Magnetic superconducting memory and preparation method, reading and writing method thereof

Abstract

The application provides a magnetic superconducting memory and a preparation method and a read-write method thereof.The magnetic superconducting memory of the application uses the resistance difference between superconducting states and normal states to map the magnetization state; the ferromagnetic layer is used as an adjustable free layer, and the magnetization direction of the ferromagnetic layer affects the size of the superconducting critical current of the superconducting layer; the heavy metal layer generates a spin-orbit torque through the spin Hall effect to drive the magnetization of the ferromagnetic layer to flip; the application realizes an infinite on-off ratio between superconducting states and normal states through the superconducting diode magnetoresistance effect, and realizes a high-efficiency and high-reliability nonvolatile storage scheme by combining the current-driven spin-orbit torque magnetization flipping technology, which completely overcomes the inherent defects of the traditional TMR and significantly improves the signal contrast of the storage unit; the heterostructure designed in the application replaces the traditional magnetic tunnel junction, reduces the material stacking and process complexity, and uses materials compatible with the CMOS process to promote the large-scale integration of low-temperature memories.

Description

Technical Field

[0001] This invention relates to the field of memory technology, and in particular to a magnetic superconducting memory and its preparation and reading / writing methods. Background Technology

[0002] Magnetic Random Access Memory (MRAM), as an emerging non-volatile memory technology, relies on the manipulation and retrieval of magnetization states. Traditional MRAM employs a magnetic tunnel junction (MTJ) structure, achieving magnetization state retrieval through the tunneling magnetoresistance (TMR) effect. A typical MTJ consists of an ultrathin insulating layer (such as MgO) sandwiched between a ferromagnetic free layer and a fixed layer (such as CoFeB). Its resistance depends on the relative direction of magnetization of the free and fixed layers (parallel or antiparallel). When the magnetization directions are parallel, it exhibits low resistance ("0" state), and when they are antiparallel, it exhibits high resistance ("1" state). However, this technology has the following significant drawbacks: 1. Low on / off ratio limits performance. The on / off ratio of TMR (i.e., the ratio of the resistance of the high-resistance state to the low-resistance state) is typically less than 10, resulting in insufficient signal discrimination. This necessitates complex external circuitry for signal amplification, increasing power consumption and design complexity. Furthermore, a low on / off ratio easily leads to readout errors, especially with a significant decrease in reliability under high temperature or high noise environments; 2. High material and process complexity: the fabrication of MTJs requires precise stacking of multiple heterogeneous materials (such as CoFeB / MgO / CoFeB), and is extremely sensitive to the thickness of the insulating layer and the interface quality. Such processes have poor compatibility with existing CMOS technologies, leading to increased manufacturing costs and challenges for large-scale production; 3. Limitations of the approach: In recent years, researchers have attempted to read the magnetization state by combining superconducting and ferromagnetic materials (such as FM / SC / FM spin valves), using changes in the superconducting critical temperature (Tc) to reflect the magnetization direction. However, the variation in Tc in such methods is extremely small (typically on the order of millikelvin), requiring operation within an extremely narrow temperature window, thus limiting their practical value.

[0003] Given that current MRAMs employ a magnetic tunnel junction structure, which suffers from a low on / off ratio due to the tunneling magnetoresistance effect (TMR), making signal identification difficult, it is necessary to improve this aspect. Summary of the Invention

[0004] To address the problems of low on / off ratio due to tunneling magnetoresistance (TMR) in MRAM, leading to difficulties in signal recognition, high process complexity, and insufficient reliability, this invention proposes a magnetic superconducting memory and its fabrication and read / write methods. By utilizing the superconducting diode magnetoresistance effect (SDMR), an infinite on / off ratio between the superconducting and normal states is achieved, significantly improving the signal contrast of the memory cell. A heterostructure of SC / FM / HM (superconducting layer / ferromagnetic layer / heavy metal layer) is designed to replace the traditional magnetic tunnel junction (MTJ), reducing material stacking and process complexity. Materials compatible with CMOS processes (such as Nb, Co, and Pt) are used to promote the large-scale integration of low-temperature memories. Combining the stable magnetization characteristics of the perpendicular magnetic anisotropy (PMA) ferromagnetic layer with the low power consumption characteristics of the superconducting state, a high-performance, long-lifetime memory cell is constructed.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a magnetic superconducting memory, comprising:

[0007] Substrate;

[0008] A heavy metal layer is located on the surface of the substrate;

[0009] A ferromagnetic layer is located away from the substrate surface of the heavy metal layer;

[0010] A superconducting layer is located on the ferromagnetic layer away from the substrate surface;

[0011] The heavy metal layer generates a spin orbital torque through the spin Hall effect, driving the reversible switching of the magnetization direction of the ferromagnetic layer.

