CN108598255A - A kind of more iron hetero-junctions and preparation method thereof - Google Patents
A kind of more iron hetero-junctions and preparation method thereof Download PDFInfo
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 182
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 81
- 238000002360 preparation method Methods 0.000 title claims description 15
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims abstract description 63
- 230000005291 magnetic effect Effects 0.000 claims abstract description 44
- 229910052712 strontium Inorganic materials 0.000 claims abstract description 26
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 claims abstract description 26
- 229910002113 barium titanate Inorganic materials 0.000 claims abstract description 24
- 239000000758 substrate Substances 0.000 claims abstract description 23
- 239000002253 acid Substances 0.000 claims abstract description 15
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000012545 processing Methods 0.000 claims abstract description 8
- 229940056319 ferrosoferric oxide Drugs 0.000 claims abstract description 5
- 238000000151 deposition Methods 0.000 claims description 38
- 230000008021 deposition Effects 0.000 claims description 31
- 229910052760 oxygen Inorganic materials 0.000 claims description 22
- 239000001301 oxygen Substances 0.000 claims description 22
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 21
- 238000004549 pulsed laser deposition Methods 0.000 claims description 17
- 238000005137 deposition process Methods 0.000 claims description 12
- 238000001816 cooling Methods 0.000 claims description 10
- 239000002061 nanopillar Substances 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 7
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical group [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 claims description 6
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 claims 1
- 229910052707 ruthenium Inorganic materials 0.000 claims 1
- 230000010287 polarization Effects 0.000 abstract description 12
- 230000005684 electric field Effects 0.000 abstract description 11
- 230000005415 magnetization Effects 0.000 abstract description 9
- 230000005621 ferroelectricity Effects 0.000 abstract description 7
- 230000005294 ferromagnetic effect Effects 0.000 abstract description 5
- 230000002441 reversible effect Effects 0.000 abstract description 5
- 150000002500 ions Chemical class 0.000 abstract description 4
- 238000003860 storage Methods 0.000 abstract description 4
- 230000015572 biosynthetic process Effects 0.000 abstract description 3
- 238000011161 development Methods 0.000 abstract description 2
- 238000002465 magnetic force microscopy Methods 0.000 description 7
- 239000000523 sample Substances 0.000 description 7
- 238000010587 phase diagram Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 230000005381 magnetic domain Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000012512 characterization method Methods 0.000 description 3
- 230000000087 stabilizing effect Effects 0.000 description 3
- 230000005290 antiferromagnetic effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000006870 function Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- NJPPVKZQTLUDBO-UHFFFAOYSA-N novaluron Chemical compound C1=C(Cl)C(OC(F)(F)C(OC(F)(F)F)F)=CC=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F NJPPVKZQTLUDBO-UHFFFAOYSA-N 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000004062 sedimentation Methods 0.000 description 2
- 229910002353 SrRuO3 Inorganic materials 0.000 description 1
- 229910002367 SrTiO Inorganic materials 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000004630 atomic force microscopy Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000005307 ferromagnetism Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- -1 oxygen ion Chemical class 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000000844 transformation Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N50/00—Galvanomagnetic devices
- H10N50/80—Constructional details
- H10N50/85—Magnetic active materials
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N50/00—Galvanomagnetic devices
- H10N50/01—Manufacture or treatment
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Abstract
The present invention provides a kind of more iron hetero-junctions, include strontium titanates substrate, ruthenic acid strontium bottom electrode layer, barium titanate ferroelectric layer and ferroferric oxide magnetic nano column array successively from bottom to up.For the present invention using barium titanate as ferroelectric layer, ferroso-ferric oxide is magnetic Nano column array, and more iron hetero-junctions of formation have excellent ferroelectricity, ferromagnetic property.Wherein, ferroso-ferric oxide not only can regulate and control magnetic property by ion motion, and electrode when can be as overturning iron electric polarization, it can realize stable, reversible at room temperature and non-volatile land productivity electric field controls magnetization orientation, the development for being conducive to future memory and spin electric device, the storage of ultrafast data and processing to realize high density and low-power consumption lay the foundation.
