True random number generator and method for generating true random numbers

Abstract

The present invention discloses a true random number generator and a method for generating true random numbers. The true random number generator includes a random number generation module, which comprises: a conductive layer, with a first electrode and a second electrode for passing a first current respectively provided at both ends, and a plurality of magnetic tunnel junctions arranged in parallel on the conductive layer. Each magnetic tunnel junction includes: a first magnetic layer located above the conductive layer; a spin current compensation layer located above the first magnetic layer; an insulating barrier layer located above the spin current compensation layer; a second magnetic layer located above the insulating barrier layer; and a pinning layer located above the second magnetic layer. A third electrode is provided at the end of the pinning layer of each magnetic tunnel junction away from the second magnetic layer. The first and third electrodes are used to pass a second current. The true random number generator provided by the present invention has high integration, good randomness, and a long service life, and has excellent application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of information security and cryptography, and in particular to a true random number generator and a method for generating true random numbers. Background Art

[0002] Random numbers play a crucial role in cryptographic protocols, key management, digital signatures, and identity authentication. In existing technologies, random number generators include pseudo-random number generators and true random number generators. True random number generators generally use hardware to generate random numbers. For example, they leverage the natural randomness of physical sources, such as thermal noise, radioactive decay, electronic circuit noise, light source noise, electronic oscillator frequency jitter, and quantum noise. These sources possess unpredictable natural random properties and offer greater security in cryptographic applications.

[0003] The conventional true random number generators of magnetic information devices include those based on spin-transfer torque (STT), spin-orbit torque (SOT) and low barrier nanomagnet technology (LBNM).

[0004] Among them, true random number generators based on the spin transfer torque effect (STT) utilize spin valves or magnetic tunnel junctions (MTJs). Under thermal noise, the magnetic moment of the free layer of the MTJ is disturbed. When a spin-polarized current flows perpendicularly through the layers, the magnetic moment of the free layer is affected by the spin transfer torque. When the spin transfer torque is large enough, it induces a random flip in the magnetic moment of the free layer. When the magnetic moment of the free layer is parallel to that of the reference layer, the MTJ exhibits a low-resistance state (logical "0"). When the magnetic moment of the free layer is antiparallel to that of the reference layer, the MTJ exhibits a high-resistance state (logical "1"), thereby generating a string of numbers with equal probability of "0" and "1".

[0005] True random number generators based on the spin transfer torque effect (STT) require a spin-polarized current to pass through a fragile oxide tunneling layer, resulting in a shorter service life. In addition, true random number generators based on the spin transfer torque effect (STT) require the write current to have precise pulse amplitude and pulse width. Therefore, the conditions for its stable generation of true random numbers are relatively harsh.

[0006] A true random number generator based on the spin-orbit coupling (SOT) effect consists of a perpendicularly magnetized heterojunction composed of a heavy metal, ferromagnetic, and non-magnetic structure. In this perpendicular heterojunction, when an in-plane current flows horizontally through the heavy metal layer, a horizontally polarized pure spin current accumulates at the interface between the ferromagnetic and heavy metal layers due to the spin-orbit coupling (SOT) effect. This generates a torque (spin-orbit torque) on the magnetic moment of the ferromagnetic layer, pulling it horizontally in the plane. Due to thermal perturbations, when the horizontal current is removed, the magnetic moment of the ferromagnetic layer of the perpendicular heterojunction randomly flips upward or downward with equal probability (50% each). Because the anomalous Hall resistance is related to the magnetic moment, the perpendicular heterojunction exhibits a high-resistance state (logical "1") and a low-resistance state (logical "0") due to the magnetic moment flipping of the ferromagnetic layer, thereby generating a random digital string with equal probability of "0" and "1".

[0007] In the process of pulling the magnetic moment of the ferromagnetic layer to the horizontal direction based on the spin-orbit coupling effect (SOT), the direction of the magnetic moment is offset to a certain extent. When the horizontal current is removed, the magnetic moment of the ferromagnetic layer in the perpendicular magnetization heterojunction is difficult to maintain an equal probability (50% each) of flipping upward or downward. Therefore, the true random number generator based on the spin-orbit coupling effect (SOT) has poor randomness. In addition, the true random number generator based on the spin-orbit coupling effect (SOT) requires the preparation of a magnetic stack device without shape offset, which has high process requirements. The current density required to generate true random numbers is also large (the horizontal current must be large enough to pull the magnetic moment of the ferromagnetic layer to the difficult-to-magnetize horizontal direction): often 10 7 -10 8 A / cm 2 Above the current density, the large current passing through the perpendicular magnetized heterojunction will not only lead to excessive energy consumption, but also the thermal effect will greatly reduce the service life of the device.

