Magnetic oscillator
| Title: | Magnetic oscillator |
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| Patent Number: | 8,553,372 |
| Publication Date: | October 08, 2013 |
| Appl. No: | 13/430074 |
| Application Filed: | March 26, 2012 |
| Abstract: | According to one embodiment, a magnetic oscillator includes a layered film and a pair of electrodes. The layered film includes a first ferromagnetic layer, an insulating layer stacked on the first ferromagnetic layer, and a second ferromagnetic layer stacked on the insulating layer. The pair of electrodes is configured to apply a current to the layered film in a direction perpendicular to a film surface of the layered film. Regions having different resistance area products are provided between the first ferromagnetic layer and the second ferromagnetic layer. |
| Inventors: | Nagasawa, Tazumi (Yokohama, JP); Kudo, Kiwamu (Kamakura, JP); Sato, Rie (Yokohama, JP); Mizushima, Koichi (Kamakura, JP) |
| Assignees: | Kabushiki Kaisha Toshiba (Minato-ku, Tokyo, JP) |
| Claim: | 1. A magnetic oscillator comprising: a layered film comprising a first ferromagnetic layer, an insulating layer stacked on the first ferromagnetic layer, and a second ferromagnetic layer stacked on the insulating layer; and a pair of electrodes configured to apply a current to the layered film in a direction perpendicular to a film surface of the layered film; wherein regions having different resistance area products are provided between the first ferromagnetic layer and the second ferromagnetic layer, wherein each of the first ferromagnetic layer, the insulating layer, the second ferromagnetic layer has a cross sectional shape taken along a plane perpendicular to a stacking direction, the cross sectional shape being tapered toward an end part, and the insulating layer is provided with a leak path in the end part, the leak path having a smaller resistance area product than a resistance area product of the insulating layer. |
| Claim: | 2. The oscillator according to claim 1 , wherein the insulating layer includes the regions having different thicknesses. |
| Claim: | 3. The oscillator according to claim 1 , further comprising a metal path which electrically connects the first ferromagnetic layer and the second ferromagnetic layer. |
| Claim: | 4. A magnetic recording and reproducing apparatus comprising: a magnetic oscillator comprising a layered film and a pair of electrodes, the layered film comprising a first ferromagnetic layer, an insulating layer stacked on the first ferromagnetic layer, and a second ferromagnetic layer stacked on the insulating layer, the pair of electrodes configured to apply a current to the layered film in a direction perpendicular to a film surface of the layered film, wherein regions having different resistance area products are provided between the first ferromagnetic layer and the second ferromagnetic layer, and wherein each of the first ferromagnetic layer, the insulating layer, the second ferromagnetic layer has a cross sectional shape taken along a plane perpendicular to a stacking direction, the cross sectional shape being tapered toward an end part, and the insulating layer is provided with a leak path in the end part, the leak path having a smaller resistance area product than a resistance area product of the insulating layer. |
| Claim: | 5. The apparatus according to claim 4 , wherein the insulating layer includes the regions having different thicknesses. |
| Claim: | 6. The apparatus according to claim 4 , further comprising a metal path which electrically connects the first ferromagnetic layer and the second ferromagnetic layer. |
| Claim: | 7. A magnetic oscillator comprising: a layered film comprising a first ferromagnetic layer, an insulating layer stacked on the first ferromagnetic layer, and a second ferromagnetic layer stacked on the insulating layer; and a pair of electrodes configured to apply a current to the layered film in a direction perpendicular to a film surface of the layered film; wherein regions having different resistance area products are provided between the first ferromagnetic layer and the second ferromagnetic layer, wherein the insulating layer includes the regions having different thicknesses, and wherein an end part of the insulating layer has a greater thickness than another part of the insulating layer. |
| Claim: | 8. The oscillator according to claim 7 , further comprising a metal path which electrically connects the first ferromagnetic layer and the second ferromagnetic layer. |