Description
Technical field
The present invention relates to multiferroic laminated film technical fields more particularly to a kind of more iron hetero-junctions and preparation method thereof.
Background technology
Now widely used magnetic random memory is maximum the disadvantage is that needing big electric current data are written, consumption is very high
Energy.And directly utilizing applied voltage that data are written, the mode of digital independent is then carried out with magnetic head to be greatly reduced
Be written energy consumption, and realize it is non-contact, non-destructively read, this storage mode be known as " readings of autotelegraph magnetic " store.To reality
Existing " reading of autotelegraph magnetic " storage, the part of most critical are to realize electric field overturning magnetic moment orientation function in the material.And in single-phase more iron
The automatically controlled magnetic effect realized in property material is limited to its antiferromagnetic order and cryogenic conditions, makes its application surface in practical devices
Face huge challenge.
In recent years, people have magneto-electric coupled theory and are more fully understood from, and there has also been more to sample preparation technology
It grasps consummately, therefore people more select magnetic electric compound material instead of monophase materials to probe into electric field overturning magnetization.Wherein,
Occur much about relevant by strain or the magneto-electric coupled realization electric field controls magnetism in interface in compound multiferroic hetero-junctions
Report, but these reports are typically the electric field controls intensity of magnetization rather than control magnetization orientation.
Invention content
The purpose of the present invention is to provide a kind of more iron hetero-junctions and preparation method thereof.More iron provided by the present invention are heterogeneous
Knot can realize that stables, reversible at room temperature and non-volatile land productivity electric field controls magnetize and take with excellent ferroelectricity, ferromagnetic property
To.
In order to achieve the above-mentioned object of the invention, the present invention provides following technical scheme：
The present invention provides a kind of more iron hetero-junctions, from bottom to up successively include strontium titanates substrate, ruthenic acid strontium bottom electrode layer,
Barium titanate ferroelectric layer and ferroferric oxide magnetic nano column array.
Preferably, the thickness of the ruthenic acid strontium bottom electrode layer is 10~40nm.
Preferably, the barium titanate ferroelectric layer is tetragonal phase, and thickness is 30~80nm.
Preferably, a diameter of 50~150 μm of single nano-pillar in the ferroferric oxide magnetic nano column array, height
For 10~30nm, the distance between adjacent nano column is 50~150 μm.
The present invention provides the preparation methods of more iron hetero-junctions described in above-mentioned technical proposal, include the following steps：
Using ruthenic acid strontium as target, the first deposition, shape are carried out in the upper surface of strontium titanates substrate using pulsed laser deposition
At ruthenic acid strontium bottom electrode layer；
Using barium titanate as target, second is carried out in the upper surface of the ruthenic acid strontium bottom electrode layer using pulsed laser deposition
Deposition forms barium titanate ferroelectric layer；
Mask plate is placed in the upper surface of the barium titanate ferroelectric layer, using ferroso-ferric oxide as target, using pulse laser
Sedimentation carries out third deposition on the surface for the barium titanate ferroelectric layer for being placed with mask plate, forms ferroferric oxide magnetic nano column
Array removes mask plate, obtains more iron hetero-junctions.
Preferably, strontium titanates substrate temperature is 650~750 DEG C in first deposition process, deposition oxygen pressure for 80~
120mTorr。
Preferably, depositing temperature is 700~800 DEG C in second deposition process；It is 2 × 10 to deposit oxygen pressure-3~8 ×
10-3Torr。
Preferably, depositing temperature is 300~500 DEG C in the third deposition process；It is 1 × 10 to deposit oxygen pressure-6~6 ×
10-6Torr。
Preferably, laser energy stands alone as 250~350mJ in first deposition, the second deposition and third deposition process,
Frequency stands alone as 5~15Hz.
Preferably, include that cooling is handled after second deposition, the cooling processing is 150~250Torr's in oxygen pressure
Under the conditions of carry out.
