Method of forming a magnetic material for recording information with high density

H01F10/08 - characterised by magnetic layers (applying magnetic films to substrates H01F0041140000)
G11B5/714 -

 

(57) Abstract:

The invention relates to the field of electrical engineering, in particular to methods for magnetic media for recording information with high density. The essence of the method is that in the process of forming the magnetic matrix representing the magnetic tape, is entered into the field with different matrix magnetic state, which have dimensions in the range from several angstroms to 50 nm and are formed as a result of the introduction of the magnetic matrix impurities or defects in the crystal structure. The technical result of the invention is to provide a magnetic recording medium of high density, as well as simplifying the process of obtaining such material. 6 C.p. f-crystals.

The invention relates to methods for magnetic media for high-density recording of information. The main application of the invention can be when creating magnetic media high capacity, used in magnetic and magneto-optical recording.

Currently, for storing digital information used magnetic disks, for which on the non-magnetic substrate is coated with a layer of magnetic material on which prokritee, containing single-domain magnetic particles (typically Fe2ABOUT3) or thin (thickness of 50-150 nm) film of a magnetic metal, alloy or oxide (commonly used alloys based on Co, such as Co-Ni, Co-Ni-W, Co-Pt-Ni, and so on). The size of the magnetic particles is about 100 nm. Thin magnetic films have a granular structure with a grain size of the order of the film thickness. The coercive force of magnetic materials for information storage, lies in the range from 700 to 3000 e, and the residual induction reaches 15000 G [1].

The problem of increasing areal density while maintaining acceptable signal-to-noise ratio requires reducing the size of magnetic particles or grains in the film to the size of the order of 10 nm and below, which in itself is a difficult technological task. However, reducing the size of particles and grains can lead to instability of the recorded signal due to the effects of thermal vibrations of the crystal lattice or matrix on the magnetic moment of the grain or particle. In thin films, which is today the main media for magnetic recording of digital information, this effect will increase as a result of exposure to grain demagnetizing fields of the neighboring C is and should be used to obtain films of magnetic materials with anisotropy, greater than the materials being used today. Signal-to-noise ratio significantly degraded also due to the interaction between neighboring grains in the film resulting from their close mutual arrangement.

To solve these problems and obtain a medium for magnetic recording with high performance in U.S. patent No. 6183606 has been proposed a method of obtaining a composite granular thin films containing grain vysokokoertsitivnye FePt alloy in the insulating non-magnetic matrix Si3N4. The film was produced by combining vacuum magnetron sputtering targets of the FePt alloy of a given composition and Si3N4on a cooled substrate and silicon dioxide or quartz glass. For translation of the FePt alloy in vysokopitatelny crystalline phase of the film was annealed in order in a vacuum at a temperature of 600C followed by quenching in water at 0C. This method has allowed us to create a film with the axis of easy magnetization lying in the plane of the film, the coercive force of ~ 4000 OE and a grain size of several tens nm. A sufficiently large distance between the grains and the presence of a layer of insulating non-magnetic material between them prevents interaction between kontroliruemyi technological process of manufacture of the film and the relatively large size of the magnetic grain.

In U.S. patent No. 6214434 method of obtaining environment for high-density magnetic recording, which consists in forming on the surface of the layer of nonmagnetic material (Cr, Si, non-magnetic metals and non-magnetic non-metals) deposited on a nonmagnetic substrate (NiP, Al, glass, ceramics and so on), recesses and then applying by chemical vapor deposition or spraying) in these grooves magnetic metal (Ni, Co, magnetic alloys). Deepening diameter of about 100 nm and a depth of 50 nm were located at a distance of 200 nm from each other. Formed recesses by means of thermal action of laser radiation, podwodnego to the selected point on the surface of the nonmagnetic matrix volokonnoopticheskimi fiber. Magnetic material that was after deposition outside of the recesses on the surface of the nonmagnetic layer was removed by mechanical grinding. Depressions filled with a magnetic material represented noninteracting, regularly spaced insulated magnetic particles, which may be magnetic recording. The disadvantages of this method are fairly complicated process, involving many intermediate stages, and relatively large size sformirovannosti formed nanosized magnetic particles.

The present invention enables to obtain a magnetic medium for recording high density, and also to simplify the process of obtaining magnetic media for recording.

This task is solved in that the objects on which the record information and which is an integral component of magnetic media for recording, it is proposed to use nanoscale region (clusters) are different from the main matrix of the magnetic state, resulting from the introduction of the matrix impurities or defects. Impurities or defects are introduced in the magnetic matrix representing the film directly in the process of its formation and spread it evenly.