[0008] The principle of generating true random numbers using low-barrier nanomagnet technology (LBNM) is that, in the presence of ambient thermal noise, the magnetic moment of a low-barrier nanoperpendicular magnet undergoes a continuous, uncontrollable, random upward or downward flip. The frequency of this flip depends on the frequency of the ambient thermal noise, and the ability to flip depends on the energy amplitude of the thermal noise. The occurrence of this flip is interpreted as a logical "1" or a logical "0." True random number generators based on LBNM technology cannot store generated random numbers in situ, which affects data reuse. Furthermore, random number generation passively relies on ambient noise, resulting in slow generation and an unstable frequency. Summary of the Invention

[0009] In view of at least one drawback of the prior art, the present invention provides a true random number generator and a method for generating true random numbers.

[0010] The true random number generator includes: a random number generation module, wherein the random number generation module includes:

[0011] A conductive layer, having a first electrode and a second electrode at both ends, wherein the first electrode and the second electrode are used to pass a first current; and

[0012] A plurality of magnetic tunnel junctions are arranged in parallel on the conductive layer;

[0013] Wherein, each of the plurality of magnetic tunnel junctions comprises:

[0014] a first magnetic layer located on the conductive layer, having an easy magnetization direction perpendicular to an interface between the conductive layer and the first magnetic layer, and configured such that, under the action of Joule heat of the first current, the magnetic moment of the first magnetic layer overcomes a reversal energy barrier and randomly flips in an upward or downward direction perpendicular to the interface;

[0015] a spin current cancellation layer, located on the first magnetic layer, for canceling the spin-orbit moment generated by the spin current generated at the interface between the conductive layer and the first magnetic layer on the magnetic moment of the first magnetic layer;

[0016] an insulating barrier layer, located on the spin current compensation layer;

[0017] a second magnetic layer, located on the insulating barrier layer, with an easy magnetization direction perpendicular to an interface between the insulating barrier layer and the second magnetic layer; and

[0018] a pinning layer, located on the second magnetic layer, for fixing the magnetic moment direction of the second magnetic layer;

[0019] Wherein, a third electrode is provided at one end of the pinned layer of each magnetic tunnel junction in the plurality of magnetic tunnel junctions away from the second magnetic layer, and the first electrode and the third electrode are used for passing a second current.

[0020] According to one aspect of the present invention, each of the plurality of magnetic tunnel junctions further comprises:

[0021] The capping layer is located on the pinning layer and is used to protect the layers thereunder.

[0022] According to one aspect of the present invention, the first magnetic layer, the spin current compensation layer, the insulating barrier layer, the second magnetic layer, the pinned layer and the cap layer are thin film layers with the same cross-sectional shape, and the first magnetic layer, the spin current compensation layer, the insulating barrier layer, the second magnetic layer, the pinned layer and the cap layer are stacked in the central area of ​​the conductive layer.

[0023] According to one aspect of the present invention, the first current includes a pulse current with a preset interval, and the second current is passed at the preset interval to measure the magnetic resistance of each magnetic tunnel junction in the multiple magnetic tunnel junctions, and obtain a random number sequence based on the magnetic resistance.

[0024] According to one aspect of the present invention, the current intensity and / or pulse width of the first current is determined according to the switching energy barrier of the first magnetic layer.

[0025] According to one aspect of the present invention, the pulse period of the first current determines the rate of generating true random numbers.

[0026] According to one aspect of the present invention, the conductive layer is made of heavy metal material or topological insulator material.

[0027] According to one aspect of the present invention, the first magnetic layer is made of soft magnetic material.

[0028] According to one aspect of the present invention, the spin current cancellation layer is made of the same material as that of the conductive layer or a material having the same sign of the spin Hall angle as that of the conductive layer.

[0029] According to one aspect of the present invention, the second magnetic layer is made of ferromagnetic material.

[0030] According to one aspect of the present invention, the cap layer is made of a non-ferrous conductive metal material.

[0031] According to one aspect of the present invention, the insulating barrier layer is made of metal oxide material.

[0032] According to one aspect of the present invention, the pinning layer is made of antiferromagnetic material.

[0033] According to one aspect of the present invention, the random number generation module further includes a substrate located below the conductive layer, and the substrate includes a silicon substrate.

[0034] According to one aspect of the present invention, the plurality of magnetic tunnel junctions are configured such that a distance between two adjacent magnetic tunnel junctions can ensure that no magnetic coupling is generated between the two adjacent magnetic tunnel junctions.

[0035] The present invention also provides a method for generating true random numbers using the true random number generator as described above, comprising:

[0036] Passing the first current through the first electrode and the second electrode, wherein the first current includes a pulse current with a preset interval;

[0037] At the preset interval, the second current is supplied to the first electrode and the third electrode to measure the magnetic resistance of each magnetic tunnel junction in the plurality of magnetic tunnel junctions, and a random number sequence is obtained according to the magnetic resistance.

