The method of ordering center of area tetragonal iron platinum particle size in the doped thinning film
Technical field
The present invention relates to the method for ordering center of area tetragonal iron platinum particle size in a kind of doped thinning film, more specifically, is a kind of by nitrating in film and anneal refinement L1
0The preparation method of structural iron platinum grain is to satisfy it in the requirement of using aspect the super-high density magnetic recording material.
Background technology
Particle film is a candidate material of realizing the super-high density magnetic information storage, and recording density is expected to reach 10-100Gb/in
2Under so high area recording density, the key issue that exists is how to improve the coercive force of material, reduce particle size, weaken the particle interphase interaction and improve thermostability at present.C is the ideal fertile material.Because (1) mutual solubility of C and Fe, Co and Ni is very little, the two is compound can be easy to form the particle film structure; (2) compare with nonmagnetic material, C can isolate (magnetic isolation) ferromagnetic particle better, effectively reduces the spin-exchange-coupled between the particle, reduces media noise, improves coercive force; (3) acidproof, the resistance to oxidation, anticorrosive of C can be protected magnetic recording unit well; (4) because C itself is exactly good solid lubricant, not only can further reduce the flying height of magnetic head, improve flight velocity, compare as the high density recording material of lubricant film with C, also reduce the macro-scale of recording materials with other.
Recently, no matter aspect fundamental research or aspect applied research, because high magnetocrystalline anisotropy can improve the coercive force of sample, so have high magnetocrystalline anisotropy constant (~ 7 * 10
7Erg/cm
3) the FePt alloy of center of area four directions (fct) structure become people's research focus.Usually, the FePt film for preparing with sputtering method has unordered face-centered cubic (fcc) structure, obtain the fct phase, need carry out high-temperature heat treatment to film.For pure FePt continuous film, thermal treatment temp is generally more than 500 ℃.So high temperature can make the FePt particle aggregation become big particle, thereby reduces recording density, the requirement that does not reach the super-high density magnetic recording material.Therefore, how to reduce FePt particulate size in the sample and become the hot issue that people pay close attention to.
Summary of the invention
In high-density magnetic recording media, the raising of area density need reduce the reduction of particle size in the dielectric material.If the FePt with high magnetocrystalline anisotropy is applied in the super-high density magnetic recording material, must guarantee that under high annealing temperature particle size is enough little.The reduction of the present invention by mixing the nitrogen success FePt particulate size in the FePt-C membrana granulosa, for its application on the super-high density magnetic recording media provides possibility.
The present invention is when preparation FePt-C particle film, and the base material that is adopted is single crystalline Si (a 100) substrate.
Concrete preparation method of the present invention realizes through following steps:
1) the DPS-II type ultrahigh vacuum(HHV) subtend target magnetic control sputtering coating equipment that adopts scientific instrument development center, Chinese Academy of Sciences Shenyang to produce, a pair of purity of installation is 99.99% graphite target on the target head of subtend, a N utmost point as magnetic line of force, the other end is the S utmost point; The thickness of target is 5mm, and diameter is 100mm; Each 8 of pure Fe (99.99%) and Pt (99.99%) are evenly placed on surface at the C target, and the area of each tinsel is 0.8cm
2, make that the atomic ratio of Fe and Pt is 52: 48 in the sample; The C atomic percent is 47% in the film.Distance between two targets is 100mm, and the axis of target and the distance between the specimen holder are 100mm;
2), be installed on the midperpendicular of subtend target line with behind the substrate material surface contaminant removal;
3) unlatching DPS-II subtend target magnetic control sputtering equipment successively starts the one-level mechanical pump and the secondary molecular pump vacuumizes, and vacuum tightness is 2 * 10 at the bottom of the back of the body of sputtering chamber
-4Pa;
4) feeding purity to vacuum chamber is 99.999% Ar (32sccm) and N
2Mixed gas (8sccm) remains on 0.5Pa with vacuum tightness;
5) open shielding power supply, apply the electric current of 0.2A and the volts DS about 1000V on a pair of C target, pre-sputter 10 minutes waits sputtering current and voltage stable;
6) plate washer of opening on the substrate frame begins sputter, and substrate position is fixed; In the sputter procedure, substrate is not heated;
7) after sputter finishes, close the plate washer on the substrate frame, close shielding power supply then, stop to feed sputter gas Ar and N
2, open slide valve fully, continue to vacuumize, close vacuum system then; After treating system cools, charging into purity to vacuum chamber is 99.999% nitrogen, opens vacuum chamber, takes out sample.
