CN106328805B - Magnetic tunnel-junction with quantum effect and the spin diode and transistor including it - Google Patents
Magnetic tunnel-junction with quantum effect and the spin diode and transistor including it Download PDFInfo
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Abstract
The present invention relates to the magnetic tunnel-junction with quantum effect and including its spin diode and transistor.A kind of magnetic tunnel junction includes: the first reference layer, is formed by magnetic conductive material and has the fixed direction of magnetization；First barrier layer is arranged on first reference layer and is formed by insulating materials；Free layer is arranged on first barrier layer, is formed by magnetic conductive material and its direction of magnetization can freely change in response to external magnetic field；And second barrier layer, it is arranged on the free layer and is formed by insulating materials, wherein the insulating materials of first barrier layer and second barrier layer all has spinel-like crystal structure.
Description
Technical field
Present invention relates in general to magnetic tunnel junction, more specifically it relates to a kind of magnetic tunnel with significant quantum effect
Road knot and spin electric device including the magnetic tunnel junction, such as spin transistor, spin diode, magnetosensitive sensing
Device and oscillator etc..
Background technique
Found tunneling magnetic resistance (TMR) effect and 1988 in magnetic multiplayer in Fe/Ge/Co multilayer film from 1975
It has been found in film since giant magnetoresistance effect (GMR), the research and application of physics and material science in spintronics achieve very
Big progress, the tunneling transmission property of spin correlation electron and Tunneling Magnetoresistance have become cohesion especially in magnetic tunnel junction
One of important research field in state physics.Nineteen ninety-five Miyazaki et al. and Moderola et al. is respectively in feeromagnetic metal/Al-
High room temperature Tunneling Magnetoresistance is had found in O insulative barriers/feeromagnetic metal, has started the research wave of magneto-resistance effect again
Tide.2000, Butler et al. passed through first principle the study found that for monocrystalline MgO (001) barrier magnetic tunnel junction, tunnel
The how sub- electronics of s band (1 symmetry of Δ, spin up) plays a leading role when wearing, available huge tunneling magnetic resistance.This reason
It is experimentally confirmed by the Parkin et al. by Yuasa of Japan et al. and the U.S. in 2004.Currently, people are being based on MgO
(001) the TMR value that room temperature is more than 600% has been obtained in the magnetic tunnel junction of potential barrier.In device application aspect, 1993
Johnson proposes a kind of nonmagnetic metal base stage and iron for being less than spin diffusion length by ferromagnetic metal emitter, thickness
" ferromagnetic metal/nonmagnetic metal/ferromagnetic metal " sandwich all-metal spin transistor of magnetic metal collector composition
Structure (referring to the article Science 260 (1993) 320 of M.Johnson).The speed of this all-metal transistor can with partly lead
Body Si device is compared, but low energy consumption 10-20 times, density is about 50 times high, and radiation hardness, have memory function, can be applied to not
Come various logic circuit, the processor etc. of quantum computer；1994, IBM developed the read head using giant magnetoresistance effect, made
Hard-disc storage density improves 17 times, reaches 3Gbits/in2；2009, Seagate Technology was made using MgO magnetic tunnel junction material
Magnetic head makes hard disc player disk storage density reach 800Gbits/in2。
Currently, people achieve significant achievement in terms of the research of single barrier magnetic tunnel junction, but unipotential tunnel junction barrier
Material also faces many problems in practical applications, sharply declines as TMR value will increase with applied voltage.1997
Zhang et al. has theoretically foretold that the TMR value of the bibarrier tunnel junction with quantizing resonance tunneling effect is that unipotential builds tunnel
2 times of knot, and TMR value relatively slowly (is joined the article Phys.Rev.B56 (1997) of Zhang et al. with the increase decline of bias
5484).And then an important research topic is had become based on the issuable quantum effect of magnetic tunnel junction.Lu in 2005
Et al. using first-principles calculations the prediction of result ferromagnetic metal layer Fe of the magnetic tunnel junction of Fe/MgO/Fe/Cr structure
Spin correlation resonance tunneling effect caused by middle s having electronic quantum well states is (referring to the article of Zhong-Yi Lu et al.
Phys.Rev.Lett.94(2005)207210).2006, Wang et al. had found this be based on using first-principles calculations
The distribution of Quantum Well caused by thickness change in the dual-potential magnetic tunnel of MgO (001) potential barrier with middle layer iron.Together
Year, Nozaki et al. has found tunnel caused by the quantum well states by electronics in intermediate iron layer in this dual-potential magnetic tunnel
Conductance is worn with the oscillation effect of bias.
However, the quantizing resonance tunneling effect of the dual-potential magnetic tunnel based on MgO (001) potential barrier is experimentally not
Obviously, this also counteracts such as spin transistor of the spin electric device based on the quantum effect, spin diode, magnetosensitive sensing
The practical application of device and oscillator etc..Therefore, it is necessary to explore new barrier material, quantum effect is improved to be easy to pass through experiment
It detects, and realizes its practical application in new device.
Summary of the invention
The many and defect faced in practical applications it is an object of the invention to overcome the problems, such as existing barrier material, provides
A kind of magnetic tunnel junction based on spinel-like structural barrier layer, with significant quantum effect.The barrier layer with it is magnetospheric
Lattice mismatch is smaller, can have relatively low bias-dependent, high TMR value, high-breakdown-voltage and the Quantum Well of enhancing
Resonance tunneling effect, so as to be widely used in spin transistor, spin diode, magneto-dependent sensor and oscillator isospin
In electronics device.
An exemplary embodiment according to the present invention provides a kind of magnetic tunnel junction, can include: the first reference layer, by magnetic
Property conductive material formed and there is the fixed direction of magnetization；First barrier layer, be arranged on first reference layer and by
Insulating materials is formed；Free layer is arranged on first barrier layer, is formed by magnetic conductive material and its direction of magnetization can
Freely to change in response to external magnetic field；And second barrier layer, it is arranged on the free layer and is formed by insulating materials,
Wherein, first barrier layer and second barrier layer all have spinel-like crystal structure.
In one example, first barrier layer and second barrier layer are formed by being selected from the material of the following group:
MgxAlyOzAnd ZnxAlyOz, wherein 0≤x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤0.4,0.3≤z/ (x+y+z)≤0.6, and
And x:y:z ≠ 1:2:4.
In one example, first barrier layer and second barrier layer are formed by being selected from the material of the following group:
SixMgyOzAnd SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,0.4 < z/ (x+y+z) < 0.66, and
x:y:z≠1:2:4。
In one example, first barrier layer and second barrier layer have the thickness within the scope of 0.5-5nm.
In one example, the thickness of the free layer can be equal to or less than the mean free path of electronics therein.
In one example, the magnetic tunnel junction may also include that the second reference layer, be arranged on second barrier layer,
It is formed by magnetic material and there is the fixed direction of magnetization.The direction of magnetization of second reference layer can be parallel to described
The direction of magnetization of one reference layer.
In one example, the magnetic tunnel junction may also include that third barrier layer, be arranged on second reference layer,
It is formed by insulating materials, and there is spinel-like crystal structure.