[0012] Preferably, the material of the heavy metal layer includes at least one of Pt, Ta, Mo, Ru, Ir, Pd and their alloys.

[0013] Preferably, the material of the superconducting layer includes at least one of Nb, NbTi, Nb3Sn, Al, Pb, V3Ga and their alloys.

[0014] Preferably, the material of the ferromagnetic layer includes at least one of Fe, Co, Ni, NiFe alloy, CoFeB, CoPt alloy, and FePt alloy.

[0015] Preferably, the substrate includes any one of a silicon substrate, a sapphire substrate, and a magnesium oxide substrate.

[0016] Preferably, the thickness of the heavy metal layer is 2~10 nm;

[0017] The thickness of the ferromagnetic layer is 0.8~20nm;

[0018] The thickness of the superconducting layer is 5-80 nm. Secondly, the present invention also provides a method for fabricating the aforementioned magnetic superconducting memory, characterized by comprising the following steps:

[0019] A heavy metal layer, a ferromagnetic layer, and a superconducting layer are sequentially grown on the substrate.

[0020] Thirdly, the present invention also provides a method for reading and writing the aforementioned magnetic superconducting memory, the method comprising a reading method, the reading method comprising:

[0021] Apply readout current I to the superconducting layer read I c + (M － ) read c + (M + ), where I c + (M + I represents the positive critical current of the superconducting layer in the positive magnetization direction of the ferromagnetic layer. c + (M － () indicates the positive critical current of the superconducting layer under the negative magnetization direction of the ferromagnetic layer;

[0022] When the ferromagnetic layer is magnetized in the positive magnetization direction, the superconducting layer is in the superconducting state, and the longitudinal voltage V of the superconducting layer is... xx =0, which represents logic 1;

[0023] When the ferromagnetic layer is magnetized in the negative magnetization direction, and the superconducting layer is in its normal state, the longitudinal voltage V of the superconducting layer is... xx >0 is represented as logic 0.

[0024] Preferably, the read / write method further includes a write method, the write method comprising:

[0025] Apply write current I to the heavy metal layer write I write Greater than I c + (M － ), I c + (M + Write current I write The direction is parallel to the surface of the heavy metal layer;

[0026] Simultaneously, an in-plane auxiliary magnetic field is applied to the ferromagnetic layer along the direction parallel to the writing current;

[0027] The heavy metal layer generates a spin orbital torque through the spin Hall effect, driving the reversible switching of the magnetization direction of the ferromagnetic layer.​​

[0028] The magnetic superconducting memory, its fabrication method, and its read / write method of the present invention have the following advantages over the prior art:

[0029] 1. The magnetic superconducting memory of the present invention includes a substrate, a heavy metal layer, a ferromagnetic layer, and a superconducting layer; the superconducting layer utilizes the resistance difference between the superconducting state and the normal state to map the magnetization state; the ferromagnetic layer, as a free layer with adjustable magnetization, influences the superconducting critical current (Ic) of the superconducting layer through the magnetization direction. c + and I c - The size of the heavy metal layer; the heavy metal layer generates a spin-orbit torque (SOT) through the spin Hall effect, driving the magnetization reversal of the ferromagnetic layer; this invention achieves an infinite on / off ratio (theoretically approaching infinity) between the superconducting state and the normal state through the superconducting diode magnetoresistance effect (SDMR), combined with current-driven spin-orbit torque (SOT) magnetization reversal technology, realizing a highly efficient and reliable non-volatile memory scheme, completely overcoming the inherent defects of traditional TMR, and significantly improving the signal contrast of the memory cell; the SC / FM / HM (superconducting layer / ferromagnetic layer / heavy metal layer) heterostructure designed in this invention replaces the traditional magnetic tunnel junction (MTJ), reducing material stacking and process complexity; the use of materials compatible with CMOS processes (such as Nb, Co, Pt, etc.) promotes the large-scale integration of low-temperature memory; combining the stable magnetization characteristics of the vertical magnetic anisotropy (PMA) ferromagnetic layer with the low power consumption characteristics of the superconducting state, a high-performance, long-life memory cell is constructed.