[0038] According to one aspect of the present invention, the Joule heat generated by the first current in one pulse period is greater than the energy required for the magnetic moment of the first magnetic layer to be switched.

[0039] According to one aspect of the present invention, the Joule heat generated by the second current in the preset interval is smaller than the energy required for the magnetic moment of the first magnetic layer to be switched.

[0040] According to one aspect of the present invention, the method further comprises: controlling the rate of generating true random numbers by controlling the pulse period of the first current.

[0041] The true random number generator and method for generating true random numbers provided by the present invention utilize the Joule heating effect of an electric current to drive the magnetic moment of a magnetic layer to undergo random reversals. One reversal cycle generates a random bit, and the magnetic moment maintains its state after the current is removed. The generated random bit is non-volatile and readable. A spin current cancellation layer is provided to offset the spin-orbit moment from the conductive layer, overcoming the problem of the magnetic moment of a perpendicularly magnetized heterojunction device under the spin-orbit coupling effect being difficult to flip upward and downward with equal probability, resulting in a more stable random number generation. Furthermore, compared to low-barrier nanomagnet technology, the timing of magnetic moment reversal is actively controlled by applying a small current, and the rate of random number generation is controlled by adjusting the current pulse width, making it more proactive.

[0042] Furthermore, the present invention provides multiple magnetic tunnel junctions on the conductive layer, and applies a pulse current of a certain width and amplitude in the current path. The Joule heat generated will overcome the reversal barrier of the magnetic moment in the low-barrier perpendicular nanomagnetic structure (first magnetic layer) in the magnetic tunnel junction. The magnetic layer in each unit magnetic tunnel junction in the current path will independently undergo magnetization reversal, and the resistance value generated is detected by the tunneling magnetoresistance effect, where the high resistance state is "1" and the low resistance state is "0". In this way, multiple random number sequences can be generated by applying a current pulse once, and the reversal state of each magnetic tunnel junction after overcoming the same barrier is random, which can significantly improve the integration, randomness and service life of the device and reduce energy consumption.

[0043] The true random number generator provided by the present invention has a simple structure, a small device size, low energy consumption, and is easy to integrate into various portable devices. The method for generating true random numbers is simple and has good randomness, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without exceeding the scope of protection required by this application.

[0045] Figure 1 The figure shows a front view of a random number generating module of a true random number generator provided by one embodiment of the present invention.

[0046] Figure 2 Shown Figure 1 The top view of the random number generation module of the true random number generator is shown.

[0047] Figure 3 Shown Figure 1 Schematic diagram of the longitudinal section of part A.

[0048] Figure 4 A partial longitudinal cross-sectional schematic diagram of a random number generating module of a true random number generator provided by another embodiment of the present invention is shown.

[0049] Figure 5 A partial longitudinal cross-sectional schematic diagram of a random number generating module of a true random number generator provided by yet another embodiment of the present invention is shown.

[0050] Figure 6 A method for generating true random numbers provided by an embodiment of the present invention is shown.

[0051] Figure 7 FIG. 1 shows the pulse current passed into the true random number generator provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0053] In this specification, when a component (or, region, layer, part, etc.) is referred to as being "on", "connected to" or "coupled to" another component, this means that the component can be directly on, connected to or coupled to the other component or a third component can exist between them.

[0054] In the drawings, the thickness, proportion and size of components are exaggerated for efficient description. As used herein, the term "and / or" includes all one or more combinations defined by the relevant components.

[0055] Terms such as first and second can be used to describe various components, but components should not be limited by these terms. These terms can only be used to distinguish one component from other components. For example, without departing from the scope of the present invention, a first component can be referred to as a second component, and similarly, a second component can also be referred to as a first component. Unless otherwise specified, terms in the singular may include plural forms.

[0056] In addition, terms such as "under," "beneath," "over," and "on" are used to describe the relationship of components shown in the drawings. These terms are relative concepts and are described based on the directions shown in the drawings.

[0057] It should be understood that terms such as “include,” “comprises,” and “has” when used in this document specify the presence of stated features, quantities, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, quantities, steps, operations, components, parts, or combinations thereof.

[0058] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. Such terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and should not be interpreted as having an idealized or overly formal meaning unless explicitly defined in this application.

[0059] Figure 1-3 FIG1 shows a random number generation module 100 of a true random number generator provided by an embodiment of the present invention, which includes a conductive layer 110 and a plurality of magnetic tunnel junctions (MTJs). Figure 1 and Figure 2 They are respectively a front view and a top view of the random number generating module 100, Figure 3 for Figure 1 Schematic diagram of the longitudinal section of part A.

