US3714633A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Single and polycrystalline semiconductors
Assignee: Massachusetts Institute of Technology
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Filing: 1970-08-21
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Granted: 1973-01-30
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Expires: 1990-08-21
Abstract
Abstract A class of either single crystal or polycrystalline ferromagnetic materials containing an iron oxide whose resistivity vs. temperature characteristic is such that the resistivity decreased substantially with increasing temperature. The class has non-linear current-voltage (I-V) properties (when employed in electric circuit devices) characterized by a high resistance branch and a negative resistance branch, and the class also exhibits binary characteristics in that devices embodying materials of the class can be made to operate either in a memory state (low resistance) or a normal state (high resistance). The material of the class is prepared by a process which modifies the electrical conductivity of the iron oxide, which is originally highly insulating and also ferromagnetic, to render the material slightly conductive or semiconductive. In the insulating state the oxide contains iron in the trivalent state Fe3 ). The process includes reduction of the iron in the insulating oxide either by heat treating in a vacuum or a controlled atmosphere gas or by doping to reduce some of the trivalent iron (Fe3 ) to bivalent iron (Fe2 ). The material properties are such that when said devices are operated in either the negative resistance branch or in the memory state the ferromagnetic curie point of the material is exceeded and the ordered magnetic properties of the material are locally destroyed. The local destruction can be sensed optically or by other means. The materials of the class disclosed may be used simply in conductive devices, but they can also be used in apparatus, as, for example, the matrices discussed hereinafter, which employ their multi-faceted electrical characteristics as well as their magnetic properties. Materials, which exhibit characteristics of the high resistance branch and the negative resistance branch and are ferroelectric, are also disclosed, as are, also, iron oxide materials which exhibit such characteristics and are neither ferromagnetic nor ferroelectric.
Inventors
- 👤 D Epstein
- 👤 D Bullock
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 06:01
CPC Classifications
G; G11; G11C; G11C11/00; G11C11/21; G11C11/22; G11C11/34; G11C11/39; G11C16/00; G11C16/02; G11C16/04; G11C16/0466; H; H01; H01C; H01C7/00; H01C7/04; H01C7/042; H01C7/043; H01C7/046; H01F; H01F10/00; H01F10/06; H10; H10B; H10B63/00; H10B63/80; H10B63/82; H10N; H10N70/00; H10N70/011; H10N70/041; H10N70/20; H10N70/801; H10N70/881; H10N70/883; H10N70/8836; G11C2211/00; G11C2211/56; G11C2211/561; G11C2211/5614
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
93 words
A matrix comprising, in combination, a thin plate single crystal or polycrystalline semiconducting magnetic orthoferrite material capable of supporting magnetic bubbles and which has non-linear current-voltage properties characterized by a high resistance branch and a negative resistance branch, a plurality of conductors secured as a grid at one surface of the plate, a plurality of further conductors secured as a grid at the other surface of the plate, and a source of electric potential connected to introduce a voltage between conductors at said one plate surface and conductors at said other plate surface.
Claim 2
Dependent Claim
93 words
A matrix comprising, in combination, a thin plate single crystal or polycrystalline semiconducting magnetic orthoferrite material capable of supporting magnetic bubbles and which has non-linear current-voltage properties characterized by a high resistance branch and a negative resistance branch, a plurality of conductors secured as a grid at one surface of the plate, a plurality of further conductors secured as a grid at the other surface of the plate, and a source of electric potential connected to introduce a voltage between conductors at said one plate surface and conductors at said other plate surface.
Claim 3
Dependent Claim
134 words
Apparatus as claimed in claim 1 in which said material is one that also exhibits binary properties whereby regions of the plate can be placed in either a high electrical resistance normal state or a low electrical resistance memory state, the material being such that, when in the normal state, it can be switched to the memory state by applying between a conductor at said one plate surface and a conductor at said other plate surface an electric switching potential that exceeds a threshold voltage of the material in the region between the conductors and when the apparatus is the memory state it can be switched to the normal state by passing an electric current through said region from a conductor at said one plate surface and a conductor at the other plate surface.