[0030] 2. The magnetic superconducting memory of this invention has an ultra-high on / off ratio: through the SDMR mechanism, the resistance difference between the superconducting state and the normal state is significant, achieving high-precision reading without complex signal amplification circuits, thus solving the fundamental problem of low on / off ratio in traditional TMR; the process of this invention is simple and compatible: the core heterogeneous structure of superconducting layer / ferromagnetic layer / heavy metal layer requires only 3 layers of material stacking, which is significantly simplified compared to traditional MTJ (>7 layers); it can be seamlessly compatible with CMOS technology, reducing manufacturing costs; the magnetic superconducting memory of this invention has non-volatility and stability: the perpendicular magnetic anisotropy of the ferromagnetic layer can ensure long-term stability of the magnetization state (e.g., the data retention time of CoFeB in PMA > 10 years); the superconducting state at low temperatures (2.1 K) operation effectively reduces thermal noise interference; the magnetic superconducting memory of the present invention has low power consumption and high speed response: the write operation relies on the SOT effect, and the energy consumption is reduced by more than 30% compared with the traditional STT-MRAM; the superconducting state-normal state switching is nanosecond level response, supporting high-speed read and write; the magnetic superconducting memory of the present invention has broad application prospects: it is suitable for quantum computing, low temperature electronics and high density storage fields; it can be extended to higher temperature regions by optimizing materials (such as replacing Nb with high temperature superconductors). Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the magnetic superconducting memory of the present invention;

[0032] Figure 2 A schematic diagram of the superconducting diode effect (SDE) and its physical mechanism;

[0033] Figure 3 This is a schematic diagram of the magnetoresistive effect (SDMR) and readout mechanism of a superconducting diode.

[0034] Figure 4 This is a schematic diagram of the read / write method of the magnetic superconducting memory of the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0037] In the description of this invention, it should be understood that the orientation or positional relationship indicated by terms such as "above" is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use, or the orientation or positional relationship in which those skilled in the art are usually understood. It is only for the convenience of describing this invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0038] The following provides a detailed description of each example. It should be noted that the order of description of the embodiments below is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0039] This invention provides a magnetic superconducting memory, such as... Figure 1 As shown, it includes:

[0040] Substrate 10;

[0041] Heavy metal layer 11 is located on the surface of substrate 10;

[0042] Ferromagnetic layer 12 is located on the surface of heavy metal layer 11 away from substrate 10;

[0043] The superconducting layer 13 is located on the surface of the ferromagnetic layer 12 away from the substrate 10.

[0044] The heavy metal layer 11 generates a spin orbital torque through the spin Hall effect, which drives the reversible switching of the magnetization direction of the ferromagnetic layer 12.

[0045] The magnetic superconducting memory of the present invention includes a substrate, a heavy metal layer (HM), a ferromagnetic layer (FM), and a superconducting layer (SC). Specifically, the magnetic superconducting memory includes a substrate 10 and a heavy metal layer 11, a ferromagnetic layer 12, and a superconducting layer 13 sequentially stacked on the surface of the substrate 10. The heavy metal layer 11, such as Pt, generates a spin-orbit torque (SOT) through the spin Hall effect, driving the magnetization of the ferromagnetic layer 12 to flip, enabling reversible switching of its magnetization direction. The ferromagnetic layer 12, such as Co, has perpendicular magnetic anisotropy (PMA) and serves as a free layer with adjustable magnetization, influencing the superconducting critical current (I) of the superconducting layer through its magnetization direction. c + and I c - The size of the superconducting layer, such as Nb, serves as the core functional layer for switching between the superconducting and normal states, utilizing the resistance difference between the superconducting and normal states to map the magnetization state. This invention's magnetic superconducting memory is a tunable non-volatile magnetic superconducting random access memory based on the superconducting diode effect. By achieving an infinite on / off ratio (theoretically approaching infinity) between the superconducting and normal states through the superconducting diode magnetoresistance effect (SDMR), and combining it with current-driven spin-orbit torque (SOT) magnetization reversal technology, a highly efficient and reliable non-volatile memory solution is realized, completely overcoming the inherent defects of traditional TMR and significantly improving the signal contrast of the memory cell. The SC / FM / HM (superconducting layer / ferromagnetic layer / heavy metal layer) heterostructure designed in this invention replaces the traditional magnetic tunnel junction (MTJ), reducing material stacking and process complexity. The use of materials compatible with CMOS processes (such as Nb, Co, Pt, etc.) promotes the large-scale integration of low-temperature memory. Combining the stable magnetization characteristics of the vertical magnetic anisotropy (PMA) ferromagnetic layer with the low power consumption characteristics of the superconducting state, a high-performance, long-life memory cell is constructed.

