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Amorphous Ferromagnetic Alloys

IP.com Disclosure Number: IPCOM000095145D
Original Publication Date: 1965-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Mader, S: AUTHOR [+2]

Abstract

Amorphous ferromagnetic Co-Au alloys are realized which are stable to approximately 0.35 Tm, where Tm is the average melting point of the constituents. The system Co-Au has very limited equilibrium solubility and large size difference, -- 15%. The identification of the structure as amorphous is based on the appearance of highly diffuse diffraction rings and on the absence of discrete grains through observation by electron microscopy with a resolution down to 5A. Further indication of an amorphous alloy is the occurrence of relatively abrupt changes in the resistivity measured in situ in a narrow temperature range during gradual heating. After this, the film is found to be single-phase crystalline.

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Amorphous Ferromagnetic Alloys

Amorphous ferromagnetic Co-Au alloys are realized which are stable to approximately 0.35 Tm, where Tm is the average melting point of the constituents. The system Co-Au has very limited equilibrium solubility and large size difference, -- 15%. The identification of the structure as amorphous is based on the appearance of highly diffuse diffraction rings and on the absence of discrete grains through observation by electron microscopy with a resolution down to 5A. Further indication of an amorphous alloy is the occurrence of relatively abrupt changes in the resistivity measured in situ in a narrow temperature range during gradual heating. After this, the film is found to be single-phase crystalline.

An amorphous ferromagnetic Co-Au alloy is deposited on a substrate by simultaneous evaporation at 10- Torr. from two independent sources. The substrate consists of a sapphire slide covered by a collodion film and is maintained at liquid nitrogen temperature, i. e., about 80 degrees K. The thickness of exemplary films is in the range 500 to 800 angstroms.

Alloys in the composition range 30-60 atomic % Au have high residual resistivity which decreases slightly upon warming to room temperature, e. g., 20 degrees C. Films at room temperature after removal from the vacuum system show a typical amorphous-type structure with two broad diffraction halos and no resolvable crystallinity at high resolution, under examination by electron diffraction a...