| Claim: | 9. A magnetic recording and reproducing apparatus comprising: a magnetic oscillator comprising a layered film and a pair of electrodes, the layered film comprising a first ferromagnetic layer, an insulating layer stacked on the first ferromagnetic layer, and a second ferromagnetic layer stacked on the insulating layer, the pair of electrodes configured to apply a current to the layered film in a direction perpendicular to a film surface of the layered film, wherein regions having different resistance area products are provided between the first ferromagnetic layer and the second ferromagnetic layer, wherein the insulating layer includes the regions having different thicknesses, and wherein an end part of the insulating layer has a greater thickness than another part of the insulating layer. |
| Claim: | 10. The apparatus according to claim 9 , further comprising a metal path which electrically connects the first ferromagnetic layer and the second ferromagnetic layer. |
| Claim: | 11. A magnetic oscillator comprising: a layered film comprising a first ferromagnetic layer, an insulating layer stacked on the first ferromagnetic layer, and a second ferromagnetic layer stacked on the insulating layer; and a pair of electrodes configured to apply a current to the layered film in a direction perpendicular to a film surface of the layered film; wherein regions having different resistance area products are provided between the first ferromagnetic layer and the second ferromagnetic layer, and wherein the resistance area products comprise a resistance per unit area in a plane perpendicular to a direction of flow of current. |
| Claim: | 12. The oscillator according to claim 11 , wherein the insulating layer includes the regions having different thicknesses. |
| Claim: | 13. The oscillator according to claim 11 , further comprising a metal path which electrically connects the first ferromagnetic layer and the second ferromagnetic layer. |
| Claim: | 14. A magnetic recording and reproducing apparatus comprising: a magnetic oscillator comprising a layered film and a pair of electrodes, the layered film comprising a first ferromagnetic layer, an insulating layer stacked on the first ferromagnetic layer, and a second ferromagnetic layer stacked on the insulating layer, the pair of electrodes configured to apply a current to the layered film in a direction perpendicular to a film surface of the layered film, wherein regions having different resistance area products are provided between the first ferromagnetic layer and the second ferromagnetic layer, and wherein the resistance area products comprise a resistance per unit area in a plane perpendicular to a direction of flow of current. |
| Claim: | 15. The apparatus according to claim 14 , wherein the insulating layer includes the regions having different thicknesses. |
| Claim: | 16. The apparatus according to claim 14 , further comprising a metal path which electrically connects the first ferromagnetic layer and the second ferromagnetic layer. |
| Current U.S. Class: | 3603/242 |
| Patent References Cited: | 5966012 October 1999 Parkin 6005753 December 1999 Fontana et al. 7602588 October 2009 Sato et al. 7667933 February 2010 Kudo et al. 8063709 November 2011 Firastrau et al. 8198919 June 2012 Kozhanov et al. 2002/0114111 August 2002 Zhu 2002/0149886 October 2002 Gill 2006/0056114 March 2006 Fukumoto et al. 2009/0201614 August 2009 Kudo et al. 2010/0039181 February 2010 Firastrau et al. 2011/0007431 January 2011 Braganca et al. 2012/0154063 June 2012 Nikonov et al. 2006-286855 October 2006 2006-295908 October 2006 2008-311373 December 2008 2009-135471 June 2009 2009-194070 August 2009 |
| Other References: | Kaka, et al; “Mutual Phase-Locking of Microwave Spin Torque Nano-Oscillators”; Nature Letters; vol. 437, Sep. 15, 2005; doi:10.1038/nature04035; pp. 389-392. cited by applicant Rippard, et al.; “Current-Driven Microwave Dynamics in Magnetic Point Contacts as a Function of Applied Field Angle”; Sep. 27, 2004; Physical Review B 70, 100406(R); Rapid Communications; pp. 100406-1-100406-4. cited by applicant Kiselev; et al.; “Microwave Oscillations of a Nanomagnet Driven by a Spin-Polarized Current”; Nature, vol. 425, Sep. 25, 2003; pp. 380-383. cited by applicant International Search Report dated Dec. 22, 2009 from PCT/JP2009/066970. cited by applicant |
| Primary Examiner: | Cao, Allen T |
| Attorney, Agent or Firm: | Ohlandt, Greeley, Ruggiero & Perle, L.L.P. |
| Accession Number: | edspgr.08553372 |
| Database: | USPTO Patent Grants |
| Language: | English |
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