8) sample is put into annealing furnace and anneal, successively start the vacuum chamber that one-level mechanical pump and secondary molecular pump are taken out annealing furnace, vacuum tightness is 8 * 10 at the bottom of the back of the body of annealing furnace vacuum chamber
Pa; With the heat-up rate of 10 ℃ of per minutes, be warming up to 650 ℃, under 650 ℃ of temperature, kept 1 hour, after this rate of temperature fall of 5 ℃ of per minutes is lowered the temperature, reduces to room temperature and takes out sample
FePt-C particle film with center of area tetragonal involved in the present invention has potential in the super-high density magnetic recording media uses, and the present invention adopt the facing targets sputtering method be conventional means, the target of industrial production thin-film material select simple and the target rate of utilization than advantages such as height.
For confirming embodiment of the present invention, we have carried out X-ray diffraction to prepared film of the present invention, the measurement of transmission electron microscope and x-ray photoelectron power spectrum.
The FePt-C particle film of the ordering center of area tetragonal that the prepared nitrogen of the present invention mixes can be by growth of FePt particulate and polymerization in the effective control annealing process of mixing of nitrogen, for it provides possibility in the application aspect the super-high density magnetic recording media; Effect is as follows:
1, in the FePt-C particle film of the ordering center of area tetragonal that mixes of the prepared nitrogen of the present invention FePt particulate size than there not being the FePt particle size in the nitrating sample obviously to reduce.
2, nitrogen overflows from film in annealing process, makes and does not mix other element in the sample, and unlike mixing other metallic element, a large amount of metal that mixes in annealing back still is retained in the film sample.In addition, nitrogen is also both economical, and is pollution-free.
Description of drawings
Fig. 1: the X-ray diffraction spectrum of 1 hour FePt-C particle films of prepare among the present invention 650 ℃ annealing, (a) do not mix the sample (the nitrogen flow is 0) of nitrogen, (b) mix the sample (the nitrogen flow is 8sccm) of nitrogen.
Fig. 2: the transmission electron microscope image of 1 hour FePt-C particle films of prepare among the present invention 650 ℃ annealing, (a) do not mix the sample (the nitrogen flow is 0) of nitrogen, (b) mix the sample (the nitrogen flow is 8sccm) of nitrogen.
Fig. 3: the nitrogen of the present invention preparation mixes the X-ray tube electronic spectrum of 1 hour the FePt-C particle films of 650 ℃ of annealing of the preparation attitude of (the nitrogen flow is 8sccm) and preparation, (a) C
1s, (b) N
1s, (c) Pt
4f(d) Fe
2p
Embodiment
According to structure and property analysis that we carry out sample prepared among the present invention, the preferred forms that below the reactive sputtering method preparation is had the iron nitride thin film of big unusual Hall effect is described in detail:
Embodiment 1:
1) the DPS-II type ultrahigh vacuum(HHV) subtend target magnetic control sputtering coating equipment that adopts scientific instrument development center, Chinese Academy of Sciences Shenyang to produce, a pair of purity of installation is 99.99% graphite target on the target head of subtend, a N utmost point as magnetic line of force, the other end is the S utmost point; The thickness of target is 5mm, and diameter is 100mm; Each 8 of pure Fe (99.99%) and Pt (99.99%) are evenly placed on surface at the C target, and the area of each tinsel is 0.8cm
2, make that the atomic ratio of Fe and Pt is 52: 48 in the sample; The C atomic percent is 47% in the film.Distance between two targets is 100mm, and the axis of target and the distance between the specimen holder are 100mm;
2), be installed on the midperpendicular of subtend target line with behind the substrate material surface contaminant removal;
3) unlatching DPS-II subtend target magnetic control sputtering equipment successively starts the one-level mechanical pump and the secondary molecular pump vacuumizes, and vacuum tightness is 2 * 10 at the bottom of the back of the body of sputtering chamber
-4Pa;
4) feeding purity to vacuum chamber is 99.999% Ar (32sccm) and N
2Mixed gas (8sccm) remains on 0.5Pa with vacuum tightness;
5) open shielding power supply, apply the electric current of 0.2A and the volts DS about 1000V on a pair of C target, pre-sputter 10 minutes waits sputtering current and voltage stable;
6) plate washer of opening on the substrate frame begins sputter, and substrate position is fixed; In the sputter procedure, substrate is not heated;
7) after sputter finishes, close the plate washer on the substrate frame, close shielding power supply then, stop to feed sputter gas Ar and N
2, open slide valve fully, continue to vacuumize, close vacuum system then; After treating system cools, charging into purity to vacuum chamber is 99.999% nitrogen, opens vacuum chamber, takes out sample.