[0046] Specifically, the superconducting state and normal state of the superconducting layer are defined as follows: Superconducting state: When a superconducting material is cooled to below a certain temperature (critical temperature), the material's resistance suddenly disappears, and it exhibits special physical properties such as perfect diamagnetism. This state is called the superconducting state. In the superconducting state, current can flow in the superconductor without loss, and there is no heat loss due to the existence of resistance. Normal state: When the superconducting material is above the critical temperature, it exhibits properties similar to ordinary conductors and has a certain resistance. This state is the normal state.

[0047] In some embodiments, the material of the heavy metal layer 11 includes metals and their alloys with strong spin-orbit coupling, such as platinum (Pt), tantalum (Ta), molybdenum (Mo), ruthenium (Ru), iridium (Ir), and palladium (Pd). Specifically, the alloys are alloys formed from metals such as platinum (Pt), tantalum (Ta), molybdenum (Mo), ruthenium (Ru), iridium (Ir), and palladium (Pd).

[0048] In some embodiments, the superconducting layer 13 is made of superconducting materials mainly composed of metals or their alloys, such as niobium (Nb), niobium titanium (NbTi), niobium tin (Nb3Sn), aluminum (Al), lead (Pb), vanadium germanium (V3Ga).

[0049] In some embodiments, the material of the ferromagnetic layer 12 includes conventional 3d magnetic transition metals such as iron (Fe), cobalt (Co), and nickel (Ni), or ferromagnetic materials with perpendicular magnetic anisotropy such as nickel-iron (NiFe), cobalt-iron-boron (CoFeB), cobalt-platinum alloy (CoPt), and iron-platinum alloy (FePt).

[0050] In some embodiments, the substrate 10 includes a single-crystal silicon substrate, a single-crystal sapphire substrate, or a single-crystal magnesium oxide substrate, etc., in order to induce a good epitaxial growth relationship.

[0051] In some embodiments, the thickness of the heavy metal layer 11 is 2~10nm, which is used to generate spin orbital torque through the spin Hall effect;

[0052] The thickness of the ferromagnetic layer 12 is 0.8~20nm to ensure that the ferromagnetic layer has perpendicular magnetic anisotropy and its thickness is configured to allow current-driven magnetization reversal.

[0053] The thickness of the superconducting layer 13 is 5~80nm to ensure that it stably exhibits the switching characteristics between the superconducting state and the normal state in the temperature range below the superconducting critical temperature.

[0054] The magnetic superconducting memory of the present invention has the shape of a triangle, a square, a rectangle (the aspect ratio can be any value), a circle, or an ellipse (the aspect ratio can be any value). That is to say, the shape of the memory cell is one of the following: triangle, square, rectangle, circle, and ellipse.

[0055] Based on the same inventive concept, the present invention also provides a method for fabricating a magnetic superconducting memory, comprising the following steps:

[0056] A heavy metal layer, a ferromagnetic layer, and a superconducting layer are sequentially grown on the substrate.

[0057] Specifically, high-quality magnetron epitaxial growth, atomic layer deposition, or PVD deposition are used to deposit the various layers of the memory onto the substrate in a bottom-up order.

[0058] Specifically, the following magnetron sputtering process details the fabrication of magnetic superconducting memories, including:

[0059] S1. Substrate Selection and Processing: Select a suitable substrate material, such as sapphire ( Materials such as magnesium oxide (MgO) are cut to appropriate sizes according to experimental requirements. The substrates are then sequentially immersed in acetone and ethanol solutions, and ultrasonically cleaned for 15-20 minutes each in an ultrasonic cleaner to remove surface oil and impurities. After cleaning, the substrates are dried with high-purity nitrogen and placed on the sample stage in the vacuum chamber for later use.