The present invention provides a kind of more iron hetero-junctions, from bottom to up successively include strontium titanates substrate, ruthenic acid strontium bottom electrode layer,
Barium titanate (BaTiO3) ferroelectric layer and ferroso-ferric oxide (Fe3O4) magnetic Nano column array.The present invention is with BaTiO3For ferroelectric layer,
Fe3O4More iron hetero-junctions for magnetic Nano column array, formation have excellent ferroelectricity, ferromagnetic property.Wherein, Fe3O4Not only may be used
With by ion motion regulate and control magnetic property, and can be used as overturn iron electric polarization when electrode, such Fe3O4Magnetic Nano
Pillar array structure saves the cumbersome process of plating top electrode layer compared to double-deck more iron hetero-junctions, to realize simply and accurately
BaTiO3Polarization overturning provides possibility.In the present invention, by applying different voltages, BaTiO can be caused3Polarization direction is overturn,
Make BaTiO3Positive polarisation charge migrate to two-phase interface, and these positive polarisation charges will repel in interface band just
The oxygen ion vacancy of electricity, leads to Fe3O4In oxygen ionic motion to surface, to cause Fe3O4Magnetic reciprocation in surface cell
From Fe (Td)-O-Fe(Oh) super reciprocation is changed into Fe (Td)-Fe(Oh) double cross interaction, the oxygen eight for the arranged anti-parallel that spins
For Spin-Parallel arrangement, magnetic reciprocation is changed into ferromagnetic coupling from antiferromagnetic coupling for face body and oxygen tetrahedron Fe ion transits
State, to realize stables at room temperature, reversible and non-volatile land productivity electric field controls magnetization orientation, be conducive to future memory with
The development of spin electric device, the storage of ultrafast data and processing to realize high density and low-power consumption lay the foundation.
In addition, the present invention provides the preparation methods of more iron hetero-junctions, using ruthenic acid strontium as target, using pulse laser
Sedimentation carries out the first deposition in the upper surface of strontium titanates substrate, forms ruthenic acid strontium bottom electrode layer；With BaTiO3For target, use
Pulsed laser deposition carries out the second deposition in the upper surface of the ruthenic acid strontium bottom electrode layer, forms BaTiO3Ferroelectric layer；Institute
State BaTiO3Mask plate is placed in the upper surface of ferroelectric layer, with Fe3O4For target, mask is being placed with using pulsed laser deposition
The BaTiO of plate3The surface of ferroelectric layer carries out third deposition, forms Fe3O4Magnetic Nano column array removes mask plate, obtains more iron
Hetero-junctions.The present invention prepares more iron hetero-junctions using pulsed laser deposition, and simple and practicable, process stabilizing, what is be prepared is more
There are not phase constituent diffusion phenomena in iron hetero-junctions, has very high repeatability.
Further, the present invention utilizes pulsed laser deposition, by accurately controlling oxygen pressure, with BaTiO3For ferroelectric layer,
Fe3O4For magnetic Nano column array, solves the tetragonal phase BaTiO that script growing environment has bigger difference3With Fe3O4It is difficult to coexist
The problem of, to prepare with Fe3O4More iron hetero-junctions of magnetic Nano column.
Description of the drawings
Fig. 1 is the structural schematic diagram of more iron hetero-junctions provided by the invention；
Fig. 2 is the X-ray diffractogram of more iron hetero-junctions prepared by embodiment 1；
Fig. 3 is the scanning electron microscope (SEM) photograph of more iron hetero-junctions prepared by embodiment 1；
Fig. 4 is Fe in more iron hetero-junctions prepared by Examples 1 to 33O4The atomic force microscopy diagram of magnetic Nano column；
Fig. 5 is the scanning transmission electron microscope figure of more iron hetero-junctions prepared by embodiment 1；
Fig. 6 is the ferroelectric hysteresis loop figure of more iron hetero-junctions prepared by embodiment 1；
Fig. 7 is the hysteresis loop figure of more iron hetero-junctions prepared by embodiment 1；
Fig. 8 is the magnetic force microscopy phase diagram of more iron hetero-junctions prepared by embodiment 1.
Specific implementation mode
The present invention provides a kind of more iron hetero-junctions, include strontium titanates (SrTiO successively from bottom to up3, referred to as STO) and lining
Bottom, ruthenic acid strontium (SrRuO3, referred to as SRO) bottom electrode layer, BaTiO3(referred to as BTO) ferroelectric layer and Fe3O4Magnetic Nano column battle array
Row.Fig. 1 be more iron hetero-junctions provided by the invention structural schematic diagram, as shown in Figure 1, sequentially consist of STO substrates,
SRO bottom electrode layers, BTO ferroelectric layers and Fe3O4Magnetic Nano column array.