In one example, the third barrier layer is formed by being selected from the material of the following group: MgxAlyOz、ZnxAlyOz, wherein 0
≤ x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤0.4,0.3≤z/ (x+y+z)≤0.6, and x:y:z ≠ 1:2:4；
SixMgyOz、SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,0.4 < z/ (x+y+z) < 0.66, and
x:y:z≠1:2:4。
Another exemplary embodiment according to the present invention provides a kind of magnetic tunnel junction comprising: the first reference layer, by magnetic
Property conductive material formed and there is the fixed direction of magnetization；First barrier layer, be arranged on first reference layer and by
Insulating materials is formed；Free layer is arranged on first barrier layer, is formed by magnetic conductive material and its direction of magnetization can
Freely to change in response to external magnetic field；And second barrier layer, it is arranged on the free layer and is formed by insulating materials,
Wherein, the lattice constant of first barrier layer and first reference layer and the free layer is mutually matched, and wherein, described
The lattice constant of second barrier layer and the free layer is mutually matched.
Another exemplary embodiment according to the present invention provides a kind of spin electric device, may include above-mentioned magnetic tunnel
Any one in knot.
Yet another exemplary embodiment according to the present invention provides a kind of spin diode, can include: the first reference layer, by
Magnetic conductive material forms and has the fixed direction of magnetization；First barrier layer, be arranged on first reference layer and
It is formed by insulating materials；Free layer is arranged on first barrier layer, is formed by magnetic conductive material and its direction of magnetization
It can freely change in response to external magnetic field；Second barrier layer is arranged on the free layer and is formed by insulating materials；The
One electrode is functionally connected to first reference layer；And second electrode, it is functionally connected to the free layer, wherein institute
It states the first barrier layer and second barrier layer all has spinel-like crystal structure.
In one example, first barrier layer and second barrier layer are formed by being selected from the material of the following group:
MgxAlyOzAnd ZnxAlyOz, wherein 0≤x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤0.4,0.3≤z/ (x+y+z)≤0.6, and
And x:y:z ≠ 1:2:4.
In one example, first barrier layer and second barrier layer are formed by being selected from the material of the following group:
SixMgyOzAnd SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,0.4 < z/ (x+y+z) < 0.66, and
x:y:z≠1:2:4。
In one example, the spin diode may also include that the second reference layer, be arranged on second barrier layer,
It is formed by magnetic material and there is the fixed direction of magnetization, wherein the direction of magnetization of second reference layer is parallel to described
The direction of magnetization of first reference layer, and wherein, the second electrode is functionally connected to second reference layer.
In one example, the spin diode may also include that third barrier layer, be arranged on second reference layer,
It is formed by insulating materials, and there is spinel-like crystal structure, wherein the third barrier layer is by selected from the material of the following group
It is formed: MgxAlyOz、ZnxAlyOz, wherein 0≤x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤0.4,0.3≤z/ (x+y+z)≤
0.6, and x:y:z ≠ 1:2:4；SixMgyOz、SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,0.4
< z/ (x+y+z) < 0.66, and x:y:z ≠ 1:2:4.
Another exemplary embodiment according to the present invention provides a kind of spin transistor, can include: the first reference layer, by
Magnetic conductive material forms and has the fixed direction of magnetization；First barrier layer, be arranged on first reference layer and
It is formed by insulating materials；Free layer is arranged on first barrier layer, is formed by magnetic conductive material and its direction of magnetization
It can freely change in response to external magnetic field；Second barrier layer is arranged on the free layer and is formed by insulating materials；The
Two reference layers are arranged on second barrier layer, are formed by magnetic conductive material, and have the fixed direction of magnetization, institute
The direction of magnetization for stating the second reference layer and the direction of magnetization of first reference layer are parallel to each other；Emitter is functionally connected to
First reference layer；Base stage is functionally connected to the free layer；And collector, it is functionally connected to second ginseng
Examine layer, wherein first barrier layer and second barrier layer all have spinel-like crystal structure.
In one example, first barrier layer and second barrier layer are formed by being selected from the material of the following group:
MgxAlyOzAnd ZnxAlyOz, wherein 0≤x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤0.4,0.3≤z/ (x+y+z)≤0.6, and
And x:y:z ≠ 1:2:4.
In one example, first barrier layer and second barrier layer are formed by being selected from the material of the following group:
SixMgyOzAnd SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,0.4 < z/ (x+y+z) < 0.66, and
x:y:z≠1:2:4。
In one example, the spin transistor may also include that third barrier layer, be arranged on second reference layer,
It is formed by insulating materials, and there is spinel-like crystal structure.
In one example, the third barrier layer is formed by being selected from the material of the following group: MgxAlyOz、ZnxAlyOz, wherein 0
≤ x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤0.4,0.3≤z/ (x+y+z)≤0.6, and x:y:z ≠ 1:2:4；
SixMgyOz、SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,0.4 < z/ (x+y+z) < 0.66, and
x:y:z≠1:2:4。
Magnetic tunnel junction provided by the invention based on the insulative barriers layer with spinel-like crystal structure has many
Advantage, such as: the lattice mismatch between barrier layer and magnetosphere is small, and bias-dependent is relatively low, and breakdown voltage is relatively high；Greatly
Reduce the interface in original MgO barrier magnetic tunnel junction and defect electron state greatly, enhance quantum effect, outside certain
Add the electric current and tunneling magnetic resistance ratio (TMR) being greatly improved at threshold values bias through magnetic tunnel junction, threshold values bias
Mainly determined by the selection of magnetospheric material and thickness.This special current effect can also be by among to potential barrier
The externally-applied magnetic field direction of free layer and bias are controlled so that the magnetic tunnel junction of this potential barrier can be applied to it is novel from
Revolve electronic device design, such as spin transistor, spin diode, magneto-dependent sensor and oscillator, and facilitate it is magnetic with
The performance boost of machine memory (MRAM) isospin electronic device.The spin resonance tunneling transistor designed using this structure,
Base current is modulated signal, changes the direction of magnetization of collector by it, to make the signal and base current of collector
Modulating mode it is similar, i.e., generation resonance tunneling effect, under suitable conditions, the signal that can be amplified.Due to this total
The frequency bandwidth of the current amplifier of vibration tunnelling spin transistor production depends on the direction of magnetization speed reversal of collector, thus
Such current amplifier can be changed with the frequency of girz up to a hundred.
Detailed description of the invention
Fig. 1 shows the multilayered structure of typical dual-potential magnetic tunnel；
Fig. 2A and Fig. 2 B schematically shows the energy band diagram of structure shown in Fig. 1；
Fig. 3 shows the quantum effect observed result of dual-potential magnetic tunnel according to an embodiment of the invention；
Fig. 4 schematically shows spin diode according to an embodiment of the invention；
Fig. 5 schematically shows spin diode according to another embodiment of the present invention；
Fig. 6 schematically shows the spin diode of another embodiment according to the present invention；
Fig. 7 schematically shows spin diode according to yet another embodiment of the invention；
Fig. 8 schematically shows the spin diode of another embodiment according to the present invention；
Fig. 9 A and Fig. 9 B show the energy band diagram of spin diode shown in Fig. 8；
Figure 10 schematically shows spin transistor according to an embodiment of the invention；
Figure 11 schematically shows spin transistor according to another embodiment of the present invention；And
Figure 12 schematically shows the spin transistor of another embodiment according to the present invention.
Specific embodiment
Fig. 1 shows the multilayered structure of typical dual-potential magnetic tunnel 100, Fig. 2A and Fig. 2 B schematically shows Fig. 1 institute
The energy band diagram of the dual-potential magnetic tunnel 100 shown.It should be noted that in order to make shown in energy band diagram shown in Fig. 2A and Fig. 2 B and Fig. 1
Multilayered structure it is corresponding, in order to energy band diagram shown in understanding, Fig. 1 is shown double in a manner of laterally stacked rather than be stacked up and down
Multiple layers included by barrier magnetic tunnel junction 100.