[0060] In this embodiment, the conductive layer 110 is a strip-shaped structure, with a first electrode T1 and a second electrode T2 provided at its two ends. The first electrode T1 and the second electrode T2 are used to pass a first current. In other embodiments of the present invention, the conductive layer 110 may also have other shapes.

[0061] Optionally, the conductive layer 110 is made of a material with a strong spin coupling effect, such as heavy metal materials Pt, Ta, and W, topological insulator materials Bi2Se3, Sb2Te3, and Bi2Te3, and novel materials MoS2 and PtTe2. Optionally, the conductive layer 110 is micron-sized to increase the width of the current path.

[0062] like Figure 1 As shown, a plurality of magnetic tunnel junctions are arranged in parallel on the conductive layer 110, and the plurality of magnetic tunnel junctions include a first magnetic tunnel junction MTJ1 to an nth magnetic tunnel junction MTJn. In the present invention, n is a positive integer greater than 1. This embodiment is described by taking n≥4 as an example. Among them, the structures of the first magnetic tunnel junction MTJ1 to the nth magnetic tunnel junction MTJn are all the same. Optionally, in the present invention, the plurality of magnetic tunnel junctions are configured so that the spacing between two adjacent magnetic tunnel junctions can ensure that no magnetic coupling is generated between the two adjacent magnetic tunnel junctions. That is, no magnetic coupling will be generated between the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2, and no magnetic coupling will be generated between the n-1th magnetic tunnel junction MTJn-1 and the nth magnetic tunnel junction MTJn. Optionally, each magnetic tunnel junction is of nanometer size.

[0063] The following combination Figure 3 , the structure of the first magnetic tunnel junction MTJ1 is described in detail. Figure 3 In the figure, the geometric center of the conductive layer 110 of the strip structure is the origin of the three-dimensional rectangular coordinate, the extending direction of the strip structure is the X-axis, and the Z-axis is perpendicular to the X-axis and along the stacking direction of the first magnetic tunnel junction MTJ1.

[0064] like Figure 3 As shown, the first magnetic tunnel junction MTJ1 includes a first magnetic layer 120 , a spin current cancellation layer 130 , an insulating barrier layer 140 , a second magnetic layer 150 and a pinning layer 160 .

[0065] The first magnetic layer 120 is located on the conductive layer 110. Its easy magnetization direction is perpendicular to the interface between the conductive layer 110 and the first magnetic layer 120. In the present invention, the first magnetic layer 120 is configured so that under the Joule heating of the first current, the magnetic moment of the first magnetic layer overcomes the reversal energy barrier and randomly flips in an upward or downward direction perpendicular to the interface.

[0066] The spin current compensation layer 130 is located on the first magnetic layer 120 and is used to compensate the spin-orbit moment of the first magnetic layer 120 caused by the spin current generated at the interface between the conductive layer 110 and the first magnetic layer 120 .

[0067] In the present invention, the first magnetic layer 120 is made of a magnetocrystalline material with magnetic anisotropy, and the magnetization curve varies with the direction of the crystal axis. In some directions, the external magnetic field required to reach a saturated magnetization state is the smallest, and this direction is called the easy magnetization direction. When the magnetocrystalline material is magnetized in the easy magnetization direction, the magnetic potential energy is the lowest; in other directions, the external magnetic field required to reach a saturated magnetization state is the largest, and this direction is called the difficult magnetization direction. When the magnetocrystalline material is magnetized in the difficult magnetization direction, the magnetic potential energy is the highest.

[0068] Optionally, the first magnetic layer 120 is made of a material with a small damping coefficient, low coercive force, perpendicular magnetic anisotropy, and a low magnetic moment reversal energy barrier, such as multilayer soft magnetic materials such as Co, CoFe alloy, CoNiCo, and CoAuCo.

[0069] When formed into a thin film, the first magnetic layer 120 is primarily affected by shape anisotropy (demagnetization energy), with its easy magnetization direction parallel to the film surface. When the first magnetic layer 120 is combined with the conductive layer 110, due to the interface effect, the easy magnetization direction of the first magnetic layer 120, induced by the conductive layer 110, is perpendicular to the interface between the first magnetic layer 120 and the conductive layer 110.