[0060] Target preparation: Prepare target materials for heavy metals (such as platinum Pt, tantalum Ta, etc.), ferromagnetic materials (such as cobalt Co, nickel Ni, etc.), and superconducting materials (such as niobium Nb, etc.), ensure that the purity of the target material meets the experimental requirements, and install it on the corresponding target position of the magnetron sputtering equipment;

[0061] Equipment Inspection and Vacuuming: Check that all components of the magnetron sputtering equipment are properly connected, and that the cooling water circulation system and vacuum system are functioning correctly. Close the vacuum chamber door and start the mechanical pump to pre-evacuate to 10°C. -3 The pressure is on the order of Pa, then the molecular pump is turned on to continue evacuating until the background vacuum of the vacuum chamber reaches 10 Pa. -9 Below Pa;

[0062] S2. Growth of heavy metal layer: Argon (Ar) is introduced as sputtering gas, and its flow rate is adjusted to 15~20 sccm (standard cubic centimeters per minute) through a mass flow controller to stabilize the gas pressure in the chamber at 0.5~1.0 Pa; set the magnetron sputtering power supply corresponding to the heavy metal target material. Taking a platinum target as an example, the power is set to 80~120W. Turn on the sputtering power supply. The growth time is determined according to the required thickness of the heavy metal layer. For example, the growth time for growing a platinum layer with a thickness of 5~10nm is about 5~10 min.

[0063] S3. Growing a ferromagnetic layer: Stop sputtering the heavy metal target, turn off the corresponding sputtering power supply and gas flow rate; switch to the ferromagnetic target, introduce argon gas again, and adjust the flow rate to 15~20 sccm to stabilize the gas pressure in the chamber at 0.5~1.0 Pa; set the sputtering power of the ferromagnetic target, such as 60~100W for the cobalt target, and determine the growth time according to the required thickness. If you want to grow a cobalt layer with a thickness of 10~20 nm, the growth time is about 15~30 min.

[0064] S4. Growth of superconducting layer: Stop sputtering ferromagnetic target material, turn off the corresponding sputtering power supply and gas flow rate; introduce argon gas, adjust the flow rate to 10~15 sccm, and stabilize the chamber pressure at 0.3~0.8 Pa; for niobium target, set the sputtering power to 100~150 W, and the growth time is determined according to the required thickness. If the niobium layer with a thickness of 50~80 nm is to be grown, the growth time is about 30~60 min.

[0065] Based on the same inventive concept, the present invention also provides a method for reading and writing the above-mentioned magnetic superconducting memory, the method including a reading method, the reading method including:

[0066] Apply readout current I to the superconducting layer read I c + (M － ) read c + (M + ), where I c + (M + I represents the positive critical current of the superconducting layer in the positive magnetization direction of the ferromagnetic layer. c + (M － () indicates the positive critical current of the superconducting layer under the negative magnetization direction of the ferromagnetic layer;

[0067] When the ferromagnetic layer is magnetized in the positive magnetization direction, the superconducting layer is in the superconducting state, and the longitudinal voltage V of the superconducting layer is... xx =0, which represents logic 1;

[0068] When the ferromagnetic layer is magnetized in the negative magnetization direction, and the superconducting layer is in its normal state, the longitudinal voltage V of the superconducting layer is... xx >0 is represented as logic 0.

[0069] In some embodiments, the read / write method further includes a write method, which includes:

[0070] Apply write current I to the heavy metal layer write I write Greater than I c + (M － ), I c + (M + Write current I write The direction is parallel to the surface of the heavy metal layer;

[0071] Simultaneously, an in-plane auxiliary magnetic field is applied to the ferromagnetic layer along the direction parallel to the writing current;

[0072] ​​The heavy metal layer generates a spin orbital torque through the spin Hall effect, driving the reversible switching of the magnetization direction of the ferromagnetic layer.