In the present invention, the STO substrates high preferred orientation is preferably (100) direction, to ensure the more iron hetero-junctions obtained
With good phase structure.
In the present invention, the thickness of the SRO bottom electrode layers is preferably 10~40nm, and more preferably 15~35nm is optimal
It is selected as 20~30nm.In the present invention, if SRO bottom electrode layers are too thin, on the one hand electric conductivity can be caused bad, on the other hand,
It can lead to BTO ferroelectric layer semiconductor transformations after growth BTO ferroelectric layers, so that its insulating properties is substantially reduced, to influence its performance；If
SRO bottom electrode layers are too thick, its roughness can be made to increase, so that the BTO ferroelectric layers and Fe of subsequent growth3O4Magnetic Nano column
Array is difficult to realize epitaxial growth, and roughness also will increase, and leads to BTO ferroelectric layers and Fe3O4The hetero-junctions of magnetic Nano column array
Interface is destroyed.
In the present invention, the BTO ferroelectric layers are preferably tetragonal phase.In the present invention, the BTO of tetragonal phase only exists 180 °
With 90 ° of domain structures, therefore controllability is stronger.In the present invention, the thickness of the BTO ferroelectric layers is preferably 30~80nm, more excellent
It is selected as 40~70nm, most preferably 50~60nm.In the present invention, thickness can make BTO ferroelectric layers within the scope of 30~80nm
With preferable polarization rollover characteristics：When thickness is less than 30nm, BTO ferroelectric layers easily puncture, and fatigue properties are poor, are unfavorable for realizing
The regulation and control repeatedly of automatically controlled magnetic domain；When thickness is more than 80nm, BTO ferroelectric layers need to realize overturning under the effect of big voltage, unfavorable
In practical application.
In the present invention, the Fe3O4The diameter of single nano-pillar is preferably 50~150 μm in magnetic Nano column array, more
Preferably 70~130 μm, most preferably 90~110 μm；Highly preferred is 10~30nm, more preferably 15~25nm, most preferably
For 20nm；The distance between adjacent nano column is preferably 50~150 μm, more preferably 70~130 μm, most preferably 90~110 μ
m.The present invention is with Fe3O4For magnetic Nano column array, Fe3O4It not only can regulate and control magnetic property by ion motion, and can make
For overturning iron electric polarization when electrode, to realize stable at room temperature, reversible and non-volatile land productivity electric field controls magnetization orientation；
Fe3O4For magnetic Nano pillar array structure, more iron hetero-junctions of formation reduce the beam of substrate compared to double-deck more iron hetero-junctions
Effect is tied up, so as to realize that stronger electric field overturns magnetic domain performance.
The present invention provides the preparation methods of more iron hetero-junctions described in above-mentioned technical proposal, include the following steps：
Using STO as target, the first deposition is carried out in the upper surface of STO substrates using pulsed laser deposition, forms the bottoms SRO
Electrode layer；
Using BTO as target, the second deposition is carried out in the upper surface of the SRO bottom electrode layers using pulsed laser deposition,
Form BTO ferroelectric layers；
Mask plate is placed in the upper surface of the BTO ferroelectric layers, with Fe3O4For target, put using pulsed laser deposition
The surface for being equipped with the BTO ferroelectric layers of mask plate carries out third deposition, forms Fe3O4Magnetic Nano column array removes mask plate, obtains
Much iron hetero-junctions.
The present invention carries out the first deposition, shape using SRO as target, using pulsed laser deposition in the upper surface of STO substrates
At SRO bottom electrode layers.The present invention does not have the source of the SRO special restriction, use well known to those skilled in the art
SRO targets.