[0070] After a first current is passed through the conductive layer 110, the Joule heating effect of the first current causes the magnetic moment of the first magnetic layer 120 to randomly flip. The magnetic moment of the first magnetic layer 120 flips toward the direction of lowest magnetic potential energy, i.e., it randomly flips upward or downward along the easy magnetization direction, perpendicular to the interface between the conductive layer 110 and the first magnetic layer 120. Optionally, the first magnetic layer 120 is fabricated as a single-domain two-state magnetic device, i.e., the magnetic moment of the first magnetic layer 120 is oriented in the same direction at the same time. Using the magnetic moment direction of the first magnetic layer 120 as the information carrier, true random numbers are generated through the randomness of magnetic moment flipping. Thermal disturbances are a true random entropy source in nature. Therefore, the probability of the magnetic moment of the first magnetic layer 120 flipping to either the upward or downward direction, perpendicular to the interface between the conductive layer 110 and the first magnetic layer 120, is 50%. Different magnetic moment directions correspond to different Hall resistances. By measuring the Hall resistance, a true random number sequence can be obtained.

[0071] However, at the interface between the first magnetic layer 120 and the conductive layer 110, electrons are asymmetrically scattered due to the spin-orbit coupling effect (SOT), accumulating single-spin electrons at the interface between the first magnetic layer 120 and the conductive layer 110. These single-spin electrons, through their spin-orbit moment, change the direction of the magnetic moment of the first magnetic layer 120, pulling the magnetic moment of the first magnetic layer 120 from perpendicular to the interface between the first magnetic layer 120 and the conductive layer 110 to parallel to the interface. During this process, the magnetic moment of the first magnetic layer 120 shifts, resulting in the inability to flip to an upward or downward direction perpendicular to the interface with equal probability (50% each) even after the first current is removed.

[0072] In the present invention, the spin current cancellation layer 130 can offset the torque generated by electron spin. The spin current cancellation layer 130 is prepared on the first magnetic layer 120. When the first current is passed through the conductive layer 110, the current also flows through the spin current cancellation layer 130. Due to the spin-orbit coupling effect (SOT), the electrons are asymmetrically scattered, and electrons with a single spin direction accumulate at the interface between the first magnetic layer 120 and the spin current cancellation layer 130. Optionally, the spin current cancellation layer 130 is made of the same material as the conductive layer 110. By adjusting the growth thickness of the spin current cancellation layer 130, the spin-orbit moments generated at the upper and lower interfaces of the first magnetic layer 120 are equal in magnitude and opposite in direction, thereby canceling out the spin-orbit moments at the upper and lower interfaces, and causing the magnetic moment of the first magnetic layer 120 to randomly flip only under thermal disturbances.

[0073] The insulating barrier layer 140 is located on the spin current compensation layer 130. Optionally, the insulating barrier layer 140 is made of a metal oxide material, and optionally includes Al2O3.

[0074] The second magnetic layer 150 is located on the insulating barrier layer 140, and its easy magnetization direction is perpendicular to the interface between the insulating barrier layer 140 and the second magnetic layer 150. Optionally, the second magnetic layer 150 is made of a material with a large damping coefficient, high coercivity, and magnetic anisotropy, and optionally includes a ferromagnetic material.

[0075] In the present invention, the insulating barrier layer 140, on the one hand, induces the first magnetic layer 120 to have magnetic anisotropy perpendicular to the interface through the interface effect; on the other hand, it is also used as the insulating layer of the magnetic tunnel junction (MTJ). The "sandwich" structure of the magnetic tunnel junction (MTJ) composed of the first magnetic layer 120, the insulating barrier layer 140, and the second magnetic layer 150 is used to generate the magnetic resistance of the magnetic tunnel junction.

[0076] The pinning layer 160 is located on the second magnetic layer 150. The pinning layer 160 is used to fix the magnetic moment direction of the second magnetic layer 150. Under the induction of the pinning layer 160, the magnetic moment of the second magnetic layer 150 can be fixed in an upward or downward direction perpendicular to the interface between the second magnetic layer 150 and the pinning layer 160. Optionally, the pinning layer 160 is made of an antiferromagnetic material, optionally including IrMn or NiMn. In the present invention, Figure 1 As shown, a third electrode R is provided at the top of each of the multiple magnetic tunnel junctions (in this embodiment, the top is the end of the pinned layer 160 away from the second magnetic layer 150), wherein the first electrode T1 and the third electrode R are used to pass the second current. In this embodiment, each third electrode R is identical (i.e., made of the same material). Of course, in other embodiments, each third electrode R may be different (i.e., made of different materials).

[0077] In the first magnetic layer 120, Joule heat driving magnetization reversal requires reaching a certain temperature. Therefore, when increasing device density (i.e., reducing the width of the conductive path), while maintaining a fixed channel length-to-width ratio and the same heat dissipation conditions, the current in each device must remain constant to achieve the same temperature rise. This increases the current density required to reverse the magnetic moment of the first magnetic layer 120, increasing power consumption and shortening device life. This makes it difficult to scale down the TRNG and increase its integration density.