Referring to Fig.1, dual-potential magnetic tunnel 100 include the first reference layer 102, the first barrier layer 104, free layer 106,
Second barrier layer 108 and the second reference layer 110.First reference layer 102, free layer 106 and the second reference layer 110 can be by magnetic materials
Material is formed, such as ferrimagnet, semimetal magnetic material and dilute magnetic semiconductor material etc..It can be used to form the first reference layer
102, the example of the ferrimagnet of free layer 106 and the second reference layer 110 includes but is not limited to Fe, Co, Ni or these iron
The alloy of magnetic metal, the rare earth metal of such as Sm, Gd, Nd etc, such as CoFe, CoFeB, NiFeCr, CoFeSiB, GdY and
NiFe (such as Ni81Fe19Deng) etc ferromagnetic alloy.It can be used to form the first reference layer 102, free layer 106 and the second reference
The example of the semimetal magnetic material of layer 110 includes but is not limited to Fe3O4、CrO2、CoMnSi、CoFeAl、CoFeSi、CoMnAl、
CoFeMnAl, CoFeAlSi, CoMnGe, CoMnGa, CoMnGeGa, LaSrMnO, LaGaMnO, NiMnSb, CoMnSb etc..It can use
Include but unlimited in the example for the dilute magnetic semiconductor material for forming the first reference layer 102, free layer 106 and the second reference layer 110
In GaAs, InAs, GaN and ZnTe of Mn doping, ZnO, TiO of Fe, Co, Ni, V, Mn doping2、HfO2And SnO2Deng.First ginseng
Examining layer 102 and each thickness of the second reference layer 110 can be 1-50nm, wherein the thickness of the first reference layer 102 and the second ginseng
The thickness for examining layer 110 can be mutually the same, can also be different from each other.The thickness of free layer 106 can be 0.5-25nm, preferably
Ground, the thickness of free layer 106 are set as suitable with the electron mean free path in the material for forming it.
Each of first reference layer 102 and the second reference layer 110 can have the fixed direction of magnetization, and the magnetic of the two
It is parallel to each other to change direction, shown in the arrow of example as shown in figure 1 straight up.Certainly, the first reference layer 102 and the second reference layer
110 direction of magnetization can also (not shown) straight down.Multiple means can be taken to fix the first reference layer 102 and second
The direction of magnetization of reference layer 110.For example, the can be formed in the side opposite with the first barrier layer 104 of the first reference layer 102
One pinning layer (not shown) carrys out the direction of magnetization that pinning lives the first reference layer 102, and in the second reference layer 110 and the second gesture
The opposite side of barrier layer 108 forms the second pinning layer (not shown) and carrys out the direction of magnetization that pinning lives the second reference layer 110.First nail
Pricking layer and the second pinning layer can each be formed by antiferromagnet, the example of antiferromagnet include but is not limited to Ir, Fe, Rh,
Alloy or CoO, NiO, PtCr of Pt, Pd and Mn etc..First pinning layer and each thickness of the second pinning layer can be 1-
50nm.Alternatively, can make the first reference layer 102 and the second reference layer 110 that there is biggish coercivity, for example, selection coercivity compared with
High material forms the first reference layer 102 and the second reference layer 110, makes the first reference layer 102 and the formation of second reference layer 110
For with biggish thickness, etc..
The direction of magnetization of free layer 106 can be freely, can change with external magnetic field, thus with the first reference layer
102 states parallel or antiparallel with the direction of magnetization of the second reference layer 110, form the high-impedance state of dual-potential magnetic tunnel
(antiparallel) and two kinds of magneto-resistor states of low resistance state (parallel).Free layer 106 is preferably formed by the lesser soft magnetic materials of coercivity,
And there is preferable crystal structure, to guarantee the experimental observation ability of quantum effect.
First barrier layer 104 and the second barrier layer 108 are formed by insulating materials, to form potential barrier.Human hair of the present invention
Existing, the material selection of the first barrier layer 104 and the second barrier layer 108 and crystal structure have significantly quantizing resonance tunneling effect
Influence.The meeting of dual-potential magnetic tunnel 100 shape in the free layer 106 between the first barrier layer 104 and the second barrier layer 108
At s having electronic quantum well states, to generate quantizing resonance tunneling effect.As applying bias V=0, the majority of free layer 106 is certainly
Rotation direction s having electronic (more sons) can be by the primary in the density of states (density of states, DOS) of two-dimentional Brillouin zone point
Principle calculating provides, and there are several spikes in DOS it can be seen that near fermi level, they have respectively corresponded free layer
The quantum well states of how sub- electronics in 106.The level of energy E (unit: electron-volt) of the quantum well states nearest from fermi level
Correspond to the bias threshold values size (unit: volt) for generating quantum effect.These quantum well states are total to dual-potential magnetic tunnel
Quantum effect caused by tunnelling of shaking can be in electric current with the I-V curve and tunnel knot tunneling magnetic resistance (TMR) of bias relation
Find out in value and the relationship of bias.
Free layer 106 and the first reference layer 102 and the second ginseng between the first barrier layer 104 and the second barrier layer 108
Examine layer 110 the direction of magnetization it is parallel to each other when, the quantum well states of the more sons of s band in free layer 106 will affect dual-potential magnetic tunnel
The transport property of road knot 100.As applying bias V=0, the fermi level E of the electronics in the first reference layer 102FFar from freely
The level of energy E of the how sub- electronics of s band in layer 106, does not occur resonance tunnel-through, as shown in fig. 2 at this time.When applying bias V by
It is cumulative when being added to a threshold values biased position, so that fermi level EFThe level of energy E of neighbouring how sub- quantum well states is entered
Within bias range, as shown in Figure 2 B.At this point, the electron energy level transported in electronics and trap in the first reference layer 102 resonates, trap
The middle how sub- electronic state of s band participates in transport process by quantum Interference, will make to have by the electric current of bibarrier tunnel junction at this time
It jumps by a relatively large margin.Since the quantum well states of the electronics in free layer 106 are spin correlation (how sub- quantum well states), so only
This quantum effect occurs under parallel condition.When by change externally-applied magnetic field make free layer 106 with first and second ginsengs
Examine layer 102,110 the direction of magnetization it is antiparallel when, be not present this quantum effect.Therefore this quantum that free layer 106 generates
The direction of magnetization that resonance tunneling effect can control free layer 106 by externally-applied magnetic field carries out ON/OFF control.
Moreover, the quantum well states E of free layer 106 is relative to fermi level EFPosition depend primarily on the first He of two sides
The material of second reference layer 102,110 and the thickness of free layer 106.Therefore, if having selected the first and second reference layers 102,
110 material, then the fermi level of entire magnetic tunnel junction is fixed, then i.e. controllable by the thickness for changing free layer 106
Generate the threshold values bias value of this quantum effect.