A feature of the invention is that in the process of receiving environment to store information in the original matrix of magnetic material are introduced impurities or defects. Introduced impurities or defects interact with the matrix material, resulting in:

1) formed therein fine areas (clusters) with a characteristic size from a few angstroms to several tens of nanometers and significantly different from the main matrix type magnetic state of the magnetic state of ha is AI, demagnetizing factor, other magnetic characteristics, as well as their combination);

2) clusters steadily fixed in the matrix at the positions associated with the spatial location of impurities or defects (on the impurities or defects or in different points of space between them, for example in the interstices). While impurities and defects are uniformly distributed in the matrix material. Clusters, on which record information can be located in the matrix are statistically evenly or to form an ordered spatial structure.

As the original matrix used material with ferro-and antiferromagnetic or any other type of magnetic ordering or paramagnetic properties. Cluster characteristics (size, distance between clusters and their spatial arrangement, magnetic state, and so on) are determined by the physical properties of the matrix and type impurities (or defects) and can be adjusted within wide limits by changing the concentration of impurities or defects, which can be up to 30 at.%. The magnetic state of the cluster is different from the magnetic condition of the matrix: for example, it can be ferrone is (Be), boron (B), carbon (C), sodium (Na), magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), potassium (K), calcium (CA), elements of 3d transition groups: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn; gallium (Ga), germanium (Ge), arsenic (As), selenium (Se), bromine (Br), rubidium (Rb), strontium (Sr), the elements of the 4d transition group: Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, cesium (Cs), barium (BA), elements 4f transition group (rare earth elements): La, CE, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; elements 5d transition group: Hf, TA, W, Re, Os, Ir, Pt, Au; lead (Pb), or combinations thereof, as well as defects - vacancies, atoms implementation, the local stress heterogeneity, displacement, dislocation, distortion, and other violations of the periodicity of the crystal lattice or a combination of both.

The claimed method of forming a magnetic medium for recording information can be performed using known methods of obtaining thin films, which include:

chemical and electrochemical deposition from the liquid phase;

chemical vapor deposition;

- vacuum deposition;

molecular-beam epitaxy;

- ion-beam sputtering;

- vacuum sputtering for direct or alternating current;

- magnetron sputtering;

- pulse/P>The required stoichiometry matrix and the content of impurities and defects is provided by selecting an appropriate composition of targets, electrodes, solutions, atmospheric composition, temperature, pressure, electromagnetic fields and other adjustable parameters during the process of forming the film. The introduction of defects and changes in their concentrations can be controlled by irradiation of the matrix in the process of its formation or subsequent processing of high-energy photons, ions, electrons and other particles. For introduction into the matrix impurities or defects is also used by the deposition of the film matrix on the sublayer containing a given concentration of impurities or providing their structure formation of defects. Properties obtained by the above methods of recording can also be changed by heat treatment (annealing, hardening, and so on) in a vacuum or in a gas atmosphere (atmosphere may contain gases such as nitrogen, oxygen, hydrogen, argon, and so on), causing the recrystallization or other changes of the crystalline structure of the matrix and the distribution of impurities or defects, and choice of treatment mode.

The possibility to receive their interaction with the matrix. The last factor network required for recording on the magnetic material hysteresis properties of the coercive force and residual magnetization. In fact, the proposed method allows to obtain a magnetic medium for recording the same media consisting of a nonmagnetic polymer film includes submicron magnetic particles discussed above (analogous to the magnetic submicron particles are used in this case nanoscale clusters with different from the main matrix type magnetic ordering). However, the environment obtained by the proposed method, are characterized by significant reduction in size of magnetic clusters and their intense magnetic interaction with the matrix, leading to increased anisotropic properties and reduce the effect of thermal vibrations of the crystal lattice on the magnetic moment of the cluster. All this allows to increase the reliability of information storage, significantly increase the recording density.

The following example illustrates but does not limit the essence of the invention.

Film Laof 0.85CAof 0.15MnO3(the original matrix LaMnO3the impurity - Sa) is a method of sputtering of the corresponding SV vacuum chamber and focused onto the target surface. As a result of heating by the beam of the target material it evaporates. The evaporated ions are deposited on the button in the cell substrate, forming therein a thin film of a given composition. The substrate is heated to increase the mobility of adsorbed atoms and reaching equilibrium crystalline structure of the film.

The target is prepared by ceramic technology by mixing rare earth oxide La2O3and carbonates of caso3and MPMs3their milling and sintering at a temperature of 1400C for 24 hours followed by annealing at 1000C for 8 hours (sintering and annealing are carried out in oxygen atmosphere).