In the present invention, STO substrate temperatures are preferably 650~750 DEG C in first deposition process, more preferably
700℃；It is preferably 80~120mTorr, more preferably 90~110mTorr, most preferably 100mTorr to deposit oxygen pressure；Laser energy
Amount is preferably 250~350mJ, more preferably 300mJ；Frequency is preferably 5~15Hz, more preferably 10Hz.The present invention is for institute
The time for stating the first deposition does not have special restriction, and it is 10~40nm that can make the thickness for the SRO bottom electrode layers to be formed.
In the present invention, when being deposited using pulsed laser deposition, STO substrates are preferably placed on pulse laser
On pedestal in the growth chamber device of depositing system, SRO targets are placed on the target position of impulse laser deposition system, by target position tune
It is whole in the surface of STO substrates, STO substrates at a distance from SRO targets be 60cm.
After the upper surface of STO substrates forms SRO bottom electrode layers, the present invention is using BTO as target, using pulsed laser deposition
Method carries out the second deposition in the upper surface of the SRO bottom electrode layers, forms BTO ferroelectric layers.Source of the present invention for the BTO
There is no special restriction, using BTO targets well known to those skilled in the art.
In the present invention, depositing temperature is preferably 700~800 DEG C in second deposition process, more preferably 750 DEG C；
Deposit oxygen pressure preferably 2 × 10-3~8 × 10-3Torr, more preferably 4 × 10-3~6 × 10-3Torr；Laser energy is preferably
250~350mJ, more preferably 300mJ；Frequency is preferably 5~15Hz, more preferably 10Hz.In the present invention, described second is heavy
Laser energy and frequency are preferably consistent with first deposition during product.The present invention does not have the time of second deposition
Special restriction, it is 30~80nm that can make the thickness for the BTO ferroelectric layers to be formed.
After completing the second deposition, the present invention is preferably different by the more iron with BTO ferroelectric layers obtained after second deposition
Matter knot presoma carries out cooling processing；The cooling processing preferably carries out under conditions of oxygen pressure is 150~250Torr, more excellent
It is selected as 200Torr.In the present invention, the cooling processing can prevent BTO ferroelectric layers from inversion of phases occurs.The present invention preferably passes through
Cooling processing makes the temperature of more iron hetero-junctions presomas be reduced to 350~450 DEG C, more preferably 400 DEG C.The present invention is for described
Cooling handles not special restriction, using cooling method well known to those skilled in the art and rate of temperature fall.
After the upper surface of SRO bottom electrode layers forms BTO ferroelectric layers, the present invention is put in the upper surface of the BTO ferroelectric layers
Mask plate is set, with Fe3O4For target, the is carried out on the surface for the BTO ferroelectric layers for being placed with mask plate using pulsed laser deposition
Three depositions, form Fe3O4Magnetic Nano column array removes mask plate, obtains more iron hetero-junctions.In the present invention, the mask plate
It is preferred that with proper alignment circular hole, and the diameter of the circular hole preferably with Fe3O4It is single in magnetic Nano column array
The diameter of nano-pillar is consistent, the distance of adjacent circular hole preferably with Fe3O4The distance of adjacent nano column in magnetic Nano column array
Unanimously.The present invention is for the Fe3O4There is no special restriction, using Fe well known to those skilled in the art3O4Target.
In the present invention, depositing temperature is preferably 300~500 DEG C in the third deposition process, more preferably 350~
450 DEG C, most preferably 400 DEG C；Deposit oxygen pressure preferably 1 × 10-6~6 × 10-6Torr, more preferably 2 × 10-6~5 × 10- 6Torr, most preferably 3 × 10-6~4 × 10-6Torr；Laser energy is preferably 250~350mJ, more preferably 300mJ；Frequency
Preferably 5~15Hz, more preferably 10Hz.In the present invention, in the third deposition process laser energy and frequency preferably with
First deposition is consistent.The time that the present invention deposits the third does not have special restriction, can make the Fe to be formed3O4
The height of single nano-pillar is 10~30nm in magnetic Nano column array.
Below in conjunction with the embodiment in the present invention, the technical solution in the present invention is clearly and completely described.It is aobvious
So, described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.Based on the reality in the present invention
Example is applied, every other embodiment obtained by those of ordinary skill in the art without making creative efforts all belongs to
In the scope of protection of the invention.