Although theoretically having foretold the presence of quantizing resonance tunneling effect, do not observe always experimentally significant
Quantizing resonance tunneling effect.As previously mentioned, the inventors discovered that, in order to realize experimentally observable quantum effect, in addition to
Free layer 106 should have except good crystal structure, first barrier layer 104 adjacent with free layer 106 and the second barrier layer
108 material selection and crystal structure are also particularly significant.In an exemplary embodiment of the invention, the first barrier layer 104 and
The material of two barrier layers 108 can be selected from MgxAlyOzAnd ZnxAlyOz, wherein 0≤x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤
0.4,0.3≤z/ (x+y+z)≤0.6, and x:y:z ≠ 1:2:4.The material of first barrier layer 104 and the second barrier layer 108 is also
It can be selected from SixMgyOzAnd SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,0.4 < z/ (x+y+z) <
0.66, and x:y:z ≠ 1:2:4.Preferably, the first barrier layer 104 and the second barrier layer 108 all have spinel-like crystal knot
Structure.
Experimentally it has been found that MgO monocrystalline is imitated as the quantizing resonance tunnelling in the dual-potential magnetic tunnel of barrier layer
It should be not obvious, there is the Mg of perfect spinel crystal structurexAlyOz、ZnxAlyOz、SixMgyOzAnd SixZnyOz(wherein x:y:z
=1:2:4) be used as barrier layer when, quantizing resonance tunneling effect is also unobvious.However the inventors discovered that, when using with class point
When the oxide-insulator of spar crystal structure is as abarrier layer material, significant quantum effect may be implemented." class point is brilliant for term
Stone " refers to such a crystal structure, close with spinel crystal structure, but due to the ratio between element and accounts for
Position is different from the elemental ratio 1:2:4 in perfect spinel structure, so not being perfect spinel crystal structure again.In class point
In spar crystal structure, due to the variation of component ratio, position of each element in lattice is unlike perfect spinel crystal structure
In it is so orderly and fixed, but a degree of unordered and randomness may be shown, such as should in certain structure cell Central Plains
The position occupied by elements A is but occupied by element B.Moreover, because the difference of component ratio, some positions, such as, but not limited to
The position of oxygen element, it is possible that vacancy.Therefore, although spinel-like structural refer to generally with spinel structure phase
Seemingly, but in detail the crystal structure of certain random difference is presented again.Experiment discovery, for typical material MgxAlyOz、
ZnxAlyOz、SixMgyOzAnd SixZnyOzFor, as component ratio x:y:z=1:2:4, form perfect spinel crystal
Structure, but quantum effect is not obvious when being used as barrier layer；And when x:y:z is not equal to 1:2:4, it is formed and is similar to point crystalline substance
" spinel-like " crystal structure of stone, quantum effect will become obvious at this time.Further analysis shows, this is Lattice Matching institute
Bring effect.The lattice constant of MgO monocrystalline and spinel structure, which is typically greater than, forms adjacent reference layer or free layer
The lattice constant of magnetic material, therefore its interface lattice mismatch is larger, there are more interfacial states and defect electron state.At this point,
Even if meeting resonance tunnel-through condition, since resonance tunnel-through is mainly participated in by the how sub- electronics of s band, and the how sub- electronics of s band is easy to
Interface is scattered, so tunnelling current is small, quantum effect is not significant.And " spinel-like " crystal structure can provide with it is adjacent
First and second reference layers 102,110 and the more matched lattice constant of free layer 106, to greatly reduce interface state density
With defect electron state so that resonant tunnel current is less scattered in interface, thus realize it is more significant, can experimentally hold
It changes places the quantizing resonance tunneling effect of observation.Experimentally it has also been found that, the Al of γ phase2O3Monocrystalline also has spinel-like crystal knot
Structure is also able to achieve significant quantum effect when being used as potential barrier.
Therefore, in an embodiment of the present invention, forming the first barrier layer 104 and the material of the second barrier layer 108 can be selected from:
MgxAlyOzAnd ZnxAlyOz, wherein 0≤x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤0.4,0.3≤z/ (x+y+z)≤0.6, and
And x:y:z ≠ 1:2:4；SixMgyOzAnd SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,0.4 < z/ (x
+ y+z) < 0.66, and x:y:z ≠ 1:2:4.In above-mentioned chemical formula, x+y+1 can be equal to 1.And preferably, the first potential barrier
Layer 104 and the second barrier layer 108 are all formed as spinel-like crystal structure, have more significant quantizing resonance tunnelling to realize
The dual-potential magnetic tunnel 100 of effect.First barrier layer 104 and each thickness of the second barrier layer 108 can be 0.5-
5nm, preferably 1-4nm.The material of first barrier layer 104 and the second barrier layer 108 can be mutually the same, can also be different from each other.
Moreover, the thickness of the first barrier layer 104 and the second barrier layer 108 can be mutually the same, it can also be different from each other.
Following table 1 shows some specific examples and comparative example of dual-potential magnetic tunnel 100, and experimentally quantum
The observed result of effect.Although it is not shown, these examples are formed on SiO2On substrate, but not limited to this, such as can also be with
It is formed in other insulating substrates.Wherein, for simplicity the first reference layer 102 and the second reference layer 110 are by identical material
Material is formed as identical thickness, and the first barrier layer 104 and the second barrier layer 108 are formed from the same material as identical thickness.
It should be understood that the material and/or thickness of the first reference layer 102 can be different from the second reference layer, the first barrier layer 104
Material and/or thickness can be different from the second barrier layer 108.
Table 1
It should be understood that first and second barrier layers 104,108 are formed as perfect spinelle in comparative example 2 and 3 above
Crystal structure, quantum effect are unobvious.Although in the embodiment listed by table 1 above, the first barrier layer 104 and the second gesture
Barrier layer 108 is manufactured from the same material, but the first barrier layer 104 and the second barrier layer 108 can also be made from a variety of materials,
Embodiment as shown in Table 2 below.
Table 2
Fig. 3 shows an exemplary quantum effect experimental observations of the invention.As shown in figure 3, in bias voltage V appropriate
In range, the second dervative of I/V, i.e. d2I/dV2, there is apparent fluctuation, each wave crest corresponds to one in free layer 106
A quantum well states.This shows to observed apparent quantizing resonance tunneling effect in the structure of the present invention.
It can although experiment can be obtained described above is magnetic tunnel junction made of the barrier layer based on spinel-like structural
The quantum effect of observation, but the present invention is not limited thereto.As previously mentioned, when the interface tool between barrier layer and adjacent magnetic layer
When having good Lattice Matching, interfacial state can be reduced, avoids the scattering of spinning electron, to realize significant quantum effect.
Therefore, barrier layer of the invention is not limited to spinel-like structural, as long as but its lattice constant magnetosphere (example adjacent thereto
Such as reference layer and free layer) lattice constant match.
Described above is the typical structures of dual-potential magnetic tunnel 100.It will be appreciated, however, by one skilled in the art that may be used also
To carry out many variations to the structure.For example, the second reference layer 110 can be omitted.At this point, current path is from the first reference
Layer 102, to free layer 106, is then brought out through the first barrier layer 104.The second reference layer 110 is omitted even if should be noted that, second
Barrier layer 108 should be also retained, because itself and the first barrier layer 104 are together for forming Quantum Well in free layer 106.Or
Person, it is convenient to omit the first reference layer 102, current path are from the second reference layer 110 through the second barrier layer 108 to free layer 106,
Then it is brought out.Although further, it should be appreciated that with the ordinal numbers such as " first ", " second " describe each layer above,
These ordinal numbers are only used for distinguishing a layer with another layer, and do not limit their any sequence.In other words, it retouches above
" first " layer stated also can be described as " second " layer, without departing from the scope of the present invention.
It describes to include above-mentioned class magnetic tunnel junction (dual-potential magnetic tunnel as described above below with reference to accompanying drawings
Knot 100) various spin electric devices embodiment.