Claim 4
Dependent Claim
26 words
Apparatus as claimed in claim 2 that further includes a source of electric potential connected to said conductors to energize the conductors in a determined pattern.
Claim 5
Dependent Claim
139 words
A matrix comprising, in combination, a thin plate single or polycryalline ferromagnetic iron-oxide material having a non-linear current vs. voltage characteristic which includes a high resistance branch and a negative resistance branch and in which the transition point therebetween can be controlled by effectinG changes in the concentration of cations of the iron in the iron oxide, said iron oxide having an electrical resistance which decreases substantially with increasing temperature within the range of temperatures to which such materials are subjected in operating devices, a plurality of electrical conductors secured as a grid at one surface of the plate, a plurality of further electrical conductors secured as a grid at the other surface of the plate, and a source of electric potential connected to introduce a voltage between conductors at said one surface and conductors at said other surface.
Claim 6
Dependent Claim
139 words
A matrix comprising, in combination, a thin plate single or polycryalline ferromagnetic iron-oxide material having a non-linear current vs. voltage characteristic which includes a high resistance branch and a negative resistance branch and in which the transition point therebetween can be controlled by effectinG changes in the concentration of cations of the iron in the iron oxide, said iron oxide having an electrical resistance which decreases substantially with increasing temperature within the range of temperatures to which such materials are subjected in operating devices, a plurality of electrical conductors secured as a grid at one surface of the plate, a plurality of further electrical conductors secured as a grid at the other surface of the plate, and a source of electric potential connected to introduce a voltage between conductors at said one surface and conductors at said other surface.
Claim 7
Dependent Claim
41 words
A matrix as claimed in claim 4 in which said material is one which also exhibits binary properties whereby regions of the plate can be placed in either a high electrical resistance normal state or a low electrical resistance memory state.
Claim 8
Dependent Claim
158 words
A matrix comprising, in combination, a thin plate single or polycrystalline ferromagnetic iron-oxide material which exhibits binary properties whereby regions of the plate can be placed in either a high electrical resistance normal state or a low electrical resistance memory state, the curie point of the material being exceeded in the memory state to destroy ordered properties which exist in the normal state, said iron oxide having an electrical resistance which decreases substantially with increasing temperature within the operating temperature range, a plurality of electrical conductors secured as a grid at one surface of the plate, a plurality of further electrical conductors secured as a grid at the other surface of the plate, and a source of electric potential connected to introduce a voltage between conductors at said one surface and conductors at said other surface to create as alternate conditions the normal state and the memory state wherein the memory state the ordered magnetic properties are destroyed.
Claim 9
Dependent Claim
158 words
A matrix comprising, in combination, a thin plate single or polycrystalline ferromagnetic iron-oxide material which exhibits binary properties whereby regions of the plate can be placed in either a high electrical resistance normal state or a low electrical resistance memory state, the curie point of the material being exceeded in the memory state to destroy ordered properties which exist in the normal state, said iron oxide having an electrical resistance which decreases substantially with increasing temperature within the operating temperature range, a plurality of electrical conductors secured as a grid at one surface of the plate, a plurality of further electrical conductors secured as a grid at the other surface of the plate, and a source of electric potential connected to introduce a voltage between conductors at said one surface and conductors at said other surface to create as alternate conditions the normal state and the memory state wherein the memory state the ordered magnetic properties are destroyed.
Claim 10
Independent Claim
173 words
A device comprising, in combination, a thin plate of semiconducting magnetic material capable of supporting magnetic bubbles, said material having non-linear current vs. voltage bulk-material properties characterized by a high resistance branch and a negative resistance branch, electrical conductor means electrically connected to each surface of the plate and adapted to receive an electric potential to create an electric current through the plate between a conductor at one surface of the plate and a conductor at the other surface thereof, said electrical conductor means comprising a plurality of electrical conductors electrically connected to each surface of the plate in a matrix form, thereby to allow the creation of magnetic bubbles randomly within said plate, a bubble occurring in the material when it is magnetized to saturation and an electric current is passed through the plate from a conductor at one surface thereof to a conductor at the other surface thereof of sufficient magnitude to heat a local region of the material therebetween above the curie point locally destroying the ordered magnetic properties thereof.