[0073] Specifically, when performing a write operation, such as Figure 4 As shown, a write current I is applied to the heavy metal layer. write Writing current I write The flow passes through a heavy metal layer (HM, such as Pt), and an in-plane auxiliary magnetic field H is applied to the ferromagnetic layer along the direction parallel to the writing current. asist Through the SOT effect of the heavy metal layer, a vertical spin polarization current is generated, realizing the magnetization direction (M) of the ferromagnetic layer. + and M － Reversible switching; applying write current I write The feasible range is extremely large, thus ensuring that the superconducting state does not affect the magnetization process; the writing current value is greater than the critical current of the superconducting layer (Ic). c + (M － ) and I c + (M + To avoid interference from the superconducting state on magnetization switching;

[0074] When performing read / write operations, a read current I is applied to the superconducting layer. read By setting the reading current (I read Its amplitude lies between the critical currents (Ic) of the two magnetization states. c + (M － ), I c + (M + By detecting the longitudinal voltage V of the superconducting layer xx Distinguish logical states: If V xx = 0, the superconducting layer is in the superconducting state, and the magnetization direction of the ferromagnetic layer is the positive magnetization direction M. + , corresponding to logic "1"; if V xx When the magnetization value is greater than 0, the superconducting layer is in its normal state, and the magnetization direction of the ferromagnetic layer is the negative magnetization direction M. － , corresponding to logic "0"; the longitudinal voltage V of the superconducting layer xx The voltage across the superconducting layer in the direction parallel to the readout current; On / off ratio calculation: via SDMR = V xx (M － ) / V xx (M + The on / off ratio is defined, with its theoretical value approaching infinity and its measured value not less than 1 × 10⁻⁶. 6 .

[0075] The device of the present invention is a non-volatile magnetic superconducting memory that is written by a magnetic field and read by an electrical field. This structure can be integrated into an ITIR (1 transistor 1 resistor) memory cell, is compatible with CMOS technology, and is suitable for high-density low-temperature memory.

[0076] Furthermore, Figure 2 This is a schematic diagram of the superconducting diode effect (SDE). By fixing the magnetization direction of the ferromagnetic layer (e.g., M...),... + Breaking the time reversal symmetry (TRS) leads to a difference in the critical current (I) between the forward and reverse currents. c + ≠I c - ), I c + (M) + )≠I c - (M) + (I) c + (M) + ) indicates that the magnetization direction of the ferromagnetic layer is M. + Forward current, I c - (M) + ) indicates that the magnetization direction of the ferromagnetic layer is M. + When the current is reversed, it exhibits current-direction-dependent non-reciprocal transport characteristics, meaning the superconducting state is maintained only in a single current direction, forming a "current diode". The gray area in the figure represents the operable window (ΔI) caused by the difference in critical current. c ,Right now Figure 2 The unidirectional current region is a region in which any current of any magnitude applied has unidirectional conductivity, that is, the current in the positive direction is in the superconducting state and the current in the opposite direction is in the normal state.

[0077] Figure 3 This is a schematic diagram of the magnetoresistive effect (SDMR) and readout mechanism of a superconducting diode. A fixed current direction (e.g., forward current I) is used. + Breaking the TRS makes the magnetization direction (M) + With M － ) directly affects the critical current (I c + (M + ) ≠I c + (M － This exhibits non-reciprocal transport characteristics dependent on the magnetization state, meaning that the superconducting state is maintained only under a specific magnetization direction, forming a "magnetizing diode".

[0078] Figure 3There are two shaded areas, with the dark gray area representing the write current region. During a write operation, the applied pulse write current I... write The requirement is much greater than the critical current (I) of any superconducting layer. c + (M － ), I c + (M + Simultaneously, an in-plane auxiliary magnetic field H is applied to the ferromagnetic layer along a direction parallel to the writing current. asist This ensures the deterministic nature of magnetization reversal; when a pulsed current flows through the heavy metal layer, vertical spin polarization is generated through the spin Hall effect, forming a SOT (Self-Turned Oscillator), which drives the magnetization direction of the ferromagnetic layer from M... + (Vertical upward) Switch to M － (Vertically downwards) (corresponding to the direction of the blank arrow in Figure 4), or switch in the opposite direction. After writing is complete, remove the auxiliary field, and the ferromagnetic layer maintains a stable M through perpendicular magnetic anisotropy (PMA). + Or M － Status. The light gray area is the current reading region. Select an appropriate current I within this region. read Its value satisfies I c + (M － ) read c + (M + When the ferromagnetic layer is magnetized to M + At that time, the superconducting layer in I read The superconducting layer remains in a superconducting state with zero resistance, and the longitudinal voltage V of the superconducting layer is... xx A value of 0 corresponds to state "1"; when magnetized to M － When the superconducting layer enters the normal metallic state, it generates a finite resistance, and the longitudinal voltage V of the superconducting layer... xx The value is not zero, corresponding to state "0", determined by measuring the longitudinal voltage V of the superconducting layer. xx It can distinguish states.