Fig. 4 shows the spin diode 200 including dual-potential magnetic tunnel.As shown in figure 4, spin diode 200 is
Double potential barrier pinning type magnetic tunnel junction resonance tunnel-through diode comprising the laminated construction being formed on substrate 202.Substrate 202
It can be insulator substrates, for example including selected from the material such as the following group: Si/SiO2、MgO、GaAs、SrTiO3、LaAlO3And
MgAl2O4Deng.Buffer layer 204, the first pinning layer 206, the first reference layer 102, the first barrier layer are sequentially formed on substrate 202
104, free layer 106, the second barrier layer 108, the second reference layer 110, the second pinning layer 208 and cap rock 210.
Buffer layer 204 can be made of metal or alloy, such as Cr, CoFe, Ta, Ru etc., can have between 5-100nm
Thickness.Buffer layer 204 is used to improve between the first pinning layer 206 and substrate 202 thereon and adhesiveness, provides good be used for
Deposit the surface of the first pinning layer 206.In some embodiments, buffer layer 204 can omit.The reference of first pinning layer 206, first
The 102, first barrier layer 104 of layer, free layer 106, the second barrier layer 108, the second reference layer 110 and the second pinning layer 208 are
It is discussed in detail above in relation to Fig. 1, details are not described herein again.Cap rock 210 can by it is corrosion-resistant and have satisfactory electrical conductivity
Metal formed, such as Ta, Au etc., to protect following multilayered structure.First reference layer 102 may be coupled to first electrode
101, cap rock 210 may be coupled to second electrode 201.It should be understood that first electrode 101 can also be connected to buffer layer 204 or the
One pinning layer 206, second electrode 201 can also be connected to the second pinning layer 208 or the second reference layer 110.Here it is possible to say
One electrode 101 is functionally connected to the first reference layer 102, and second electrode 201 is functionally connected to the second reference layer 110." function
Upper connection " refers to realize circuit function and must connect electrode (direct or indirect) to a certain layer, such as the first ginseng
Examine layer 102 and the second reference layer 110.In some embodiments, since the second pinning layer 208 itself has good corrosion resistance
And electric conductivity, so cap rock 210 also can be omitted.
Illustrate the method for preparation spin diode 200 below.Can use magnetron sputtering apparatus deposit it is shown in Fig. 4 from
Revolve diode 200.When deposition, add the plane induced magnetic field of 1000Oe, therefore the first reference layer 102 and the second reference layer 110
The direction of magnetization is fixed into same direction by the first pinning layer 206 and the second pinning layer 208 respectively, and the magnetization side of free layer 106
To being free.It selects for example with a thickness of the MgO of 0.5mm (001) substrate as substrate, and with vacuum on magnetron sputtering apparatus
Better than 5 × 10-7Pa, deposition rate 0.1nm/s, Ar Pressure is 0.07 pa when deposition, deposited on substrate 202 Cr (40nm)/
The buffer layer 204 of CoFe (5nm) can carry out thermal anneal process to form better crystal orientation and flatness after deposition；Then
The IrMn with a thickness of 15nm is sequentially depositing on buffer layer 204 as the first pinning layer 206, deposition thickness is the of the Fe of 5nm
One reference layer 102, deposition thickness are the Mg of 2nm0.29Al0.23O0.48(001) it is used as the first barrier layer 104, the Fe for depositing 5nm makees
For free layer 106, deposition thickness is the Mg of 2nm0.29Al0.23O0.48(001) it is used as the second barrier layer 108, the Fe for depositing 5nm makees
For the second reference layer 110, the IrMn that deposition thickness is 15nm finally deposits Ta (5nm)/Ru (5nm) as the second pinning layer 208
As cap rock 210.The growth conditions of above-mentioned multilayer film is as follows: standby bottom vacuum: 5 × 10-7Pa；Sputtering high purity argon air pressure:
0.07 pa；Sputtering power: 120 watts；Growth temperature: room temperature；Growth rate: 0.3~1.1 angstroms per second；Growth time: film thickness/
Growth rate.
Then micro fabrication is utilized, prepares the tunnel junction diode of micron-scale, and build and be used on interface
The electrode of measurement.(1) it is coated on the magnetic multiplayer membrane sample deposited positive photoresist (S1813), 4000 turns/min of spin coating,
Time 1 minute, about 1 micron of glue thickness, 95 degrees Celsius lower front baking 1 minute, then utilize the mask plate of hearth electrode, it is purple to carry out contact
Outer exposure, generally 15-20 second；Development 30 seconds is carried out using developer solution MF319, is fixed 30 seconds in ultrapure water, it is rear to dry 1 point
Clock；Sample is put into Ar ion etching machine, Ar ion etching is carried out, obtains the shape of hearth electrode, etch period by marking in advance
The thickness of the etch rate and multilayer film set determines；Sample is put into acetone and removes remaining photoresist.(2) again in shape
Photoresist is coated at the sample surfaces of hearth electrode, in order to reduce the difficulty of subsequent lift-off (lift-off) technique, selects minus light
Photoresist (N440), 4000 turns/min of spin coating, the time 1 minute, about 4 microns of glue thickness, 90 degrees Celsius lower front baking 5 minutes.Recycle knot
The mask plate in area is exposed 200 seconds, is developed 2 minutes or so in developer solution D332, until the decorative pattern of sample surfaces glue dissipates
It goes, is fixed 30 seconds；Ar ion etching is finally carried out, the first barrier layer 104 was carved, and obtained the shape in interface.(3) magnetic is utilized
Sputtering sedimentation is controlled with a thickness of the SiO of 100nm or so2, top for making interface mutually insulated and hearth electrode 101 with depositing
201 mutual insulating of electrode；Lift-off method (lift-off) is carried out again, sample is put into acetone or glue-dispenser, ultrasonic depolymerization, covering
Cover photoresist and SiO on interface2It removes together, makes interface exposure.(4) deposited on sample about 80nm thickness Cu and
The Au of 20nm thickness coats positive photoresist (S1813) in sample surfaces again, utilizes the mask plate of top electrode as top electrode layer
It is exposed, developing fixing (front baking and time for exposure same hearth electrode)；Ar ion etching is carried out again, to obtain magnetic tunnel junction
200 top electrode 201, sample is put into acetone, removes residue glue.There is magnetic tunnel junction and additional with regard to what this was prepared
Measure the unit of hearth electrode 101 and top electrode 201.Obtain double potential barrier pinning type magnetic tunnel junction spin resonance tunnel of the invention
Wear diode 200.
It should be understood that many details, including material and parameter etc. have been used when describing manufacturing process above, this merely to
Make those skilled in the art present invention convenient to carry out, and the invention is not limited to these specific details.On the contrary, thin for these
Section, material and parameter etc., those skilled in the art can carry out various change under the teachings of the present invention, without departing from
The scope of the present invention.
When externally-applied magnetic field keeps free layer 106 parallel with the direction of magnetization of the first and second reference layers 102,110, free layer
The quantum well states of the more sons of s band in 106 Fe will affect the transport property of bibarrier tunnel junction.When applying bias V increases to valve
When being worth biased position (about 0.1~0.3 volt), the electron energy level transported in tunelling electrons and Quantum Well resonates, and will make to lead at this time
The electric current for crossing bibarrier tunnel junction has to jump by a relatively large margin.
Fig. 5 shows the non-pinning type magnetic tunnel junction resonance tunnel-through diode 300 of double potential barrier according to an embodiment of the invention.
