Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
  • G03G5/16—Layers for recording by changing the magnetic properties, e.g. for Curie-point-writing
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C28/00—Alloys based on a metal not provided for in groups C22C5/00 - C22C27/00
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
  • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F10/00—Thin magnetic films, e.g. of one-domain structure
  • H01F10/08—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers
  • H01F10/10—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers characterised by the composition

Definitions

• the magnetization is normal to the film plane.
• This invention relates to ferromagnetic films in general, and ferromagnetic films in particular of the general formula MnAlGe, and in particular MnAlGe films of nonstoichiometric composition and having low Curie point temperatures concurrent with high specific Faraday rotation.
• Potential memory use compositions preferably have room temperature stability, and indeed should be stable over a wide temperature range in air. Further, these films should have a relatively low Curie point, which is also controllable as desired. Further, these films should have a high specific Faraday rotation, be easy to manufacture, and have a sufficient coercivity. The remanent Faraday rotations should also be close to that of saturation. Prior art films have not achieved this.
• a further object is to maintain the Curie point of this material preferably between 180 and 220 C., for use in potential memory applications.
• Still another object of this invention is the ability to make an easily manufactured film by a variety of techniques, the film being stable in air and having the above properties. Further, control of Curie points should be easily obtainable.
• Still another object is to maintain adequate magnetization and coercivity of the film.
• Still another object is a magnetic memory structure employing the ferromagnetic compositions of this invention.
• oxygen may be added to the extent between 0.05-.3 in atomic proportion, for increased stability of the composition.
• non-stoichiometric films of MnAlGe which allow greater control and give the unexpected result of room temperature stability, indeed, stability from room temperature to 400 C., and a lower and controllable Curie point.
• These non-stochiometric films may be produced by RF or DC sputtering, or from vacuum deposition techniques, all of these techniques known in the art.
• the substrate during such deposition techniques is essentially maintained in a temperature range of 25-420f C., while a deposition rate is maintained in the range between 2-10 A. per second in a preferred embodiment. In this manner, films having a composition of Mn Al Ge and optionally, containing oxygen 0.05-.3 are produced.
• These films have a Curie point between 180-220 C., polar Faraday rotations at room temperature of between .75-.9 10 deg./cm., a remanence of greater than .98 of saturation and coercivity of approximately 1500 oersteds.
• the saturation magnetization may be varied between approximately 3000-3600 gauss.
• Example I The composition Mn Al Ge in the form of a film varying from 500-10,000 A., upon a nonmagnetic substrate, exhibited a Curie point of 180 C., a specific Faraday rotation of .75 X 10 deg/cm. coercivity of 1500 oersteds and a saturation magnetization near bulk, or approximately 3000 gauss, the last three values measured at room temperature.
• the Faraday rotation above and those in the following examples are for wavelengths in the visible and near infrared regions.
• Example II The composition Mn Al Ge exhibited a Curie point of 220 C. with a specific Faraday rotation of .9 10 deg./cm., coercivity at 1500 oersteds, and a saturation magnetization of approximately 3600 gauss.
• Example III The addition of between 0.05 and .3 oxygen in atomi proportion, resulting in the formula was added to improve the chemical stability of the material with no detrimental efifect of the magnetic properties as listed above for Mn Al Ge Example IV
• Example V As the aluminum amount increases, the Curie point decreases, but there is a limit to the non-magnetic additions as noted above as aifecting the magnetic properties and stability and crystal structure of the compositions.
• Example VI As manganese increases, so does it become necessary to increase the germanium content, and this in turn increases the Curie temperature close to the bulk value.
• MnAlGe composition having a lower Curie point between the range of 180- 220 C. that is stable between room temperature and substantially 400 C., can be manufactured by a variety of techniques, is stable in air, and has the ease of composition control allowing ease of Curie point control. Further, adequate magnetization and coercivity is achievable for storage applications.
• Mn Al Ge designates a composition having the given atomic proportions of each constituent and not a molecule deficient in atoms.
• Magnetic films are particularly useful for data storage applications, such as in a beam addressable file wherein a polarized beam of light is directed toward the magnetic media and the degree of rotation of the polarization of the beam from the area addressed indicates the state of magnetization of that area.
• the Faraday effect in transmission, or Kerr effect in reflection may be used.
• Beam addressable file configurations are known in the art.
• a film of MnAlGe in the preferred proportions listed above is deposited upon a non-magnetic substrate.
• the substrate may be transparent as may be the film, for the particular wavelength used, or it may be opaque for reflection techniques.
• the substrate may typically be of aluminum or other metals, of a ceramic, or glass. Film thickness is between 50010,000 A.
• the film substrate structure may be in disk form, strip form, drum form or other forms known in the art. Film deposition is by methods known in the art and previously discussed.
• a ferromagnetic composition having a Curie temperature between substantially 180220 C. of a solid solution having atomic proportions indicated by the formula:
• a data storage medium comprising a magnetic film upon a non-magnetic substrate, the magnetic film consisting essentially of a solid solution having atomic proportions indicated by the formula:

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Power Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Hard Magnetic Materials (AREA)
• Thin Magnetic Films (AREA)
• Optical Record Carriers And Manufacture Thereof (AREA)
• Magnetic Record Carriers (AREA)
• Manufacturing Of Magnetic Record Carriers (AREA)
• Physical Vapour Deposition (AREA)

Applications Claiming Priority (1)

Publications (1)

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ID=22750562

Family Applications (1)

Country Status (5)

Cited By (3)

Families Citing this family (4)

• 1971
  • 1971-11-26 US US00202604A patent/US3795541A/en not_active Expired - Lifetime
• 1972
  • 1972-10-05 DE DE19722248839 patent/DE2248839A1/de active Pending
  • 1972-10-18 FR FR7237567A patent/FR2162868A5/fr not_active Expired
  • 1972-10-27 JP JP10728172A patent/JPS5611205B2/ja not_active Expired
  • 1972-11-02 GB GB5045372A patent/GB1396136A/en not_active Expired

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