CN1113597A - Super-paramagnetic, ferromagnetic composite material with reversed parallel magnetization intensity - Google Patents
Super-paramagnetic, ferromagnetic composite material with reversed parallel magnetization intensity Download PDFInfo
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- CN1113597A CN1113597A CN 95111648 CN95111648A CN1113597A CN 1113597 A CN1113597 A CN 1113597A CN 95111648 CN95111648 CN 95111648 CN 95111648 A CN95111648 A CN 95111648A CN 1113597 A CN1113597 A CN 1113597A
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Abstract
The invention discloses a superparamagnet-ferromagnet composite material with anti-parallel array magnetization strength. The invention is characterized in that the composite material is compounded by a superparamagnet and a ferromagnet. The superparamagnet is formed by evenly distributing nano magnetic particles in a non-magnetic substance, the volume of each magnetic particle is as small as a magnetic domain, and the non-magnetic substance is filled among the particles, so that each particle can individually rotate along with the respond of the external magnetic field. The ferromagnet consists of separated geometrical shape anisotropic components, and can be one-dimensionally acicular, or two-dimensionally membranous.
Description
The present invention relates to a kind of magnetic composite-sodium rice magnetic material, is a kind of super paramagnetic-ferromagnetic composite material with arranged anti-parallel magnetization specifically.
In common magnetic material, the power of M-HLOOP is to being anticlockwise, and the area that circles and surrounded promptly equals the heat that this material is sent out.According to this principle, turn around clockwise, will cause obtaining heat from this material, just make it cooling.If can further improve the area that a clockwise circle is surrounded, and make it under AC magnetic field, to follow clockwise direction to be walked, a kind of novel cooling material has so just been arranged, and this cooling material can not produce pollution to environment.
The objective of the invention is in sodium rice material, seek and have composite material new or better magnetic and correlative amount performance thereof, a kind of super paramagnetic-ferromagnetic composite material with arranged anti-parallel magnetization promptly is provided, makes it on using, to have new purposes or on prior art, replace current material.
To achieve these goals, the present invention adopts following technical scheme: a kind of super paramagnetic-ferromagnetic composite material with arranged anti-parallel magnetization, it is characterized in that: it is by super paramagnet and ferromagnet is compound forms, should super paramagnet be to be evenly distributed in the namagnetic substance wherein by sodium rice magnetic-particle, particle volume must be enough little, make and in each particle, have only a magnetic domain, be full of namagnetic substance between particle, make each particle under specified temp (usually more than tens k), rotate thereupon and be mutually independently with the response of externally-applied magnetic field, wherein this ferromagnet is made up of the anisotropic constituent element of each discrete geometry, and it can be that one dimension is needle-like, two dimension is film like.
The present invention has the super paramagnetic-ferromagnetic composite material of the arranged anti-parallel magnetization, and wherein magnetic sodium rice particle and ferromagnet can be iron, cobalt, nickel element, also can be to have ferromagnetic alloy or compound, and they can be to form with a kind of ferromagnetic material.
Super paramagnetic-ferromagnetic composite material with arranged anti-parallel magnetization of the present invention, its a kind of version are that the little ferromagnetic spicule of lining up is in super paramagnetic medium.
Super paramagnetic one ferromagnetic composite material with arranged anti-parallel magnetization of the present invention, its a kind of version is, be evenly distributed on the sodium rice magnetic-particle in the namagnetic substance, near percolation the time, some particle interconnects and forms ferromagnetism, and the sodium rice particle that other still separate still has superparamagnetism, and promptly super paramagnet and ferromagnet exist together near percolation the time.
Super paramagnetic one ferromagnetic composite material with arranged anti-parallel magnetization of the present invention, its a kind of version is, be evenly distributed on the sodium rice magnetic-particle in the namagnetic substance, just during percolation, sodium rice magnetic metal particle has just and connects together, the separation of remaining is arranged, and the namagnetic substance of this moment also is nonmetal amorphous insulator simultaneously.
Super paramagnetic-ferromagnetic composite material with arranged anti-parallel magnetization of the present invention, its a kind of version is that super paramagnet-ferromagnet multilayer film is compound.