8) sample is put into annealing furnace and anneal, successively start the vacuum chamber that one-level mechanical pump and secondary molecular pump are taken out annealing furnace, vacuum tightness is 8 * 10 at the bottom of the back of the body of annealing furnace vacuum chamber
-4Pa; With the heat-up rate of 10 ℃ of per minutes, be warming up to 650 ℃, under 650 ℃ of temperature, kept 1 hour, after this rate of temperature fall of 5 ℃ of per minutes is lowered the temperature, reduces to room temperature and takes out sample.
Embodiment 2:
Step is identical with embodiment one, and different is: in the step 4 to feed purity to vacuum chamber be 99.999% Ar (32sccm) gas, vacuum tightness is remained on 0.5Pa.
Fig. 1 has provided the X-ray diffraction spectrum of 1 hour the FePt-C particle film of 650 ℃ of annealing for preparing among the present invention, (a) does not mix the sample (the nitrogen flow is 0) of nitrogen, (b) mixes the sample (the nitrogen flow is 8sccm) of nitrogen.As can be seen from the figure, do not mix all contain ordering in nitrogen and the annealing specimen that mixes nitrogen center of area four directions FePt mutually, body-centred cubic Fe has not appearred but mix in the sample of nitrogen, illustrate that mixing of nitrogen promoted the formation of ordering center of area tetragonal FePt.
Fig. 2 has provided the transmission electron microscope image of 1 hour the FePt-C particle film of 650 ℃ of annealing for preparing among the present invention, (a) does not mix the sample (the nitrogen flow is 0) of nitrogen, (b) mixes the sample (the nitrogen flow is 8sccm) of nitrogen.As can be seen from the figure, the particle that does not mix in the sample of nitrogen is bigger, the particulate polymerism occurs; And the particle size in the sample of nitrating is very little, and disperses finely, illustrates that being inserted with of nitrogen is beneficial to the refinement of ordering center of area tetragonal FePt particle size in the sample.
The nitrogen that Fig. 3 has provided the present invention's preparation mixes the X-ray tube electronic spectrum of 1 hour the FePt-C particle films of 650 ℃ of annealing of the preparation attitude of (the nitrogen flow is 8sccm) and preparation, (a) C
1s, (b) N
1s, (c) Pt
4f(d) Fe
2pAs can be seen from the figure, C in the preparation aspect product
1sBound energy be 285.5eV, from the sp among the non-crystalline state C
3-C, and after annealed, C
1sBound energy be 284.6 eV, from sp
2-C illustrates amorphous C parent greying behind the high temperature annealing.N in the preparation aspect product
1sBound energy be 399.4eV and 397.3eV, correspond respectively to N-sp
3C and FeN compound.Pt
4fBound energy be always 72.0eV, from the metallic state Pt of simple substance.Fe in the preparation aspect product
2pBound energy be 710.7eV, corresponding Fe
2+, and at 2p
1/2And 2p
3/2Satellites has appearred in the centre, illustrates to have Fe
3+, from the FeN compound; After annealed, Fe
2pBound energy be 707.6, corresponding simple substance Fe.These results can interpret sample in the variation of chemical state in preparation and anneal process of each element, also further illustrate the forming process of sample.The FePt film for preparing at a lower temperature with sputtering method is a non-crystalline state, and this moment is owing to Fe in sputter procedure
2+Or Fe
3+Ion and N ionic electronegativity differ greatly, and are combined together to form the FeN compound easily, so there is the nitride of Fe to form in the sample.When annealing temperature when higher, the FeN compound decomposition, the N atom breaks away from from film, at this moment Fe atom and Pt atom are in conjunction with forming L1
0The FePt alloy of structure mainly is L1 in the sample
0The FePt phase of structure.
The method of ordering center of area tetragonal iron platinum particle size in the doped thinning film that the present invention proposes, be described by embodiment, person skilled obviously can be changed or suitably change and combination content as herein described in not breaking away from content of the present invention, spirit and scope, realizes the present invention.Special needs to be pointed out is, the replacement that all are similar and change apparent to those skilled in the artly, they are regarded as being included in spirit of the present invention, scope and the content.