As shown in figure 5, the non-pinning type magnetic tunnel junction resonance tunnel-through diode 300 of double potential barrier and double potential barrier pinning type magnetic shown in Fig. 4
Property tunnel junction resonance tunneling diode 200 there is basically same structure, in addition to omitting the first pinning layer 206 and the second pinning layer
Except 208.It, can be using with larger coercive in order to fix the first reference layer 102 and the direction of magnetization of the second reference layer 110
The magnetic material of power forms them, or forms it into biggish thickness.In addition, in deposition 102 He of the first reference layer
When the second reference layer 110, the plane induced magnetic field of such as 100Oe can be applied, be induced their direction of magnetization described
On direction.Other aspects and 200 phase of magnetic tunnel junction resonance tunnel-through diode of magnetic tunnel junction resonance tunnel-through diode 300
Together, details are not described herein again.
Although will also be appreciated that above two design can be with described above is pinning design and the design of non-pinning
Neatly mixing setting.For example, a reference layer can be designed using pinning, and another reference layer can be set using non-pinning
Meter is also referred to as designed from pinning.This can be by those skilled in the art according to actual needs with technique convenience come flexible choice.
Fig. 6 shows double potential barrier pinning type magnetic tunnel junction resonance tunnel-through diode 400 according to an embodiment of the invention.Such as
Shown in Fig. 6, double potential barrier pinning type magnetic tunnel junction resonance tunnel-through diode 400 has and double potential barrier pinning type magnetic shown in Fig. 4
Property the identical structure of tunnel junction resonance tunneling diode 200, other than hearth electrode 401 is arranged on free layer 106.Accordingly
Ground, above in relation in the interface etching step (2) of Fig. 4 description, it is only necessary to etched second barrier layer 108, without
Etched first barrier layer 104 as diode 200.Other aspects of diode 400 are similar with diode 200, herein not
It repeats again.
It should be understood that first barrier layer 104 is used for and the second barrier layer 108 1 in diode 400 shown in Fig. 6
It rises and forms Quantum Well in free layer 106, and the first barrier layer 104 is not engaged in electron transport in itself.It is also understood that
, the first reference layer 102, the first pinning layer 206 and the buffer layer 204 of the lower section of the first barrier layer 104 can be omitted.
Fig. 7 shows the non-pinning type magnetic tunnel junction resonance tunnel-through diode 500 of double potential barrier according to an embodiment of the invention.
As shown in fig. 7, the non-pinning type magnetic tunnel junction resonance tunnel-through diode 500 of double potential barrier has and the non-nail of double potential barrier shown in fig. 5
The identical structure of bundle type magnetic tunnel junction resonance tunnel-through diode 300, other than hearth electrode 501 is arranged on free layer 106.
Correspondingly, above in relation in the interface etching step (2) of Fig. 5 (in other words, Fig. 4) description, it is only necessary to etched second potential barrier
Layer 108, without first barrier layer 104 etched as diode 300.Other aspects of diode 500 and two poles
Pipe 300 is similar, and details are not described herein again.
It should be understood that first barrier layer 104 is used for and the second barrier layer 108 1 in diode 500 shown in Fig. 7
It rises and forms Quantum Well in free layer 106, and the first barrier layer 104 is not engaged in electron transport in itself.It is also understood that
, the first reference layer 102 and buffer layer 204 of the lower section of the first barrier layer 104 can be omitted.
Fig. 8 shows the non-pinning type magnetic tunnel junction resonance tunnel-through diode 600 of three potential barrier according to an embodiment of the invention.
As shown in figure 8, the non-pinning type magnetic tunnel junction resonance tunnel-through diode 600 of three potential barriers has and the non-nail of double potential barrier shown in fig. 5
The identical structure of bundle type magnetic tunnel junction resonance tunnel-through diode 300, in addition to third barrier layer 602 is formed in the first reference layer
Other than between 102 and substrate 202.Preferably, the material for forming third barrier layer 602, which is also selected from, above-mentioned can be used to form the first gesture
Those of barrier layer 104 and the second barrier layer 108 material, in order to the first barrier layer 104 together shape in the first reference layer 102
At good Quantum Well.Due to third barrier layer 602 and it is not involved in electron transport, so generally also there is no limit examples for its thickness
It such as can be formed thicker.Preferably, the thickness of third barrier layer 602 can be 0.5nm or more.In addition, third barrier layer 602
It can also play the role of buffer layer, provide good deposition surface for the first reference layer 102 thereon.The formation of diode 600
Technique can be similar with diode 300, and details are not described herein again.
Fig. 9 A and 9B show the energy band diagram of schematic diode 600, and wherein Fig. 9 A shows feelings when bias voltage V is zero
Condition, Fig. 9 B shows that bias voltage V reaches threshold voltage and there is a situation where when resonance tunnel-through.As shown in Figure 9 A, as applying bias V
When=0, the level of energy E of the quantum well states of the electronics in the first reference layer 1021Far from the how sub- electronics of s band in free layer 106
Level of energy E2, resonance tunnel-through does not occur at this time.When applying bias V progressively increases to threshold values bias E2-E1Level when, make
Obtain the level of energy (V+E in the first reference layer 1021) enter near the energy level in free layer 106, the first reference at this time
Electron energy level in the Quantum Well of the electronics and free layer 106 in Quantum Well in layer 102 resonates, and is joined by quantum Interference
With into transport process, will make to have by the electric current of tunnel knot at this time to jump by a relatively large margin.
Figure 10 shows double potential barrier pinning type magnetic tunnel junction resonant tunneling thin film 700 according to an embodiment of the invention.
As shown in fig. 7, magnetic tunnel junction resonant tunneling thin film 700 has and magnetic tunnel junction resonance tunnel-through diode shown in Fig. 4
200 identical structures, other than third electrode 701 is also connected to free layer 106.In magnetic tunnel junction resonance tunnel-through crystal
In pipe 700, first electrode 101 can be used as emitter, and second electrode 201 can be used as collector, and third electrode 701 can be used as base
Pole.
The magnetic of free layer 106, the first reference layer 102 and the second reference layer 110 locating for base stage, the emitter and collector
When change direction is in parastate, the quantum well states of the more sons of s band in free layer 106 will affect the transport property of bibarrier tunnel junction
Matter.It is defeated when being biased V between emitter and collector increases to threshold values biased position (generally about 0.1~0.3 volt)
The electron energy level transported in tunelling electrons and Quantum Well resonates, and will make to have by the collector current of bibarrier tunnel junction at this time larger
Amplitude jumps.And when the direction of magnetization of base stage is opposite with the direction of magnetization of collector, although most spin subbands in emitter
Electronics since mutually energy band mismatches the direction of magnetization with base stage instead, by strong scattering process, only seldom tunnelling electricity
Son is due to being entered collector, at this time the electric current very little of collector by impurity scattering or other effects.Further, when base stage,
Free layer 106 locating for emitter and collector, the first reference layer 102 and the direction of magnetization of the second reference layer 110 are in parallel
When state, the height of Quantum Well energy level in base stage can be modulated by the method for the voltage/current of change base stage, to make tunnel
It wears electronics and resonance tunnel-through occurs between emitter and collector, the electric current for amplifying collector.