Good effect of the present invention is:
1, can to obtain negative remanent magnetization under certain condition be Mr/Ms＜0 to this composite material that obtains according to magnetostatic interaction and superposition principle, Mr: remanent magnetization, Ms: saturation magnetization, and Mr/Ms＜0 means at least that in magnetic field (H) is near zero the time, the M-HLOOP(magnetic hysteresis loop) direction is clockwise but not anticlockwise, this just is different from common magnetic material, and the direction of M-HLOOP is the counterclockwise rotation characteristics.Turn around clockwise, will cause obtaining heat, just make it cooling from this material.Utilize this character, material of the present invention can be made a kind of novel cooling material, and this cooling material can be to environment generation pollution, and relevant therewith can also make a kind of low-loss magnetic core.
2, can make the high density magnetic recording material.Close little ferromagnet with super paramagnet screen and can reduce even eliminate interaction between little ferromagnet (as single record cell), thus the noise of the tracer signal that reduces to produce therefrom.This principle can be used in existing parallel magnetic recording media, also can be used for perpendicular magnetic recording medium from now on, here the application on the perpendicular magnetic recording medium is discussed, according to Fig. 5 and primary Calculation, select diameter 20mm for use, the needle by pure iron of long 1 μ m will have enough anisotropy energies, make it not influenced by thermal excitation and turn to.Select for use simultaneously can be the sodium rice magnetic uniform particles made of suitable material be distributed in the insulator (percent by volume is 25%), if this super paramagnet screen closes the magnetic field of needle, then 1/4(a
2-π r
2)=π r
2, r: be the needle radius, a is needle spacing (as selecting square the arrangement for use), a
2=3 π r
2=3 π (100nm)
2=10
-11Cm
2, just surface density can reach 1/a
2=10
11Cm
-2, 2 " and the Disk(disk), also to have 2 * 10
12Bits that is to say, the principle of utilizing screen to close, and the density of perpendicular magnetic recording medium can reach so high theoretically, much larger than existing disk and according to the disk density in five to ten years of prior art expection.Experimentally the most difficult may be the thickness and the spacing of producing elongated needle and controlling them, and this technology is successfully realized in the dot matrix at Ni in University of Minnesota by stevenlhon etc., and in its technology, do not use super paramagnet to go screen to close, make its density also limited.The point of key of the present invention is to shield the interaction of closing between the magnetic recording unit with super paramagnet, thereby can the controlling recording noise when having improved packing density greatly.
3, near effective Hall coefficient of the huge Hall effect correspondence the percolation, can be comparable with general semi-conductive Hall effect, but better electric conductivity is arranged than semiconductor, can make bigger electric current by and do not generate heat, thereby improve the size of measuring voltage, so also just improved the signal to noise ratio of magnetic field sensor indirectly.The key here is a magnetic conductor, percolation and amorphous insulator.Magnetic conductor necessarily has the extraordinary Hall effect (increasing by 100 times) of the saturation magnetization of being proportional to; and percolation makes the sample effective thickness drop to particle diameter from itself thickness; the amorphous insulator makes its relevant amount of cross section scale that intersects with particle that further descends; therefore measure meeting less than particle diameter, thereby Hall effect is further increased.Present Ni-SiO at thickness 1 μ m
2Hall coefficient has reached 0.25Q/1KG in the system, further improves the possible further conductance of raising system of purity of Ni, thereby makes it to replace existing hall device.
Below in conjunction with drawings and Examples the present invention is elaborated.
