2O3、AlOx、TiO2、HfO2、MgAlO4AlN and BN, and the like, and separates the fixed layer from the free layer to form an electron tunneling barrier. The free layer is a ferromagnetic cylinder, which can be CoFeB, CoMnSi, CoFeSi, CoFeAl, GaMnAs, CoFeAlSi, CoFe, FePt, CoPt, FeNi, Fe, Co, Ni, or other ferromagnetic metal or ferromagnetic alloy, and is separated by a separating medium, which is ZrO2Non-magnetic materials such as MgO, for example, for isolation. The free layer is a ferromagnetic cylinder separated by an isolation layer. Each ferromagnetic pillar represents a memory cell whose magnetization state represents stored data. The fixed layer, the tunneling layer and the free layer jointly form a core structure of the MTJ, data are stored on the free layer, and the TMR effect and the STT effect can be generated by combining the fixed layer and the tunneling layer, so that the function of reading the data and writing the data in a pure electric mode is realized.
The magnetic read-write head is characterized in that a composite multilayer film structure is firstly grown on a conductive columnar substrate layer through thin film growth processes such as sputtering, deposition and the like, and then one end of a column body is etched into a very thin needle point structure through a Focused Ion Beam (FIB) or other methods, so that the diameter can reach the order of magnitude of sub 10 nm.
The storage medium adopts the technology of self-assembly isolation type thin films, data are stored on the thin films formed by ferromagnetic materials and non-ferromagnetic materials, wherein the ferromagnetic materials form a columnar structure in the thin films and are isolated by the non-ferromagnetic materials, the isolated small columnar magnetic bodies have respective magnetization directions and are used as free layers to be in contact with a magnetic reading and writing head for reading and writing to form independent storage units, the small columnar magnetic bodies can reach a small size to reach a sub-5 nm size, and good magnetic stability can be kept by means of high shape anisotropy.
When the magnetic read write head is in contact with the storage medium, the fixed layer on the magnetic read write head, the free layer formed by the magnetic unit on the storage medium and the middle insulating layer form an MTJ structure, and current can flow between the magnetic read write head and the storage medium through the insulating layer by tunneling effect.
Based on the principle of storing data in the magnetic tunnel junction, a complete MTJ cell is formed when the magnetic read/write head is in contact with the dielectric material of the memory cell. Wherein the magnetic read/write head portion acts as a fixed layer and the memory cell acts as a free layer. The magnetization direction of the magnetic material in a memory cell can be changed according to the direction of the current. After a write operation is completed, the information is stored in the cell in a nonvolatile manner. And moving the magnetic read-write head to the position of other storage units for the next write operation. If the data writing operation is carried out, a large voltage is applied between the magnetic reading and writing head and the storage medium, the current carries spin torque to rewrite the magnetization direction of the free layer according to the STT effect, and if the magnetization directions of the free layer and the fixed layer are the same, the current is applied from the free layer to the fixed layer, namely from the storage medium to the magnetic reading and writing head; if the goal is to magnetize the free layer and the fixed layer in opposite directions and the direction of current application should be from the fixed layer to the free layer, i.e., from the magnetic read/write head to the storage medium, a 0 or 1 can be written by controlling the direction of current flow.
Similarly, information stored in a certain cell is read based on the TMR effect, and when the magnetic read/write head makes a point contact with the memory cell, the resistance state of the MTJ in that state is measured, thereby obtaining the information stored in the cell. In actual operation, firstly, the magnetic read-write head is in point contact with a region where a certain storage unit (small magnetic column) is located on a storage medium, if data reading operation is carried out, a small voltage is applied between the magnetic read-write head and the storage medium, and according to TMR effect, if the magnetization direction of a free layer in the region is the same as that of a fixed layer, the free layer is in a low-resistance state; if the magnetization direction of the free layer is opposite to that of the pinned layer in this region, then it is in a high resistance state. The magnetization direction of the free layer indicates stored data, and whether the stored data is 0 or 1 can be determined from the magnitude of the resistance.
FIG. 4 is a schematic diagram of a high density mechanical hard disk based on a split magnetic tunnel junction and probe magnetic read/write head according to an embodiment of the present invention. As shown in fig. 4, the mechanical hard disk includes a magnetic read write head and a storage medium separated from each other, wherein the magnetic read write head is a probe structure, and a pinned layer of MTJ is located at a tip; the storage medium is a multilayer thin film structure, and the free layer of the MTJ is a magnetic layer on the surface of the disk surface; the tunneling layer of the MTJ is located on at least one of a surface of the fixed layer of the magnetic read/write head and a surface of the free layer of the storage medium.
