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High Magnetic Field Measuring Devices

IP.com Disclosure Number: IPCOM000095983D
Original Publication Date: 1964-Nov-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Suits, JC: AUTHOR

Abstract

A device for measuring a high magnetic field 10 at temperatures at least as low as 4. 2 degrees K utilizes the magneto-resistance of a composite material 12. Regions A of material 12 are grains of semi-conducting ferromagnetic and magnetostrictive material of relatively low resistivity. Regions B are very thin intergranular regions of high resistivity, such as a second phase precipitate or cracks.

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High Magnetic Field Measuring Devices

A device for measuring a high magnetic field 10 at temperatures at least as low as 4. 2 degrees K utilizes the magneto-resistance of a composite material 12. Regions A of material 12 are grains of semi-conducting ferromagnetic and magnetostrictive material of relatively low resistivity. Regions B are very thin intergranular regions of high resistivity, such as a second phase precipitate or cracks.

When a potential is applied by voltage source 14 across material 12, tunneling occurs across regions B. The tunneling current is extremely sensitive to small changes in the dimensions of regions A. The application of magnetic field 10 to material 12 near the Curie temperature results in a large change in the resistance of material 12. The material used for regions A can be, e. g., suitably prepared or doped europium selenide, europium sulfide or europium oxide. The material of regions B can be, e. g., undoped europium oxide. Gadolinium can be used as the dopant for producing the low resistivity semiconducting material.

Alternatively, regions B can be made of a material of high piezoresistance. When the latter type material is used, the operation of the device depends directly upon the stress applied to regions B rather than upon tunneling and actual changes in the dimensions of regions B.

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