Magnetic tunnel junction resonant tunneling thin film 700 is prepared using the method for magnetron sputtering.When deposition, add 1000Oe's
Plane induced magnetic field, therefore the direction of magnetization of the first reference layer 102 and the second reference layer 110 is respectively by 206 He of the first pinning layer
Second pinning layer 208 is fixed into same direction, and the direction of magnetization of free layer 106 is free.Selection one is with a thickness of 0.5mm's
MgO (001) substrate is better than 5 × 10 as substrate, and on magnetron sputtering apparatus with vacuum-7Pa, deposition rate 0.1nm/s,
Ar Pressure is 0.07 pa when deposition, deposits the buffer layer 204 of Cr (40nm)/CoFe (5nm) over the substrate, can be into after deposition
Row thermal anneal process forms better crystal orientation and flatness；Then it is sequentially depositing on buffer layer 204 with a thickness of 15nm's
For IrMn as the first pinning layer 206, deposition thickness is the first reference layer 102 of the Fe of 5nm, and deposition thickness is 2nm's
Mg0.29Al0.23O0.48(001) it is used as the first barrier layer 104, deposits the Fe of 5nm as free layer 106, deposition thickness is 2nm's
Mg0.29Al0.23O0.48(001) it is used as the second barrier layer 108, deposits the Fe of 5nm as the second reference layer 110, deposition thickness is
The IrMn of 15nm finally deposits Ta (5nm)/Ru (5nm) and is used as cap rock 210 as the second pinning layer 208.The life of above-mentioned multilayer film
Elongate member: standby bottom vacuum: 5 × 10-7Pa；Sputtering high purity argon air pressure: 0.07 pa；Sputtering power: 120 watts；Growth temperature:
Room temperature；Growth rate: 0.3~1.1 angstroms per second；Growth time: film thickness/growth rate.
Then micro fabrication is utilized, prepares the tunnel junction transistor of micron-scale, and build and be used on interface
Emitter, base stage and the collector of measurement.(1) it is coated on the magnetic multiplayer membrane sample deposited positive photoresist (S1813),
4000 turns/min of spin coating, the time 1 minute, about 1 micron of glue thickness, 95 degrees Celsius front baking 1 minute, then utilize hearth electrode mask
Plate, progress contact uv-exposure, generally 15-20 seconds；Development 30 seconds is carried out using developer solution MF319, then fixed with ultrapure water
It is shadow 30 seconds, rear to dry 1 minute；Sample is put into Ar ion etching machine, Ar ion etching is carried out, obtains hearth electrode (emitter)
Shape, etch period are determined by the thickness of the etch rate and multilayer film demarcated in advance；Sample is put into acetone and is removed
Remaining photoresist.(2) photoresist is coated in the sample surfaces for forming hearth electrode again, in order to reduce subsequent lift-off (lift-off)
The difficulty of technique is selected negative photoresist (N440), 4000 turns/min of spin coating, the time 1 minute, about 4 microns of glue thickness, 90 degrees Celsius
Front baking 5 minutes.The mask plate for recycling interface, is exposed 200 seconds, develops 2 minutes or so in developer solution D332, until sample
The decorative pattern of surface glue disperses, and is fixed 30 seconds；Ar ion etching is finally carried out, the first barrier layer 104 was carved, and obtained interface
Shape.(3) SiO for being 100nm or so using magnetron sputtering deposition thickness2, for make interface mutually insulated and hearth electrode with
By the top electrode mutual insulating of deposition；Metal liftoff method (lift-off) is carried out again, sample is put into acetone or glue-dispenser, is surpassed
Sound removes photoresist, the photoresist and SiO being covered on interface2It removes together, makes interface exposure.(4) it further repeats above
The micro-nano processing technologys such as gluing, exposure, development, etching, lift-off and deposition, prepare base stage and collector.Obtain double gesture
Build pinning type magnetic tunnel junction spin resonance tunnelling crystalline substance pole pipe 700.
Figure 11 shows the non-pinning type magnetic tunnel junction resonance tunnel-through crystalline substance pole pipe of double potential barrier according to an embodiment of the invention
800.As shown in figure 11, the non-pinning type magnetic tunnel junction resonance tunnel-through crystalline substance pole pipe 800 of double potential barrier has and double potential barrier pinning type magnetic
The identical multilayered structure of property tunnel knot spin resonance tunnelling crystalline substance pole pipe 700, in addition to not including the first pinning layer 206 and the second pinning
Except layer 208.It, can be larger strong using having in order to fix the first reference layer 102 and the direction of magnetization of the second reference layer 110
The magnetic material of stupid power forms them, or forms it into biggish thickness.In addition, depositing the first reference layer 102
When with the second reference layer 110, the plane induced magnetic field of such as 1000Oe can be applied, be induced their direction of magnetization in institute
It states on direction.Other aspects of the non-pinning type magnetic tunnel junction resonance tunnel-through crystalline substance pole pipe 800 of double potential barrier can be with double potential barrier pinning
Type magnetic tunnel junction spin resonance tunnelling crystalline substance pole pipe 700 is identical, and details are not described herein again.
Figure 12 shows the non-pinning type magnetic tunnel junction resonance tunnel-through crystalline substance pole pipe of three potential barrier according to an embodiment of the invention
900.As shown in figure 12, the non-pinning type magnetic tunnel junction resonant tunneling thin film 900 of three potential barriers has and double gesture shown in Figure 11
The identical structure of non-pinning type magnetic tunnel junction resonant tunneling thin film 800 is built, in addition to third barrier layer 902 is formed in the first ginseng
Other than examining between layer 102 and substrate 202.Preferably, the material for being used to form third barrier layer 902 can be selected from above-mentioned for shape
At those of the first barrier layer 104 and the second barrier layer 108 material.Electronics actually and is not involved in due to third barrier layer 902
It transports, so the typically no limitation of its thickness, such as can be formed thicker.Preferably, the thickness of third barrier layer 902 can be with
For 0.5nm or more.In addition, third barrier layer 902 can also play the role of buffer layer, provided for the first reference layer 102 thereon
Good deposition surface.The formation process of transistor 900 can be similar with transistor 800, and details are not described herein again.
Magnetic tunnel junction provided by the invention based on the insulative barriers layer with spinel-like crystal structure has many
Advantage, such as: the lattice mismatch between barrier layer and magnetosphere is small, and bias-dependent is relatively low, and breakdown voltage is relatively high；Greatly
Reduce the interface in original MgO barrier magnetic tunnel junction and defect electron state greatly, enhance quantum effect, outside certain
Add the electric current and tunneling magnetic resistance ratio (TMR) being greatly improved at threshold values bias through magnetic tunnel junction, threshold values bias
Mainly determined by the selection of magnetospheric material and thickness.This special current effect can also be by among to potential barrier
The externally-applied magnetic field direction of free layer and bias are controlled so that the magnetic tunnel junction of this potential barrier can be applied to it is novel from
Revolve electronic device design, such as spin transistor, spin diode, magneto-dependent sensor and oscillator, and facilitate it is magnetic with
The performance boost of machine memory (MRAM) isospin electronic device.The spin resonance tunneling transistor designed using this structure,
Base current is modulated signal, by changing the direction of magnetization of base stage, to make the signal of collector and the tune of base current
Molding formula is similar, i.e. generation resonance tunneling effect, under suitable conditions, the signal that can be amplified.Due to this resonance tunnel
The frequency bandwidth for wearing the current amplifier of spin transistor production depends on the direction of magnetization speed reversal of collector, thus in this way
Current amplifier can be changed with the frequency of girz up to a hundred.
Although describing the present invention above with reference to exemplary embodiment, but the invention is not restricted to this.Those skilled in the art
Member can carry out in form and details various it is readily apparent that in the case where not departing from the scope of the present invention and thought
Change and modification.The scope of the present invention is only defined by appended claims and its equivalent.