FIG. 5(a) is a schematic diagram of a first type of magnetic read/write head and storage medium structure for a mechanical hard disk. As shown in FIG. 5(a), the tunneling layer of the MTJ is located in the magnetic read/write head. A magnetic read/write head includes a base layer and a tip having a magnetic multilayer film structure on a nanometer scale. The structure of the tip of the magnetic read-write head is a pinning layer, a fixed layer and a tunneling layer from top to bottom along the direction of the needle tip. The storage medium is also a multilayer thin film structure composed of a plurality of materials and comprises a base layer and a free layer from bottom to top.
FIG. 5(b) is a schematic diagram of a second type of magnetic read/write head and storage medium structure for a mechanical hard disk. As shown in FIG. 5(b), the tunneling layer of the MTJ is located on the storage medium. A magnetic read/write head includes a base layer and a tip having a magnetic multilayer film structure on a nanometer scale. The structure of the tip of the magnetic read/write head is a pinning layer and a fixed layer from top to bottom along the direction of the needle tip. The storage medium is also a multilayer thin film structure composed of a plurality of materials and comprises a base layer, a free layer and a tunneling layer from bottom to top.
FIG. 5(c) is a schematic diagram of a third type of magnetic read/write head and storage medium structure for a mechanical hard disk. As shown in FIG. 5(c), the tunneling layer of the MTJ is located in the magnetic read/write head and the storage medium. A magnetic read/write head includes a base layer and a tip having a magnetic multilayer film structure on a nanometer scale. The structure of the tip of the magnetic read-write head is a pinning layer, a fixed layer and a tunneling layer from top to bottom along the direction of the needle tip. The storage medium is also a multilayer thin film structure composed of a plurality of materials and comprises a base layer, a free layer and a tunneling layer from bottom to top.
In fig. 5, the base layer serves as a conductive and body supporting member, and may be a conductive semiconductor material such as silicon or germanium, or may be another metal material. The pinned layer is used to keep the magnetization direction of the fixed layer unchanged, and is generally a ferromagnetic layer/antiferromagnetic layer structure or an antiferromagnetic layer/nonmagnetic metal layer structure or an alternating Co/Ni and Co/Fe multilayer film structure, where the ferromagnetic layer may be a ferromagnetic metal or ferromagnetic alloy such as CoMnSi, CoFeSi, CoCr, FeNi, FeCo, Fe, Co, Ni, etc., the antiferromagnetic material may be a material such as FeMn, IrMn, CoO, NiO, etc., and the nonmagnetic metal may be a material such as Cu, Au, Pt, Ta, Ru, etc. The pinned layer has a fixed magnetization direction, generally functions to generate and detect spin current, and may be a ferromagnetic metal or a ferromagnetic alloy such as CoFeB, CoMnSi, CoFeSi, CoFeAl, GaMnAs, CoFeAlSi, CoFe, FePt, CoPt, FeNi, Fe, Co, Ni, or the like. The tunneling layer can be MgO or Al2O3、AlOx、TiO2、HfO2、MgAlO4AlN and BN, and the like, and separates the fixed layer from the free layer to form an electron tunneling barrier. The free layer is a ferromagnetic cylinder, which can be CoFeB, CoMnSi, CoFeSi, CoFeAl, GaMnAs, CoFeAlSi, CoFe, FePt, CoPt, FeNi, Fe, Co, Ni, or other ferromagnetic metal or ferromagnetic alloy, and is separated by a separating medium, which is ZrO2And a nonmagnetic material such as MgO. Each ferromagnetic pillar represents a memory cell whose magnetization state represents stored data. The fixed layer, the tunneling layer and the free layer jointly form a core structure of the MTJ, data are stored on the free layer, and the TMR effect and the STT effect can be generated by combining the fixed layer and the tunneling layer, so that the function of reading the data and writing the data in a pure electric mode is realized.
In operation, the magnetic read/write head and the storage medium are controlled by the control structure to be brought into contact at different locations. When the magnetic read write head contacts the disk surface, a tunneling current is transmitted to a certain small specific area, and when the current is large, the tunneling current transmits a magnetic moment to a free layer of the area according to the STT effect, so that the magnetization direction of the free layer can be changed, and the change is controlled by the current direction, thereby realizing the data write operation; their magnetization direction is maintained after the current is removed to store data; if the current is small, it is not sufficient to change the magnetization direction of the free layer, but its resistance state can be measured, by which the magnetization direction of the free layer can be reflected according to the TMR effect, thereby reading the stored data. The tiny areas form storage units, and data can be stored in a nonvolatile mode, so that the contact type nonvolatile hard disk storage is formed.
The storage medium has a continuous magnetic film for data storage, and the magnetic read/write head is responsible for data reading and writing and is in contact with the storage medium. The magnetic read write head in the structure of the invention is similar to a probe in shape, direct point contact with the disk surface is required to be kept during reading and writing, current is transmitted from the magnetic read write head to the disk surface, and the reading and writing functions are realized by depending on the transmission of the current.