Embodiment 1
(1) STO substrates are placed on the pedestal in the growth chamber device of impulse laser deposition system, SRO targets is placed
On the target position of impulse laser deposition system, target position is adjusted in the surface of STO substrates, STO substrates are at a distance from SRO targets
For 60cm；STO underlayer temperatures are heated to 700 DEG C by closing chamber device, laser energy be 300mJ, frequency 10Hz, partial pressure of oxygen
Under conditions of 100mTorr, SRO bottom electrode layers are grown in the upper surface of STO substrates using pulsed laser deposition, until described
The thickness of SRO bottom electrode layers is 30nm；
(2) 750 DEG C, laser energy 300mJ, frequency 10Hz, partial pressure of oxygen be 5 × 10-3Under conditions of Torr, utilize
BTO targets grow tetragonal phase BTO ferroelectric layers in the upper surface for the SRO bottom electrode layers that the step (1) obtains, until the BTO iron
The thickness of electric layer is 50nm, is then cooled to 400 DEG C under conditions of oxygen pressure is 200Torr；
(3) by with proper alignment circular hole and hole diameter be 100 μm mask plate be placed on the step (2)
The upper surface of the BTO ferroelectric layers arrived, 400 DEG C, laser energy 300mJ, frequency 10Hz, partial pressure of oxygen be 4 × 10-6Torr's
Under the conditions of, utilize Fe3O4Target grows Fe on the surface for the BTO ferroelectric layers for being placed with mask plate3O4Magnetic Nano column array, until
A diameter of 100 μm of single nano-pillar, be highly 20nm, remove mask plate, obtain more iron hetero-junctions.
Embodiment 2
Prepare more iron hetero-junctions according to the method for embodiment 1, the difference is that be in step (2) be cooled to 350 DEG C, and
It is to grow Fe under the conditions of 350 DEG C in step (3)3O4Magnetic Nano column array.
Embodiment 3
Prepare more iron hetero-junctions according to the method for embodiment 1, the difference is that be in step (2) be cooled to 450 DEG C, and
It is to grow Fe under the conditions of 450 DEG C in step (3)3O4Magnetic Nano column array.
Embodiment 4
The more iron hetero-junctions prepared to Examples 1 to 3 characterize, specific as follows：
Fig. 2 is X-ray diffraction (XRD) figure of more iron hetero-junctions prepared by embodiment 1.As shown in Figure 2, SRO bottom electrode layers,
BTO ferroelectric layers and Fe3O4Magnetic Nano column array be preferred orientation growth, the preferred orientation direction of growth be respectively (200),
(002) and (400), illustrate that preparation method provided by the invention is suitble to grow the hetero-junctions of extension.
Fig. 3 is scanning electron microscope (SEM) figure of more iron hetero-junctions prepared by embodiment 1.From the figure 3, it may be seen that more iron are heterogeneous
There is the Fe of proper alignment on the surface of knot3O4Nano column array, columnar Fe3O4Regular circular, each Fe is presented3O4Nano-pillar
Diameter is close to 100 μm, and each Fe3O4The sign that the periphery of nano-pillar is not spread, these shape characteristics and Fig. 1
Shown in more iron hetero-junctions structural schematic diagram it is consistent.
Fig. 4 is Fe in more iron hetero-junctions prepared by Examples 1 to 33O4Atomic force microscope (AFM) figure of magnetic Nano column,
Wherein, Fig. 4 (a), 4 (b) and 4 (c) are respectively Fe in more iron hetero-junctions prepared by embodiment 1, embodiment 2 and embodiment 33O4Magnetic
Property nano-pillar AFM figure.As shown in figure 4, can be seen that three by observation chart 4 (a), 4 (b) and the contrast item on the right side of 4 (c)
The roughness of sample illustrates Fe within 400pm3O4Magnetic Nano column epitaxial growth is preferable, also reflects BTO iron from side
Electric layer and SRO bottom electrode layers all have good epitaxial structure.
