First order transition films for magnetic recording and method of forming |
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| 申请号 | US3607460D | 申请日 | 1968-11-18 | 公开(公告)号 | US3607460A | 公开(公告)日 | 1971-09-21 |
| 申请人 | GEN ELECTRIC; | 发明人 | LOMMEL JAMES M; | ||||
| 摘要 | Thin films of iron-rhodium exhibiting a broadly hysteretic first order transition between the ferromagnetic and antiferromagnetic states are produced by sequentially depositing iron and rhodium films upon a refractory substrate at a pressure in the range of 1 X 10 6 torr, annealing the structure in a vacuum of 1 X 10 6 torr at a temperature of approximately 700* C. for 1 hour to produce a complete diffusion of the iron and rhodium layers, and subsequently subjecting the diffused layers to a second anneal in an atmosphere greater than 10 parts per million oxygen in a thermal cycle that includes slowly heating the structure to 400* C., maintaining the 400* C. for approximately 10 minutes and slowly cooling to room temperature. Films thus formed are advantageously employed in the recording of digital information by electron beam heating individual regions through a first order transition to the ferromagnetic state whereupon the regions are permitted to cool to a biasing temperature slightly higher than the temperature of transition back to an antiferromagnetic state. A magnetic field then is applied to the entire film to magnetize only those regions of the film in the ferromagnetic state and readout of the recorded information can be achieved by conventional electron beam microscopy. The ferromagnetism of the film subsequently can be erased by cooling the film below the transition temperature to the antiferromagnetic state or by the application of a strain to the film. | ||||||
| 权利要求 | 2. A film of iron-rhodium according to claim 1 wherein said film is further characterized by a thermal hysteresis loop having a thermal width between 10* C. and 200* C. at the mean magnetization of said film. 3. A film of iron-rhodium according to claim 1 characterized by the transformation of at least 90 percent of the film from the antiferromagnetic state to the ferromagnetic state upon heating the film to a temperature 70* C. above the critical transition temperature of the film. 4. A film of iron-rhodium according to claim 1 wherein said film is less than 3,000A thick and exhibits a first order transition between the ferromagnetic and antiferromagnetic states in excess of 90 percent of the film when temperature cycled through the thermal hysteresis loop of the film. 5. A film of iron-rhodium and alloys thereof according to claim 4 wherein said film includes less than 10 percent of a metal, codeposited with at least one of said iron and rhodium layers, selected from the group consisting of ruthenium, osmium, iridium, and platinum. 6. A film of iron-rhodium and alloys thereof according to claim 4 wherein said film contains less than 10 atom percent of a metal, codeposited with at least one of said iron and rhodium layers, selected from the group consisting of palladium, vanadium, manganese and gold. 7. A film of iron-rhodium and alloys thereof according to claim 4, wherein said film includes less than 10 atom percent of a metal, deposited as a layer within at least one set of said iron and rhodium layers, selected from the group consisting of ruthenium, osmium, iridium and platinum. 8. A film of iron-rhodium and alloys thereof according to claim 4 wherein said film contains less that 10 atom percent of a metal, deposited as a layer within at least one set of said iron and rhodium layers, selected from the group consisting of palladium, Vanadium, manganese and platinum. |
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