The magnetic read-write head is characterized in that a composite multilayer film structure is firstly grown on a conductive columnar substrate through thin film growth processes such as sputtering, deposition and the like, and then one end of a column body is etched into a very thin needle point structure through a Focused Ion Beam (FIB) or other methods, so that the diameter can reach the order of magnitude of sub 10 nm.
The hard disk storage medium is a multilayer continuous film grown by a film growth process such as sputtering, deposition and the like.
It should be noted that some of the materials of the magnetic read/write head and the storage medium given above have only a reference role, and the MTJ here is not concerned with and should cover all kinds, including different kinds of MTJ of various materials, various structures.
The above description is only for the preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. A magnetic storage device based on a split magnetic tunnel junction and probe magnetic read/write head,
the magnetic read write head and the storage medium of the magnetic storage device are separated from each other;
the magnetic read-write head is of a probe structure;
the fixed layer of the separated magnetic tunnel junction is positioned at the tip of the magnetic read-write head, the free layer of the separated magnetic tunnel junction is positioned on the surface of the storage medium, and the tunneling layer of the separated magnetic tunnel junction is positioned on at least one of the surface of the fixed layer and the surface of the free layer.
2. The magnetic storage device of claim 1 wherein the magnetic read write head includes a base layer and a tip, the tip including a pinning layer and a fixed layer, the magnetic read write head being read-write integrated.
3. The magnetic storage device according to claim 1 or 2, wherein the magnetic storage device comprises a self-assembled isolated memory and a hard disk.
4. The magnetic memory device of claim 3, wherein the magnetic memory device is a self-assembled isolated memory, and the storage medium is a self-assembled isolated thin film technology.
5. The magnetic memory device of claim 4 wherein the storage medium is a planar thin film structure comprising a base layer, an isolation layer, and a free layer;
the substrate layer plays a role in conducting electricity and supporting a main body, the isolation layer is made of non-ferromagnetic materials and plays an isolation role, and the free layer is a ferromagnetic cylinder and is isolated by the isolation layer;
each ferromagnetic pillar represents a memory cell whose magnetization state represents stored data.
6. The magnetic storage device of claim 3, wherein the magnetic storage device is a hard disk and the storage medium is a hard disk surface, comprising a base layer and a free layer, the base layer serving as a conductive and body supporting layer, the free layer being a magnetic layer grown on the hard disk surface.
7. The magnetic memory device according to claim 1 or 2, wherein the magnetic memory device forms a complete magnetic tunnel junction by point contact of the magnetic read/write head and the storage medium and conducts current, and performs a write operation using a spin transfer torque effect and a read operation using a tunneling magnetoresistance effect.
8. The magnetic memory device of claim 7, wherein the writing data operation using spin transfer torque effect includes:
applying a large voltage between the magnetic read/write head and the storage medium, and according to the spin transfer torque effect, the current carrying spin torque rewrites the magnetization direction of the free layer, and if the aim is to make the magnetization directions of the free layer and the fixed layer the same, the current is applied in the direction from the free layer to the fixed layer, namely from the storage medium to the magnetic read/write head; if the goal is to magnetize the free layer and the fixed layer in opposite directions and the direction of current application should be from the fixed layer to the free layer, i.e., from the magnetic read/write head to the storage medium, a 0 or 1 can be written by controlling the direction of current flow.
9. The magnetic memory device according to claim 7, wherein the reading operation is implemented by using a tunneling magnetoresistance effect, and specifically comprises:
applying a small voltage between the magnetic read/write head and the storage medium, and determining a low resistance state if the magnetization direction of the free layer is the same as the magnetization direction of the fixed layer according to the tunneling magnetoresistance effect; if the magnetization direction of the free layer is opposite to that of the fixed layer, the resistance state is high, the magnetization direction of the free layer represents stored data, and whether the stored data is 0 or 1 can be judged according to the resistance.
10. The magnetic memory device of claim 4, wherein the substrate layer material is a conductive semiconductor material or a conductive metal material; the pinning layer is a ferromagnetic layer/antiferromagnetic layer structure or an antiferromagnetic layer/nonmagnetic metal layer structure, the ferromagnetic layer is made of CoMnSi, CoFeSi, CoCr, FeNi, FeCo, Fe, Co, Ni, the antiferromagnetic material is FeMn, IrMn, CoO, NiO, and the nonmagnetic metal material is Cu, Au, Pt, Ta, Ru; the material of the fixed layer is CoFeB, CoMnSi, CoFeSi, CoFeAl, GaMnAs, CoFeAlSi, CoFe, FePt, CoPt, FeNi, Fe, Co and Ni; the tunneling layer is made of MgO and Al2O3、AlOx、TiO2、HfO2、MgAlO4AlN, BN; the material of the free layer is CoFeB, CoMnSi, CoFeSi, CoFeAl, GaMnAs, CoFeAlSi, CoFe, FePt, CoPt, FeNi, Fe, Co and Ni; the material of the isolating layer is ZrO2、MgO。
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