Claim 11
Independent Claim
173 words
A device comprising, in combination, a thin plate of semiconducting magnetic material capable of supporting magnetic bubbles, said material having non-linear current vs. voltage bulk-material properties characterized by a high resistance branch and a negative resistance branch, electrical conductor means electrically connected to each surface of the plate and adapted to receive an electric potential to create an electric current through the plate between a conductor at one surface of the plate and a conductor at the other surface thereof, said electrical conductor means comprising a plurality of electrical conductors electrically connected to each surface of the plate in a matrix form, thereby to allow the creation of magnetic bubbles randomly within said plate, a bubble occurring in the material when it is magnetized to saturation and an electric current is passed through the plate from a conductor at one surface thereof to a conductor at the other surface thereof of sufficient magnitude to heat a local region of the material therebetween above the curie point locally destroying the ordered magnetic properties thereof.
Claim 12
Dependent Claim
56 words
Apparatus as claimed in claim 7 that includes a source of electric potential connected to said conductors, the voltage output of said source being sufficient in magnitude to place the material between energized conductors in the negative resistance branch, thereby exceeding the magnetic curie point of the material locally destroying the magnetic properties of the material.
Claim 13
Dependent Claim
34 words
Apparatus as claimed in claim 8 that further includes means for applying a magnetic field in a direction normal to the plane of the plate and of sufficient magnitude magnetically to saturate the plate.
Claim 14
Dependent Claim
157 words
Apparatus as claimed in claim 9 in which said material is one that also exhibits binary properties whereby regions of the plate can be placed in either a high electrical resistance normal state or a low electrical resistance memory state, the material being such that, when in the normal state, it can be switched to the memory state by applying between a conductor at said one plate surface and a conductor at said other plate sUrface an electric switching potential that exceeds a threshold voltage of the material in the region between the conductors and when the apparatus is in the memory state it can be switched to the normal state by passing an electric current through said region from a conductor at said one plate surface to a conductor at the other plate surface, a bubble being created in the material when the material is magnetized to saturation and is then switched to the memory state.
Claim 15
Dependent Claim
51 words
Apparatus as claimed in claim 10 which includes an electric potential means connected to said conductors and adapted to cause the apparatus at said region to generate one of the high resistance branch, the negative resistance branch, the memory state, and the normal state as successive or alternate conditions of operation.
Claim 16
Dependent Claim
44 words
Apparatus as claimed in claim 10 in which said material is chosen from the group consisting of orthoferrites, spinels, garnets, and perovskites in which the oxide is reduced to change the valence state of a cation thereby to provide said non-linear and/or binary characteristics.
Claim 17
Dependent Claim
24 words
Apparatus as claimed in claim 12 in which the material includes a dopant to effect the change in the valance state of the cations.
Claim 18
Dependent Claim
27 words
Apparatus as claimed in claim 13 in which the material is yttrium-iron-garnet and in which the dopant is silicon in amounts from about 0.005 to 0.3 percent.
Claim 19
Dependent Claim
45 words
Apparatus as claimed in claim 10 in which the material is oxide material and is selected from the group consisting essentially of KTaO3, KxNa1 xTaO3, KNbO3, KTaxNb1 xO3, BaTiO3, BaxSr1 xTiO3, where x varies from zero to one in each instance, and compounds derived therefrom.
Claim 20
Dependent Claim
58 words
Apparatus as claimed in claim 15 and in which the material contains predetermined small amounts of a dopant adapted to affect said concentration of a cations, the dopant being one that enters substitutionally into the lattice of the crystal and one that has a valence state either greater than or less than the valence state of the domination.
