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Browse Prior Art Database

High Magnetization Films With Low Eddy Current Losses

IP.com Disclosure Number: IPCOM000042444D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Gambino, RJ: AUTHOR [+2]

Abstract

This improved magnetic material has relatively high saturation magnetization and very low eddy current losses, making it useful for high-frequency magnetic core applications, such as transformers and recording heads. The material comprises alternate layers of crystalline iron (Fe) and an amorphous or microcrystalline iron oxide, such as Fe3O4, which are produced by a pulsed reactive sputtering method. The oxide layers are sufficiently thin to permit exchange coupling of the metallic iron layers, and the thinness of the isolated metallic layers inhibits the flow of substantial eddy currents in these layers around axes parallel to the surface of the layered structure.

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High Magnetization Films With Low Eddy Current Losses

This improved magnetic material has relatively high saturation magnetization and very low eddy current losses, making it useful for high-frequency magnetic core applications, such as transformers and recording heads. The material comprises alternate layers of crystalline iron (Fe) and an amorphous or microcrystalline iron oxide, such as Fe3O4, which are produced by a pulsed reactive sputtering method. The oxide layers are sufficiently thin to permit exchange coupling of the metallic iron layers, and the thinness of the isolated metallic layers inhibits the flow of substantial eddy currents in these layers around axes parallel to the surface of the layered structure. Pulsed reactive sputtering is a continuous sputtering process in which a small volume of a reactive gas is repeatedly introduced into the sputtering chamber during very short time intervals to produce the desired high-resistance layers that insulate the metallic layers from each other. In the exemplary application described herein, an Fe target is sputtered in an inert gas such as argon which at intervals is diluted with pulses of oxygen to produce the insulating layers of Fe3O4 . Each oxygen pulse is produced by opening an automatic control valve for a very short period of time (e.g., one second) to release oxygen under sufficient pressure (about one mTorr) into the argon plasma in the sputtering chamber so that iron oxide is deposited instead of iron during this interval. When the oxygen partial pressure in the chamber drops below a critical value, the deposition of metallic Fe resumes. After a time (e.g., 200 seconds) another oxygen pressure pulse is released into the chamber to cause deposition of an oxide layer, and this process is repeated cyclically. A schemati...