[0078] In the present invention, multiple magnetic tunnel junctions are provided on the conductive layer 110, and a pulse current of a certain width and amplitude is applied to the current path. The Joule heat generated will overcome the reversal barrier of the magnetic moment in the low-barrier perpendicular nanomagnetic structure (first magnetic layer 120) in the magnetic tunnel junction. The magnetic layer in each unit magnetic tunnel junction in the current path will independently undergo magnetization reversal, and the resistance value generated is detected by the tunneling magnetoresistance effect, where the high resistance state is "1" and the low resistance state is "0". In this way, multiple random number sequences can be generated by applying a current pulse once, and the reversal state of each magnetic tunnel junction after overcoming the same barrier is random, which can significantly improve the integration, randomness and service life of the device and reduce energy consumption.

[0079] In the present invention, the first current optionally includes a pulse current with a preset interval. Optionally, the first current is a relatively large pulse current. The first current has a preset interval along the X-axis direction at the first electrode T1 and the second electrode T2. Optionally, the heat generated by the first current during a pulse cycle is greater than the energy required for random reversal of the magnetic moment of the first magnetic layer 120. Therefore, the current intensity and pulse width of the first current are determined based on the reversal energy barrier of the magnetic moment of the first magnetic layer 120.

[0080] A second current is passed through the first electrode T1 and the third electrode R at preset intervals along the Z-axis to measure the magnetoresistance of the magnetic tunnel junction and generate a random number sequence based on the magnetoresistance. Optionally, when the first current is applied, the magnetic moment of the first magnetic layer 120 undergoes random flipping. Between pulses or during the intervals between pulses, or when the pulsed current is removed, a random number can be generated by detecting the magnetoresistance of the magnetic tunnel junction. Therefore, by controlling the pulse interval of the first current, the rate of true random number generation can be controlled.

[0081] The Joule heat generated by the second current within one cycle (the preset interval of the first current) is insufficient to cause the magnetic moment of the first magnetic layer 120 to overcome the reversal energy barrier and flip. That is, under the action of the second current, the direction of the magnetic moment of the first magnetic layer 120 remains unchanged, maintaining its flipped state. The magnetic moment of the second magnetic layer 150, however, is pinned by the pinning layer 160, exhibiting perpendicular magnetic anisotropy and maintaining a single direction. When the first current is applied, the magnetic moment of the first magnetic layer 120 randomly flips in an upward or downward direction perpendicular to the interface between the first magnetic layer 120 and the conductive layer 110. At this point, the magnetic moments of the first magnetic layer 120 and the second magnetic layer 150 are either parallel or antiparallel. Due to the tunneling magnetoresistance effect, when the magnetic moments of the first magnetic layer 120 and the second magnetic layer 150 are parallel, a lower magnetoresistance is measured; when the magnetic moments of the first magnetic layer 120 and the second magnetic layer 150 are antiparallel, a higher magnetoresistance is measured. During the intermittent period after the first current is removed, a second current is applied at a preset interval. Due to the presence of n third electrodes R, each magnetic tunnel junction generates a random bit, allowing multiple magnetoresistors to be generated simultaneously. By defining different resistance values ​​as logical "0" and "1," repeated operations can output a random number sequence. This allows for the generation of a large number of high-quality random sequences by applying a single flip pulse current and performing low-current testing on multiple channels, significantly improving device integration and service life while reducing energy consumption.

[0082] The true random number generator and method for generating true random numbers provided by the present invention utilize the Joule heating effect of an electric current to drive the magnetic moment of a magnetic layer to undergo random reversals. One reversal cycle generates a random bit, and the magnetic moment maintains its state after the current is removed. The generated random bit is non-volatile and readable. A spin current cancellation layer is provided to offset the spin-orbit moment from the conductive layer, overcoming the problem of the magnetic moment of a perpendicularly magnetized heterojunction device under the spin-orbit coupling effect being difficult to flip upward and downward with equal probability, resulting in a more stable random number generation. Furthermore, compared to low-barrier nanomagnet technology, the timing of magnetic moment reversal is actively controlled by applying a small current, and the rate of random number generation is controlled by adjusting the current pulse width, making it more proactive.

[0083] Furthermore, the present invention provides multiple magnetic tunnel junctions on the conductive layer, and applies a pulse current of a certain width and amplitude in the current path. The Joule heat generated will overcome the reversal barrier of the magnetic moment in the low-barrier perpendicular nanomagnetic structure (first magnetic layer) in the magnetic tunnel junction. The magnetic layer in each unit magnetic tunnel junction in the current path will independently undergo magnetization reversal, and the resistance value generated is detected by the tunneling magnetoresistance effect, where the high resistance state is "1" and the low resistance state is "0". In this way, multiple random number sequences can be generated by applying a current pulse once, and the reversal state of each magnetic tunnel junction after overcoming the same barrier is random, which can significantly improve the integration, randomness and service life of the device and reduce energy consumption.