Fig. 1 is three kinds of geometry schematic diagrames of the super paramagnet of uniform magnetization of the present invention, and wherein: (a) for lacking a needle-like space being arranged in infinitely great space, (b) be infinitely great space, (c) is the super paramagnetic spicule identical with (a) spicule;
The structural representation of the little ferromagnetic needle-like that Fig. 2 lines up for the present invention (length is much larger than its diameter) in uniform super paramagnetic medium;
(a) is that sodium rice magnetic-particle of the present invention is near percolation the time among Fig. 3, some connects together becomes discrete long ferromagnet (representing with the cinder line), and other side is still separation (representing with circle) and still have superparamagnetism, during (b) for sodium rice metallic magnetic grain percolation of the present invention, the connection of particle makes and has a conduction channel, by whole sample (representing), still have the particle (circle) of separation and discrete elongated ferromagnet (cinder line) this moment with thick black line;
Fig. 4 is the cross section structure schematic diagram of the super paramagnetic-ferromagnetic multilayer film of the present invention, and wherein open circles is the magnetic-particle of single domain, and thick black line is represented ferromagnetic thin film;
Fig. 5 is arranged in structural representation in the super paramagnetic medium for the present invention equably as the ferromagnetic spicule of the length of magnetic recording unit, open circles is the sodium rice magnetic-particle of single domain, thick black circle or thick black line are represented ferrometer, and wherein (a) is the sectional view of parallel needle-like, (b) is the vertical view of (a);
Fig. 6 is Nix-(Sio of the present invention
2)
1-xTransmission electron microscope details in a play not acted out on stage, but told through dialogues photo structural representation, the X by volume is calculated, its a is X=50%, b is X=60%;
Fig. 7 is a M-H curve of the present invention, and curve is a part of schematic diagram of 10KG → 10KG → 10KG, wherein (a) T=200K, X=55%, (b) T=5K, x=55%, (c) T=200K, X=60%;
Fig. 8 is a Mr-T curve of the present invention, and measuring process is for to add magnetic field to 10KG at 5K, allows magnetic field retreat to magnetization heating curve schematic diagram after zero then;
Fig. 9 is a Mr/Ms-X curve synoptic diagram of the present invention, and T=200K, Ms are the magnetization M when 10KG; The magnetization of Mr when reducing to zero from 10KG;
Figure 10 is the present invention (ρ xy/ ρ xys), (△ ρ xx/ ρ xx), (M/Ms) with change curve schematic diagram, the X=0.6 in magnetic field;
Figure 11 shows Log ρ xx, the Log| ρ hs| variation schematic diagram with X for the present invention.
Embodiment:
Nix-(SiO near Percolation
2)
1-xSystem, this system is obtained by shallow the penetrating of RF magnetic, during shallow penetrating, Ni and SiO
2Target basad ejaculation simultaneously, background pressure 10
-6Torr, the sample substrate temperature is 150 ℃, and must rotate simultaneously keeping uniformity, in the diffraction interpret sample that obtains with X-ray and transmission electron microscope mainly be face-centred cubic Ni uniform particles be distributed in the SiO of amorphous
2In.The photo that the bright field transmission electron microscope obtains illustrates the granular size of Ni about 3-8 μ m, and increases increase gradually with X.The details in a play not acted out on stage, but told through dialogues transmission electron microscope photo illustrates that the continuous property of particle also increases increase gradually with X as shown in Figure 6, and according to the magnetic interpretation of result, in the sample of X=30%, particle is incoherent with the response in magnetic field basically, and the sample of X=60% is ferromagnetic basically.Be not difficult to infer in X=40% and 50% the sample super paramagnet is arranged from Fig. 6, ferromagnet is also arranged.Fig. 6 (a) is corresponding to schematic diagram 3(a), Fig. 6 (b) is corresponding to Fig. 3 (b).
Negative remanent magnetization.Shown in Fig. 7 (a), to the sample of X=0.55 magnetization ionization meter, the variation of M with H be described, find when T=200K magnetic field drop to behind the 10KG zero after, M is from the occasion of becoming negative value.And this negative remanent magnetization has 9%(to compare with saturation magnetization Ms approximately).Same sample just has only positive remanent magnetization such as Fig. 7 (b) at 5K.The sample of X=0.6 also has only positive remanent magnetization (Mr/Ms＞0) at 200K, and when temperature rose, Mr lowered very soon, about 100K, Mr reindexing becomes negative value, about 200K, the value of Mr follows when 200K extra show to 10KG, drops to zero value again and meets substantially, as shown in Figure 8.Mr/Ms at 200K as shown in Figure 9 with the composition change curve, about 0.4 to 0.55, Mr/Ms bears to X, and in X＜0.3 o'clock, because super suitable effect Mr/Ms → 0, and X 〉=0.6, because ferromagnetic effects Mr/Ms＞0, negative Mr/Ms means super paramagnetic and ferromagnetic existence simultaneously.
Huge Hall effect.Figure 10 show ρ xy/ ρ xgs ,-M/MS and △ ρ xy/xx={ ρ xx(H)-ρ
(0)}/ρ
(0)With the change curve of H, T=5K, ρ xys and Ms are the Hall resistance rate and the magnetization after saturated, and the direction in magnetic field is added in the direction straight with costal fold.Figure 10 fully shows Pxy except an one-tenth being arranged than in H, also has an item that is directly proportional with M, Pxy is also saturated when M saturated (reaching Ms), we represent with Phs, and this increases along with reducing of X just, Figure 11 shows that Log ρ xx, Log| ρ hs| are with X(metal volume percentage) variation, tip is down represented the transition point Pc of metal-insulator, will be more useful for what be used for the sensitive instrument in magnetic field, X 〉=Pc.