Claim 21
Dependent Claim
40 words
Apparatus as claimed in claim 10 in which the material is an oxide material and is selected from the group consisting essentially of the compounds YFeO3, TbFeO3, NiFe2O4, FeFe2O4, MgFe2O4, MnFe2O4, and CoFe2O4 plus various solid solutions of the compounds.
Claim 22
Dependent Claim
34 words
Apparatus as claimed in claim 17 in which the oxide material contains a dopant to reduce the oxide thereby to change the valence state of a cation thereof to provide the required resistance characteristics.
Claim 23
Dependent Claim
163 words
A matrix comprising, in combination, a thin plate single or polycrystalline oxide magnetic material wafer which also exhibits binary electric properties whereby regions of the plate can be placed in either a high electric resistance normal state or a low electric resistance memory state, said material having an electrical resistance which decreases substantially with increasing temperature within the operating temperature range, a plurality of electrical conductors secured as a grid at one surface of the plate, a plurality of further electrical conductors secured as a grid at the other surface of the plate, said conductors being adapted to receive an electric switching potential between a conductor at one surface of the plate and a conductor at the other surface of the plate that exceeds a threshold voltage of the oxide material, thereby to pass an electric current in the form of pulse through the plate from one electrode to the other to create as alternate condition the normal state and the memory state.
Claim 24
Dependent Claim
163 words
A matrix comprising, in combination, a thin plate single or polycrystalline oxide magnetic material wafer which also exhibits binary electric properties whereby regions of the plate can be placed in either a high electric resistance normal state or a low electric resistance memory state, said material having an electrical resistance which decreases substantially with increasing temperature within the operating temperature range, a plurality of electrical conductors secured as a grid at one surface of the plate, a plurality of further electrical conductors secured as a grid at the other surface of the plate, said conductors being adapted to receive an electric switching potential between a conductor at one surface of the plate and a conductor at the other surface of the plate that exceeds a threshold voltage of the oxide material, thereby to pass an electric current in the form of pulse through the plate from one electrode to the other to create as alternate condition the normal state and the memory state.
Claim 25
Dependent Claim
18 words
Apparatus as claimed in claim 19 that further includes a source of electric potential connected across said conductors.
Claim 26
Independent Claim
158 words
A method of creating a magnetic bubble at any one of a number of regions of a thin film iron-oxide semiconductive garnet or a spinel oR an orthoferrite single or polycrystalline matrix device which is also magnetic and which also exhibits binary and/or non-linear electric characteristics, which regions of the thin film matrix can be placed in a high electrical resistance normal state or a low resistance memory state, or a high resistance branch or a negative resistance branch, that comprises: magnetizing the film to saturation in the thickness direction when the region is in either the normal state or the high resistance branch and applying across said film at each region of the matrix at which a bubble is to be created an electric switching potential that exceeds a threshold voltage of the film to switch the device to either the memory state or the negative resistance branch, thereby creating a magnetic bubble at each said region.
Claim 27
Independent Claim
158 words
A method of creating a magnetic bubble at any one of a number of regions of a thin film iron-oxide semiconductive garnet or a spinel oR an orthoferrite single or polycrystalline matrix device which is also magnetic and which also exhibits binary and/or non-linear electric characteristics, which regions of the thin film matrix can be placed in a high electrical resistance normal state or a low resistance memory state, or a high resistance branch or a negative resistance branch, that comprises: magnetizing the film to saturation in the thickness direction when the region is in either the normal state or the high resistance branch and applying across said film at each region of the matrix at which a bubble is to be created an electric switching potential that exceeds a threshold voltage of the film to switch the device to either the memory state or the negative resistance branch, thereby creating a magnetic bubble at each said region.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-30 | 1976-07-31 | 1977-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-30 | 1980-07-31 | 1981-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-30 | 1984-07-31 | 1985-01-30 | $7700.00 | Window Closed / Lapsed |