Electron tunneling device using ferromagnetic thin films
AssigneeMassachusetts Institute of Technology
InventorsJagadeesh S. Moodera, Terrilyn Wong, Lisa Kinder, Robert H. Meservey
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Abstract
Ferromagnetic/insulator/ferromagnetic tunneling has been shown to give over 10% change in the junction resistance with H less than 100 Oe, at room temperature but decreases at high dc-bias across the junction. Using such junctions as magnetic sensors or memory elements would have several advantages; it is a trilayer device and does not strongly depend on the thickness of FM electrodes or the tunnel barrier; submicron size is possible with high junction resistance and low power dissipation. The magnitude of the effect is consistent with the simple model of spin-polarized tunneling between ferromagnets.
Claims36
A device forming a junction having a resistance comprising:
- a first electrode having a first magnetization direction,
- a second electrode having a second magnetization direction, and
- an electrical insulator between the first and the second electrodes, wherein applying a small magnitude of electromagnetic energy to the junction reverses at least one of the magnetization directions and causes a change in the resistance by at least 10% at room temperature.
A memory system comprising a thin film device forming a junction having a resistance comprising:
- a first film layer having a first magnetization direction,
- a second film layer having a second magnetization direction, and
- an electrical insulator film layer placed in between the first and the second film layers, wherein applying a small magnitude of electromagnetic energy to the junction reverses at least one of the magnetization directions and causes a change in the resistance by at least 10% at room temperature.
A method of forming a trilayer tunneling device comprising the steps of:
- cooling a flat smooth substrate surface inside a vacuum evaporation apparatus,
- overlaying a thin seeding layer having relatively high melting point onto the substrate surface,
- overlaying a first ferromagnet layer onto the seeding layer,
- overlaying a precursor film onto the first ferromagnet layer,
- bringing the layers to room temperature and oxidizing the precursor film by a glow discharge in oxygen to form an insulating tunnel barrier layer, and
- overlaying a second ferromagnet layer on the insulating tunnel barrier at room temperature.
A memory device for storing binary data comprising:
- a substrate coated with a thin film comprising a plurality of trilayer devices, each having a junction with a resistance, wherein each device comprises:
- a first film layer having a first magnetization direction,
- a second film layer having a second magnetization direction, and
- an electrical insulator layer between the first and the second film layers, wherein applying a small magnitude of electromagnetic energy to the junction reverses at least one of the magnetization directions and causes a change in the resistance by at least 10% at room temperature.
A memory device for storing binary data comprising:
- a movable read-write sensor head comprising two trilayer devices, each having a junction with a resistance, separated by a gap, wherein each device comprises:
- a first film layer having a first magnetization direction,
- a second film layer having a second magnetization direction, and
- an electrical insulator layer between the first and the second film layers, wherein applying a small magnitude of electromagnetic energy to the junction reverses at least one of the magnetization directions and causes a change in the resistance by at least 10% at room temperature.
A sensor device comprising:
- an integrated circuit comprising a plurality of trilayer devices, each having a junction with a resistance, in a matrix array forming binary bits, wherein each device comprises:
- a first film layer having a first magnetization direction,
- a second film layer having a second magnetization direction, and
- an electrical insulator layer between the first and the second film layers, wherein applying a small magnitude of electromagnetic energy to the junction reverses at least one of the magnetization directions and causes a change in the resistance by at least 10% at room temperature.
Dependencies are inferred from the claim text.