[0084] The true random number generator provided by the present invention has a simple structure, a small device size, low energy consumption, is easy to be integrated into various portable devices, and has a good application prospect.

[0085] Figure 4 A partial longitudinal cross-sectional schematic diagram of a random number generating module of a true random number generator provided by another embodiment of the present invention is shown. The portion corresponds to Figure 1 Part A. Figure 3 Unlike the first magnetic tunnel junction MTJ1 in section A shown in FIG, the first magnetic tunnel junction MTJ1-a in this embodiment further includes a capping layer 170. The capping layer 170 is located above the pinning layer 160 and is used to protect the underlying layers. Optionally, the capping layer 170 is made of a non-ferrous conductive metal material, such as Ta, Ti, or Cu.

[0086] In this embodiment, the third electrode R is located on the capping layer 170 , that is, on an end of the capping layer 170 away from the pinning layer 160 .

[0087] Figure 5 A partial longitudinal cross-sectional schematic diagram of a random number generating module of a true random number generator provided by another embodiment of the present invention is shown, which also corresponds to Figure 1 Part A. Figure 4 The difference from the structure shown is that the random number generation module in this embodiment further includes a substrate 180 , which is located below the conductive layer 110 . Optionally, the substrate includes a silicon substrate or other materials with low surface roughness.

[0088] In the above embodiments, the conductive layer 110 is shown as a strip structure. Optionally, the first magnetic layer 120, the spin current compensation layer 130, the insulating barrier layer 140, the second magnetic layer 150, the pinning layer 160 and the capping layer 170 are thin film layers with the same cross-sectional shape (i.e., all are strip-shaped). Of course, in other embodiments of the present invention, they can also be other shapes.

[0089] Optionally, a conductive layer 110, a first magnetic layer 120, a spin current compensation layer 130, an insulating barrier layer 140, a second magnetic layer 150, a pinning layer 160 and a capping layer 170 are prepared in sequence on the substrate 180, and the first magnetic layer 120, the spin current compensation layer 130, the insulating barrier layer 140, the second magnetic layer 150, the pinning layer 160 and the capping layer 170 are stacked in the central area of ​​the strip-shaped conductive layer 110 by etching.

[0090] Figure 6 A method for generating true random numbers using the true random number generator provided by an embodiment of the present invention is shown, including the following steps S610 and S620.

[0091] S610: Applying a first current to the first electrode and the second electrode.

[0092] The first current includes a pulse current with a preset interval.

[0093] S620: At a preset interval, a second current is supplied to the first electrode and the third electrode to measure the magnetic resistance of each magnetic tunnel junction in the plurality of magnetic tunnel junctions, and obtain a random number sequence according to the magnetic resistance.

[0094] The method for generating true random numbers provided by the present invention is simple, has good randomness, and has good application prospects.

[0095] Figure 7 The diagram shows a first current and a second current that are periodically alternating and fed into a random number generation module of a true random number generator according to an embodiment of the present invention, wherein the first current is a high-amplitude pulse current and the second current is a low-amplitude pulse current.

[0096] Optionally, the Joule heat generated by the high-amplitude pulse current during one pulse period P is greater than the energy required for random reversal of the magnetic moment of the first magnetic layer 120. Optionally, the Joule heat generated by the low-amplitude pulse current during one pulse period P is less than the energy required for random reversal of the magnetic moment of the first magnetic layer 120. Within one pulse period P, a high-amplitude pulse current is first applied to cause the magnetic moment of the first magnetic layer 120 to overcome the reversal energy barrier and undergo random reversal upward or downward perpendicular to the interface. Due to the characteristics of the first magnetic layer 120, the direction of the magnetic moment does not change after magnetization. After the preset interval of the first current, a low-amplitude pulse current is applied during the preset interval to detect the magnetoresistance of each magnetic tunnel junction along the Z-axis. Different resistance values ​​are defined as logical "0" and "1," respectively. Repeating this operation can output a random number sequence. In the next pulse period P, a high-amplitude pulse current is passed through the first magnetic layer 120 to magnetize it again, causing the direction of the magnetic moment to flip randomly. Then, a low-amplitude current is passed through the magnetic resistance of each magnetic tunnel junction in the Z-axis direction. By periodically repeating the operation, a random number sequence can be output.

[0097] As previously described, when the first current is applied, the magnetic moment of first magnetic layer 120 undergoes random flipping. Between pulses or during the pause period after the pulse current is removed, a random number can be obtained by detecting the magnetoresistance of the magnetic tunnel junction. Therefore, the method provided by the present invention can also control the rate of true random number generation by controlling the pulse period of the first current.