Super paramagnetic-ferromagnetic composite material with arranged anti-parallel magnetization of the present invention can occur in following special construction at least:
1, as shown in Figure 2, structure of the present invention is that the little ferromagnetic spicule of lining up is in super paramagnetic medium.Its effective magnetic field E=-(4 π X-1) Ha.
2, as shown in Figure 3, structure of the present invention is that sodium rice magnetic-particle during near percolation is in namagnetic substance uniformly, in this case, the magnetic-particle that has interconnects owing to density increases, and another part remains separation, the particle that is in contact with one another is near percolation the time, its length can be much larger than its diameter, make its volume increase and present ferromagnetism, and because the magnetic anisotropy that shape causes, the magnetization of long grain is axial along it, supposes not have between long grain to interact, and all there is certain long grain in magnetic field when being added in any direction axially is parallel magnetic field, its effective magnetic field E=-(4 π X-1) Ha.
3, as shown in Figure 4, structure of the present invention is compound for super paramagnetic-ferromagnetic multilayer film, its effective magnetic field E=-(π X-1) Ha.
In above-mentioned three examples, Ha: externally-applied magnetic field, X=M/Ha.
Claims (6)
1, a kind of super paramagnetic--ferromagnetic composite material with arranged anti-parallel magnetization, it is characterized in that: it is by super paramagnet and ferromagnet is compound forms, should super paramagnet be to be evenly distributed in the namagnetic substance wherein by sodium rice magnetic-particle, the volume of each magnetic-particle is so small to have only a magnetic domain, be full of namagnetic substance between particle, make each particle rotate thereupon and be mutually independently with the response of externally-applied magnetic field, wherein this ferromagnet is made up of the anisotropic constituent element of each discrete geometry, and it can be that one dimension is needle-like, two dimension is film like.
2, the super paramagnetic-ferromagnetic composite material with arranged anti-parallel magnetization according to claim 1 is characterized in that: wherein this magnetic sodium rice particle and this ferromagnet are iron, cobalt, nickel element, or have ferromagnetic alloy or compound.
3, the super paramagnetic-ferromagnetic composite material with arranged anti-parallel magnetization according to claim 1 is characterized in that: its composition is that the little ferromagnetic spicule of lining up is in super paramagnetic medium.
4, the super paramagnetic-ferromagnetic composite material with arranged anti-parallel magnetization according to claim 1, it is characterized in that: its composition is the sodium rice magnetic-particle that is evenly distributed in the namagnetic substance, near percolation the time, there is sodium rice particle to interconnect and forms ferromagnetism, have the sodium rice particle that still separates still to have superparamagnetism.
5, super paramagnetic--the ferromagnetic composite material with arranged anti-parallel magnetization according to claim 1, it is characterized in that: its composition is the sodium rice magnetic-particle that is evenly distributed in the namagnetic substance, just during percolation, sodium rice magnetic metal particle has just and connects together, the separation of remaining is arranged, and the namagnetic substance of this moment also is nonmetal amorphous insulator simultaneously.
6, the super paramagnetic-ferromagnetic composite material with arranged anti-parallel magnetization according to claim 1, it is characterized in that: its composition is that super paramagnetic-ferromagnetic multilayer film is compound.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 95111648 CN1113597A (en) | 1995-06-02 | 1995-06-02 | Super-paramagnetic, ferromagnetic composite material with reversed parallel magnetization intensity |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 95111648 CN1113597A (en) | 1995-06-02 | 1995-06-02 | Super-paramagnetic, ferromagnetic composite material with reversed parallel magnetization intensity |
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| CN1113597A true CN1113597A (en) | 1995-12-20 |
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|---|---|---|---|
| CN 95111648 Pending CN1113597A (en) | 1995-06-02 | 1995-06-02 | Super-paramagnetic, ferromagnetic composite material with reversed parallel magnetization intensity |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105710384A (en) * | 2015-11-04 | 2016-06-29 | 中国科学院上海高等研究院 | One-dimensional nano bimetal alloy with hexagonal nail head structure and preparation method thereof |
-
1995
- 1995-06-02 CN CN 95111648 patent/CN1113597A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105710384A (en) * | 2015-11-04 | 2016-06-29 | 中国科学院上海高等研究院 | One-dimensional nano bimetal alloy with hexagonal nail head structure and preparation method thereof |
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