To obtain the film Laof 0.85CAof 0.15MnO3a thickness of 100 nm is used KrF excimer laser with a wavelength of 248 nm, pulse energy of 0.5 j, pulse duration of 15 NS and a pulse repetition rate of 30 Hz. The distance between the substrate and the target is 40 mm In the process of forming the film in the camera is supported by the oxygen pressure value of 0.1 Torr. The temperature of the substrate is 700C. the Substrate is an oxidized silicon wafer.

Crystal structure of the film is controlled with rentgenologiia. Hysteresis loops measured with a vibrating sample magnetometer at the temperature of liquid nitrogen, are characterized by a coercive force value 650 e and the residual magnetization value of 250 GS. Curves of the magnetization on the temperature measured at the cooling in the presence of a magnetic field and without the field, find a significant temperature hysteresis below the point of the magnetic ordering. On the temperature dependence of the magnetization obtained when cooled without fields, there is also a sharp decline at low temperatures. This behavior is typical for a system of noninteracting ferromagnetic particles (clusters) in the matrix, and indicates the possibility of applying film manufactured by the method described above, for high-density magnetic recording.

The lanthanum manganite LaMn3has the crystal structure of perovskite and is an insulator with antiferromagnetic ordering. In accordance with model representations [2, 3], the introduction of lanthanum manganite divalent impurity element (such as CA or Sr), causes the formation near the atoms of clusters nanometrovomu size with ferromagnetic ordering. Source matrices measurement, conducted on samples of lanthanum manganite doped with calcium La1-xCAxMnO3(x=0,05; 0,08) [4], showed that the cluster size in the antiferromagnetic matrix is about 1 nm. The increase of impurity concentration causes an increase of the cluster size. In the single crystal of La0,7CAfor 0.3MnO3using a scanning tunneling microscope were detected ferromagnetic clusters with sizes of a few tens of nm [5]. In otomanguean on the basis of rare earth elements with the impurity content of the divalent element to 30% (RaMn3R - rare earth metal La, Eu, WG, Nd, a bivalent element of CA, BA, Sr) observed magnetic behavior for systems of noninteracting magnetic particles in the matrix, in particular, a strong temperature hysteresis on the dependencies of the magnetization on the temperature measured at the cooling in the presence of a magnetic field and without the field.

Thus, the proposed in this patent is a method of obtaining environment for high-density magnetic recording can be realized, in particular, thin films based on rare-earth artamanov with perovskite structure.

Sources of information

1. Materikov L. P. Successes of the physical Sciences, 1998, I. 168, No. 6, 665-671.

4. Hennion M., Moussa F., G. Biotteau, Rodriguez-Carvajal J., L. Pinsard, And A. Revcolevschi - Phys. Rev. Letters, 1998, v. 81, No. 9, 1957-1960.

5. Fath, M., S. Freisem, A. A. Menovsky, Y. Tomioka, J. Aarts, J. A. Mydosh - Science, 1999, v. 285, 1540-1542.

1. Method of forming a magnetic material for recording information with high density, including the formation of the matrix representing the film, other than the matrix of the magnetic state in the process, characterized in that the matrix is made of magnetic material, and areas with different matrix magnetic state have dimensions in the range from several angstroms to 50 nm and are formed as a result of the introduction of the magnetic matrix impurities or defects in the crystal structure.

2. The method of forming the magnetic material under item 1, characterized in that as impurities are used, Be, b, C, Na, mg, Al, Si, P, K, CA, elements of 3d transition groups: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, elements of 4d transition group: Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Cs, BA, elements 4f transition group - rare earth elements: La, CE, WG, Nd, Pm, Sm, Eu, Gd, Tb, Dy, But, Er, Tm, Yb, Lu; elements 5d transition group: Hf, TA, W, Re, Ir, Pt, Au, Pb or a combination of both.

3. Method of forming magnetic marazene, heterogeneity, displacement, dislocation, distortion, and other violations of the periodicity of the crystal lattice or a combination of both.

4. The method of forming the magnetic material under item 1, characterized in that in the method of producing the magnetic material used in chemical and electrochemical deposition from the liquid phase, chemical vapor deposition, vacuum deposition, molecular beam epitaxy, ion beam sputtering, vacuum sputtering on DC or AC magnetron sputtering, pulsed laser sputtering.

5. The method of forming the magnetic material under item 1, characterized in that the obtained magnetic material is subjected to a heat treatment in vacuum or in a gas atmosphere, causing the recrystallization or other changes of the crystalline structure of the magnetic matrix and the distribution of impurities or defects.

6. The method of forming the magnetic material under item 1, characterized in that for the introduction of a magnetic matrix defects and changes in their concentration of magnetic material is exposed during formation or after irradiation of high-energy photons, ions, electrons and other particles.

7. SPO is or defects is used, the deposition film magnetic matrix on the underlayer, containing a given concentration of impurities or providing their structure formation of defects.

 

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