[0098] The above description is merely an example embodiment of the present disclosure and is not intended to limit the present disclosure. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art may still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included within the scope of protection of the present disclosure.

Claims

1. A true random number generator, characterized in that Comprising a random number generation module, wherein the random number generation module comprises: A conductive layer, having a first electrode and a second electrode at both ends, wherein the first electrode and the second electrode are used to pass a first current; and A plurality of magnetic tunnel junctions are arranged in parallel on the conductive layer; Wherein, each of the plurality of magnetic tunnel junctions comprises: a first magnetic layer located on the conductive layer, having an easy magnetization direction perpendicular to an interface between the conductive layer and the first magnetic layer, and configured such that, under the action of Joule heat of the first current, the magnetic moment of the first magnetic layer overcomes a reversal energy barrier and randomly flips in an upward or downward direction perpendicular to the interface; a spin current cancellation layer, located on the first magnetic layer, for canceling the spin-orbit moment generated by the spin current generated at the interface between the conductive layer and the first magnetic layer on the magnetic moment of the first magnetic layer; an insulating barrier layer, located on the spin current compensation layer; a second magnetic layer, located on the insulating barrier layer, with an easy magnetization direction perpendicular to an interface between the insulating barrier layer and the second magnetic layer; and a pinning layer, located on the second magnetic layer, for fixing the magnetic moment direction of the second magnetic layer; Wherein, a third electrode is provided at one end of the pinned layer of each magnetic tunnel junction in the plurality of magnetic tunnel junctions away from the second magnetic layer, and the first electrode and the third electrode are used for passing a second current.

2. The true random number generator according to claim 1, wherein Each of the plurality of magnetic tunnel junctions further comprises: a capping layer, located on the pinning layer and used to protect the layers thereunder; Wherein, the third electrode is arranged on the cap layer.

3. The true random number generator according to claim 2, characterized in that The first magnetic layer, the spin current compensation layer, the insulating barrier layer, the second magnetic layer, the pinned layer and the cap layer are thin film layers with the same cross-sectional shape, and the first magnetic layer, the spin current compensation layer, the insulating barrier layer, the second magnetic layer, the pinned layer and the cap layer are stacked in the central area of ​​the conductive layer.

4. The true random number generator according to claim 1, wherein The first current includes a pulse current with a preset interval, and the second current is passed at the preset interval to measure the magnetic resistance of each magnetic tunnel junction in the plurality of magnetic tunnel junctions, and obtain a random number sequence according to the magnetic resistance.

5. The true random number generator according to claim 4, characterized in that The current intensity and / or pulse width of the first current is determined according to the switching energy barrier of the first magnetic layer.

6. The true random number generator according to claim 4, characterized in that The pulse period of the first current determines the rate of generating true random numbers.

7. The true random number generator according to claim 1, wherein: The conductive layer is made of heavy metal material or topological insulator material; The first magnetic layer is made of soft magnetic material; The spin current compensation layer is made of the same material as the conductive layer or a material having the same spin Hall angle sign as the conductive layer; The insulating barrier layer is made of metal oxide material; The second magnetic layer is made of ferromagnetic material; and / or The pinning layer is made of antiferromagnetic material.

8. The true random number generator according to claim 2, wherein: The cap layer is made of non-ferrous conductive metal material.

9. The true random number generator according to claim 1, wherein: The random number generating module further includes a substrate located below the conductive layer, wherein the substrate includes a silicon substrate.

10. The true random number generator according to claim 1, wherein: The plurality of magnetic tunnel junctions are arranged such that a distance between two adjacent magnetic tunnel junctions can ensure that no magnetic coupling is generated between the two adjacent magnetic tunnel junctions.

11. A method for generating true random numbers using the true random number generator according to any one of claims 1 to 10, characterized in that: include: Passing the first current through the first electrode and the second electrode, wherein the first current includes a pulse current with a preset interval; At the preset interval, the second current is supplied to the first electrode and the third electrode to measure the magnetic resistance of each magnetic tunnel junction in the plurality of magnetic tunnel junctions, and a random number sequence is obtained according to the magnetic resistance.

12. The method according to claim 11, characterized in that The Joule heat generated by the first current in one pulse period is greater than the energy required for the magnetic moment of the first magnetic layer to be switched.

13. The method according to claim 11, characterized in that The Joule heat generated by the second current within the preset interval is smaller than the energy required for the magnetic moment of the first magnetic layer to be switched.

14. The method according to claim 11, characterized in that Also includes: By controlling the pulse period of the first current, the rate of generating true random numbers is controlled.

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