[0079] like Figure 4 As shown, in a superconducting diode magnetic memory, a write operation is performed by applying a write current I to the heavy metal layer (HM, such as Pt). write Simultaneously, an in-plane auxiliary magnetic field H is applied to the ferromagnetic layer along the direction parallel to the writing current. assit The spin-orbit torque (SOT) is used to drive the magnetization direction of the ferromagnetic layer (FM, such as CoFeB) along the vertical axis (M). + With M － The switching between the two is reversible; the read operation is performed at a low temperature below the superconducting critical temperature of the superconducting layer, by applying a read current I to the superconducting layer (SC, such as Nb). read ​​By detecting the longitudinal voltage (V) of the superconducting layer xx Distinguishing magnetization states: When the ferromagnetic layer is M + At this time, the superconducting layer is in a zero-resistance superconducting state ("1"), and the longitudinal voltage V of the superconducting layer is... xx A value of 0 represents a logic 1; when the ferromagnetic layer is M － When the superconducting layer returns to its normal state ("0"), the longitudinal voltage V of the superconducting layer... xx >0 is represented as logic 0.

[0080] The magnetic superconducting memory of the present invention has the following advantages:

[0081] 1. Ultra-high switching ratio: Through the SDMR mechanism, the resistance difference between the superconducting state and the normal state is significant, which can achieve high-precision reading without complex signal amplification circuits, thus solving the fundamental problem of low switching ratio of traditional TMR.

[0082] 2. Simplified process and compatibility: The superconducting / ferromagnetic / heavy metal core heterostructure requires only 3 layers of material stacking, which is much simpler than the traditional MTJ (>7 layers); it can be seamlessly compatible with CMOS technology, reducing manufacturing costs.

[0083] 3. Non-volatility and stability: The ferromagnetic layer with perpendicular magnetic anisotropy can ensure long-term stability of the magnetization state (e.g., the data retention time of CoFeB in PMA is >10 years); the superconducting state operates at low temperature (2.1 K), effectively reducing thermal noise interference.

[0084] 4. Low power consumption and high speed response: The write operation relies on the SOT effect, which reduces power consumption by more than 30% compared with the traditional STT-MRAM; the superconducting state-normal state switching is a nanosecond-level response, supporting high-speed read and write.

[0085] 5. Broad application prospects: It is suitable for quantum computing, low-temperature electronics and high-density storage; it can be extended to higher temperature ranges by optimizing materials (such as replacing Nb with high-temperature superconductors).

[0086] The following detailed embodiments further illustrate the magnetic superconducting memory and its fabrication and read / write methods of this application. This section further explains the invention in conjunction with specific embodiments, but should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in this invention are conventional reagents, methods, and equipment in the art.

[0087] Example 1

[0088] This embodiment provides a magnetic superconducting memory, including a substrate and a heavy metal layer, a ferromagnetic layer, and a superconducting layer stacked sequentially on the surface of the substrate;

[0089] The substrate is a sapphire substrate.

[0090] The heavy metal layer is made of Pt and has a thickness of 5 nm.

[0091] The ferromagnetic layer is made of Co and has a thickness of 0.9 nm.

[0092] The superconducting layer is made of Nb, and the ferromagnetic layer is 30 nm thick.

[0093] The above-mentioned method for fabricating a magnetic superconducting memory includes the following steps:

[0094] S1. A heavy metal layer, a ferromagnetic layer, and a superconducting layer are sequentially grown on a substrate using magnetron sputtering.

[0095] The process parameters for controlling the heavy metal layer are as follows: Argon (Ar) is introduced as the sputtering gas, and its flow rate is adjusted to 20 sccm by the mass flow controller to stabilize the gas pressure in the chamber at 1.0 Pa. The platinum target power is set to 120W, the sputtering power supply is turned on, and a 5nm thick pt layer is grown.

[0096] The process parameters for controlling the ferromagnetic layer are as follows: Argon (Ar) is introduced as the sputtering gas, the flow rate is adjusted to 20 sccm, the pressure in the chamber is stabilized at 1.0 Pa, the cobalt target power is set to 100W, and the growth thickness is 0.9nm.