Claims (20)
1. a kind of magnetic tunnel junction, comprising:
First reference layer is formed by magnetic conductive material and has the fixed direction of magnetization；
First barrier layer is arranged on first reference layer and is formed by insulating materials；
Free layer is arranged on first barrier layer, is formed by magnetic conductive material and its direction of magnetization can be in response to
External magnetic field and freely change；And
Second barrier layer is arranged on the free layer and is formed by insulating materials,
Wherein, the insulating materials of first barrier layer and second barrier layer all has spinel-like crystal structure.
2. magnetic tunnel junction as described in claim 1, wherein first barrier layer and second barrier layer by selected from
The material of the following group is formed: MgxAlyOzAnd ZnxAlyOz, wherein 0≤x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤0.4,0.3≤z/
, and x:y:z ≠ 1:2:4 (x+y+z)≤0.6.
3. magnetic tunnel junction as described in claim 1, wherein first barrier layer and second barrier layer by selected from
The material of the following group is formed: SixMgyOzAnd SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,0.4 < z/ (x
+ y+z) < 0.66, and x:y:z ≠ 1:2:4.
4. magnetic tunnel junction as described in claim 1, wherein first barrier layer and second barrier layer each have
Thickness within the scope of 0.5-5nm.
5. magnetic tunnel junction as described in claim 1, further includes:
Second reference layer is arranged on second barrier layer, is formed by magnetic material and has the fixed direction of magnetization.
6. magnetic tunnel junction as claimed in claim 5, wherein the direction of magnetization of second reference layer is parallel to described first
The direction of magnetization of reference layer.
7. magnetic tunnel junction as claimed in claim 5, further includes:
Third barrier layer is arranged on second reference layer, is formed by insulating materials, and has spinel-like crystal knot
Structure.
8. magnetic tunnel junction as claimed in claim 7, wherein the third barrier layer is formed by being selected from the material of the following group:
MgxAlyOz、ZnxAlyOz, wherein 0≤x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤0.4,0.3≤z/ (x+y+z)≤
0.6, and x:y:z ≠ 1:2:4；
SixMgyOz、SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,0.4 < z/ (x+y+z) < 0.66,
And x:y:z ≠ 1:2:4.
9. a kind of magnetic tunnel junction, comprising:
First reference layer is formed by magnetic conductive material and has the fixed direction of magnetization；
First barrier layer is arranged on first reference layer and is formed by insulating materials；
Free layer is arranged on first barrier layer, is formed by magnetic conductive material and its direction of magnetization can be in response to
External magnetic field and freely change；And
Second barrier layer is arranged on the free layer and is formed by insulating materials,
Wherein, the lattice constant of first barrier layer and first reference layer and the free layer is mutually matched, and
Wherein, the lattice constant of second barrier layer and the free layer is mutually matched.
10. a kind of spintronics devices, including the magnetic tunnel junction as described in any one in claim 1-9.
11. a kind of spin diode, comprising:
First reference layer is formed by magnetic conductive material and has the fixed direction of magnetization；
First barrier layer is arranged on first reference layer and is formed by insulating materials；
Free layer is arranged on first barrier layer, is formed by magnetic conductive material and its direction of magnetization can be in response to
External magnetic field and freely change；
Second barrier layer is arranged on the free layer and is formed by insulating materials；
First electrode is functionally connected to first reference layer；And
Second electrode is functionally connected to the free layer,
Wherein, first barrier layer and second barrier layer all have spinel-like crystal structure.
12. spin diode as claimed in claim 11, wherein first barrier layer and second barrier layer are by being selected from
It is formed with the material of the following group: MgxAlyOzAnd ZnxAlyOz, wherein 0≤x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤0.4,0.3≤
Z/ (x+y+z)≤0.6, and x:y:z ≠ 1:2:4.
13. spin diode as claimed in claim 11, wherein first barrier layer and second barrier layer are by being selected from
It is formed with the material of the following group: SixMgyOzAnd SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,0.4 < z/
, and x:y:z ≠ 1:2:4 (x+y+z) < 0.66.
14. spin diode as claimed in claim 11, further includes:
Second reference layer is arranged on second barrier layer, is formed by magnetic material and had the fixed direction of magnetization,
Wherein, the direction of magnetization of second reference layer is parallel to the direction of magnetization of first reference layer, and
Wherein, the second electrode is functionally connected to second reference layer.
15. spin diode as claimed in claim 14, further includes:
Third barrier layer is arranged on second reference layer, is formed by insulating materials, and has spinel-like crystal knot
Structure,
Wherein, the third barrier layer is formed by being selected from the material of the following group:
MgxAlyOz、ZnxAlyOz, wherein 0≤x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤0.4,
0.3≤z/ (x+y+z)≤0.6, and x:y:z ≠ 1:2:4；
SixMgyOz、SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,
0.4 < z/ (x+y+z) < 0.66, and x:y:z ≠ 1:2:4.
16. a kind of spin transistor, comprising:
First reference layer is formed by magnetic conductive material and has the fixed direction of magnetization；
First barrier layer is arranged on first reference layer and is formed by insulating materials；
Free layer is arranged on first barrier layer, is formed by magnetic conductive material and its direction of magnetization can be in response to
External magnetic field and freely change；
Second barrier layer is arranged on the free layer and is formed by insulating materials；
Second reference layer is arranged on second barrier layer, is formed by magnetic conductive material, and has fixed magnetization side
To the direction of magnetization of second reference layer and the direction of magnetization of first reference layer are parallel to each other；
Emitter is functionally connected to first reference layer；
Base stage is functionally connected to the free layer；And
Collector is functionally connected to second reference layer,
Wherein, first barrier layer and second barrier layer all have spinel-like crystal structure.
17. spin transistor as claimed in claim 16, wherein first barrier layer and second barrier layer are by being selected from
It is formed with the material of the following group: MgxAlyOzAnd ZnxAlyOz, wherein 0≤x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤0.4,0.3≤
Z/ (x+y+z)≤0.6, and x:y:z ≠ 1:2:4.
18. spin transistor as claimed in claim 16, wherein first barrier layer and second barrier layer are by being selected from
It is formed with the material of the following group: SixMgyOzAnd SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,0.4 < z/
, and x:y:z ≠ 1:2:4 (x+y+z) < 0.66.
19. spin transistor as claimed in claim 16, further includes:
Third barrier layer is arranged on second reference layer, is formed by insulating materials, and has spinel-like crystal knot
Structure.
20. spin transistor as claimed in claim 19, wherein the third barrier layer is by selected from the material shape of the following group
At:
MgxAlyOz、ZnxAlyOz, wherein 0≤x/ (x+y+z) < 0.5,0 < y/ (x+y+z)≤0.4,0.3≤z/ (x+y+z)≤
0.6, and x:y:z ≠ 1:2:4；
SixMgyOz、SixZnyOz, wherein 0 < x/ (x+y+z) < 0.33,0 < y/ (x+y+z) < 0.5,0.4 < z/ (x+y+z) < 0.66,
And x:y:z ≠ 1:2:4.
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| CN104009151A (en) * | 2014-05-27 | 2014-08-27 | 中国科学院物理研究所 | Closed magnetic tunnel junction |
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| CN103531707A (en) * | 2012-07-03 | 2014-01-22 | 中国科学院物理研究所 | Magnetic tunnel junction |
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