Fig. 5 is scanning transmission electron microscope (STEM) figure of more iron hetero-junctions prepared by embodiment 1.Wherein, Fig. 5 (a) is more iron
The low range STEM of hetero-junctions schemes, as can be seen from the figure SRO bottom electrode layers, BTO ferroelectric layers and Fe3O4Magnetic Nano column array
Inside possesses consistent contrast, and the interface between different phases is apparent from, and illustrates that more iron hetero-junctions have good crystal matter
Amount.Fig. 5 (b) and Fig. 5 (c) is respectively SRO/BTO two-phase interfaces and BTO/Fe3O4High-resolution STEM figures at two-phase interface,
In, it can be found that inside SRO bottom electrode layers there is very regular lattice to arrange in Fig. 5 (b), illustrate its excellent crystal matter
Amount, this allows it to bear the function of buffer layer and hearth electrode well in hetero-junctions.In addition, SRO bottom electrode layers and BTO
Ferroelectric layer has clear and legible interface, and has with SRO lattices in the dozens of BTO lattices near SRO bottom electrode layers
Have a good epitaxial relationship, Atomic Arrangement rule in BTO lattices, in Fig. 5 (c) near BTO ferroelectric layers regional area Fe3O4
Lattice is not very clear, this may be due to Fe3O4Lattice constant and the lattice constant of BTO be not stringent multiple proportion
Caused.In addition to this, Fe3O4Internal lattice shows and the good epitaxial relationship of BTO ferroelectric layers on the whole.
Ferroelectric properties characterization is carried out to more iron hetero-junctions prepared by embodiment 1, it is specific as follows：At room temperature, ferroelectricity point is utilized
Probe is respectively placed in Fe by analyzer by the way of " one bottom of a top "3O4On SRO hearth electrodes, by applying different voltages, obtain
Much ferroelectric hysteresis loops of iron hetero-junctions.
Fig. 6 is ferroelectric hysteresis loop (P-E) figure of more iron hetero-junctions prepared by embodiment 1.It will be appreciated from fig. 6 that more iron hetero-junctions
Although ferroelectricity tests the influence for receiving leakage current, ferroelectric hysteresis loop totally remains to show typical ferroelectric hysteresis loop feature.Electricity
Saturated polarization, residual polarization and the coercive field of hysteresis curves increase with the increase of applied voltage, and ferroelectric hysteresis loop is in applied voltage
To reach saturation when 7V.Saturation ferroelectric hysteresis loop possesses saturated polarization at maximum voltage 7V, when polarization value is dropped from 7V applied voltages
For 0V when, more iron hetero-junctions possess about 15 μ C/cm2Residual polarization.BTO iron in these result verifications more iron hetero-junctions
The good ferroelectricity of electric layer.
Magnetic performance characterization is carried out to more iron hetero-junctions prepared by embodiment 1, it is specific as follows：At room temperature, vibration sample is utilized
Product magnetometer on the vibration rod by the installation of more iron hetero-junctions is placed at the induction coil line of centres of magnetic pole center, then by applying
Add knead dough external magnetic field in the face of ± 15000Oe, more iron hetero-junctions that can be magnetized uniformly；Pass through the pass in magnetic field and total magnetic moment
System, obtains the hysteresis loop of more iron hetero-junctions.
Fig. 7 is hysteresis loop (M-H) figure of more iron hetero-junctions prepared by embodiment 1, and wherein IP and OP are respectively represented in face
The data that knead dough outer magnetic field direction is tested.As shown in Figure 7, the M-H loop lines that more iron hetero-junctions are measured in IP and OP are all outside
Add and typical ferromagnetism hysteresis loop feature is presented under the magnetic fields ± 15000Oe, wherein more iron hetero-junctions magnetic under the magnetic fields IP and OP
The saturation magnetisation value of hysteresis curves is respectively 488.4emu/cc and 387.3emu/cc, corresponding magnetic coercive field all in 380Oe or so,
With Fe3O4Soft magnetic property match.These results prove the Fe prepared on BTO ferroelectric layers using mask plate technique3O4Nanometer
Column array has excellent agnetic property at room temperature m.
Electric field controls magnetization orientation performance characterization is carried out to more iron hetero-junctions prepared by embodiment 1, it is specific as follows：Room temperature
Under, using atomic force microscope, more iron hetero-junctions are fixed on sample stage, and probe tip is displaced downwardly to Fe3O4Upper surface,
It is polarized to more iron hetero-junctions application different voltages using the domain mode of writing in piezoelectricity force microscope, then utilizes magnetic force
Its magnetization orientation variation of micro- sem observation, obtains the magnetic force microscopy phase diagram of more iron hetero-junctions.