[0097] The process parameters for controlling the superconducting layer are as follows: argon (Ar) is introduced as the sputtering gas, the flow rate is adjusted to 15 sccm, the pressure in the chamber is stabilized at 0.75 Pa, the niobium target power is set to 120 W, and the growth thickness is 30 nm.

[0098] The aforementioned read / write method for the magnetic superconducting memory includes a read method, which includes:

[0099] Apply readout current I to the superconducting layer read I c + (M － ) read c + (M + ), where I c + (M + I represents the positive critical current of the superconducting layer in the positive magnetization direction of the ferromagnetic layer. c + (M － () indicates the positive critical current of the superconducting layer under the negative magnetization direction of the ferromagnetic layer;

[0100] ​​When the ferromagnetic layer is magnetized in the positive magnetization direction, the superconducting layer is in the superconducting state, and the longitudinal voltage V of the superconducting layer is... xx =0, which represents logic 1;

[0101] When the ferromagnetic layer is magnetized in the negative magnetization direction, and the superconducting layer is in its normal state, the longitudinal voltage V of the superconducting layer is... xx >0 is represented as logic 0;

[0102] The read / write method also includes the write method, which includes:

[0103] Apply write current I to the heavy metal layer write I write Greater than I c + (M － ), I c + (M + Write current I write The direction is parallel to the surface of the heavy metal layer;

[0104] Simultaneously, an in-plane auxiliary magnetic field is applied to the ferromagnetic layer along the direction parallel to the writing current;

[0105] The heavy metal layer generates a spin orbital torque through the spin Hall effect, driving the reversible switching of the magnetization direction of the ferromagnetic layer.

[0106] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for reading and writing a magnetic superconducting memory, the magnetic superconducting memory comprising: Substrate; A heavy metal layer located on the surface of the substrate; A ferromagnetic layer located away from the substrate surface of the heavy metal layer; A superconducting layer located away from the substrate surface of the ferromagnetic layer; wherein the heavy metal layer generates a spin-orbit torque through the spin Hall effect, driving a reversible switching of the magnetization direction of the ferromagnetic layer; characterized in that the read / write method includes a reading method, the reading method comprising: Apply readout current I to the superconducting layer read I c + (M － ) read c + (M + ), where I c + (M + I represents the positive critical current of the superconducting layer in the positive magnetization direction of the ferromagnetic layer. c + (M － () indicates the positive critical current of the superconducting layer under the negative magnetization direction of the ferromagnetic layer;​​ When the ferromagnetic layer is magnetized in the positive magnetization direction, the superconducting layer is in the superconducting state, and the longitudinal voltage V of the superconducting layer is... xx =0, which represents logic 1; When the ferromagnetic layer is magnetized in the negative magnetization direction, and the superconducting layer is in its normal state, the longitudinal voltage V of the superconducting layer is... xx >0 is represented as logic 0.

2. The read / write method for the magnetic superconducting memory as described in claim 1, characterized in that, The read / write method further includes a write method, which includes: Apply write current I to the heavy metal layer write I write Greater than I c + (M － ), I c + (M + Write current I write The direction is parallel to the surface of the heavy metal layer; Simultaneously, an in-plane auxiliary magnetic field is applied to the ferromagnetic layer along the direction parallel to the writing current; The heavy metal layer generates a spin orbital torque through the spin Hall effect, driving the reversible switching of the magnetization direction of the ferromagnetic layer.

3. The read / write method for the magnetic superconducting memory as described in claim 1, characterized in that, The material of the heavy metal layer includes at least one of Pt, Ta, Mo, Ru, Ir, Pd and their alloys.

4. The read / write method for the magnetic superconducting memory as described in claim 1, characterized in that, The superconducting layer is made of at least one of Nb, NbTi, Nb3Sn, Al, Pb, V3Ga and their alloys.

5. The read / write method for the magnetic superconducting memory as described in claim 1, characterized in that, The ferromagnetic layer material includes at least one of Fe, Co, Ni, NiFe alloy, CoFeB, CoPt alloy, and FePt alloy.

6. The read / write method for the magnetic superconducting memory as described in claim 1, characterized in that, The substrate includes any one of silicon substrate, sapphire substrate, and magnesium oxide substrate.

7. The read / write method for the magnetic superconducting memory as described in claim 1, characterized in that, The thickness of the heavy metal layer is 2~10 nm; The thickness of the ferromagnetic layer is 0.8~20nm; The thickness of the superconducting layer is 5-80 nm.

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