Fig. 8 is magnetic force microscopy (MFM) phase diagram of more iron hetero-junctions prepared by embodiment 1.As shown in Figure 8, by by
The negative voltage of cumulative big write-in, Fe3O4MFM phase diagrams gradually change, this is because with write-in voltage increase, BTO
Polarization orientation be affected, when voltage reaches 6V, its polarization direction is totally turned over, and Fe at this time3O4Magnetic domain by BTO normalizings
The polarization orientation of change is influenced, to regulate and control Fe3O4Lacking oxygen distribution, therefore Fe3O4Magnetic domain also become same and take
To；And after positive voltage is written, Fe3O4MFM phase diagrams all and Fe3O4Original state MFM phase diagrams it is identical.These results
Prove that write-in negative voltage can normalize Fe3O4Magnetic domain be orientated, and positive voltage, which is written, can restore Fe3O4Initial magnetic domain take
To, and these are to Fe3O4The control of magnetic domain is all non-volatile.
As seen from the above embodiment, more iron hetero-junctions provided by the present invention have excellent ferroelectricity, ferromagnetic property, can
Realize stable at room temperature, reversible and non-volatile land productivity electric field controls magnetization orientation.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications are also answered
It is considered as protection scope of the present invention.
Claims (10)
1. a kind of more iron hetero-junctions, include successively from bottom to up strontium titanates substrate, ruthenic acid strontium bottom electrode layer, barium titanate ferroelectric layer and
Ferroferric oxide magnetic nano column array.
2. more iron hetero-junctions according to claim 1, which is characterized in that the thickness of the ruthenic acid strontium bottom electrode layer be 10~
40nm。
3. more iron hetero-junctions according to claim 1, which is characterized in that the barium titanate ferroelectric layer is tetragonal phase, thickness
For 30~80nm.
4. more iron hetero-junctions according to claim 1, which is characterized in that in the ferroferric oxide magnetic nano column array
A diameter of 50~150 μm of single nano-pillar, are highly 10~30nm, and the distance between adjacent nano column is 50~150 μm.
5. the preparation method of any one of Claims 1 to 4 more iron hetero-junctions, includes the following steps：
Using ruthenic acid strontium as target, the first deposition is carried out in the upper surface of strontium titanates substrate using pulsed laser deposition, forms ruthenium
Sour strontium bottom electrode layer；
Using barium titanate as target, second is carried out in the upper surface of the ruthenic acid strontium bottom electrode layer using pulsed laser deposition and sunk
Product forms barium titanate ferroelectric layer；
Mask plate is placed in the upper surface of the barium titanate ferroelectric layer, using ferroso-ferric oxide as target, using pulsed laser deposition
Method carries out third deposition on the surface for the barium titanate ferroelectric layer for being placed with mask plate, forms ferroferric oxide magnetic nano column battle array
Row remove mask plate, obtain more iron hetero-junctions.
6. preparation method according to claim 5, which is characterized in that the temperature of strontium titanates substrate in first deposition process
Degree is 650~750 DEG C, and deposition oxygen pressure is 80~120mTorr.
7. preparation method according to claim 5, which is characterized in that depositing temperature is 700 in second deposition process
~800 DEG C；It is 2 × 10 to deposit oxygen pressure-3~8 × 10-3Torr。
8. preparation method according to claim 5, which is characterized in that depositing temperature is 300 in the third deposition process
~500 DEG C；It is 1 × 10 to deposit oxygen pressure-6~6 × 10-6Torr。
9. according to claim 5~8 any one of them preparation method, which is characterized in that it is described first deposition, second deposition and
Laser energy stands alone as 250~350mJ in third deposition process, and frequency stands alone as 5~15Hz.
10. the preparation method according to claim 5 or 7, which is characterized in that include that cooling is handled after second deposition,
The cooling processing carries out under conditions of oxygen pressure is 150~250Torr.
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