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Amorphous Electrodeposited Transition Metal Alloys for Magnetic Bubble Device Applications

IP.com Disclosure Number: IPCOM000080599D
Original Publication Date: 1974-Jan-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Cargill, GS: AUTHOR [+5]

Abstract

Theoretical calculations indicate that, in order to support stable bubble domains suitable for device purposes, a material must have uniaxial anisotropy perpendicular to the plane of the film or platelet with an anisotropy field H(a) which is greater than 4piM(s), where M(s) is the saturation magnetization. See J. A. Cape et al, J. Appl. Phys. 42, 5732 (1971).

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Amorphous Electrodeposited Transition Metal Alloys for Magnetic Bubble Device Applications

Theoretical calculations indicate that, in order to support stable bubble domains suitable for device purposes, a material must have uniaxial anisotropy perpendicular to the plane of the film or platelet with an anisotropy field H(a) which is greater than 4piM(s), where M(s) is the saturation magnetization. See J.
A. Cape et al, J. Appl. Phys. 42, 5732 (1971).

Amorphous films are potentially attractive for bubble device applications because their properties are less sensitive than those of crystalline materials to structural defects, and because the compositions available with amorphous films are not restricted by compound stoichiometry. Techniques for producing, by electrodeposition, amorphous films of transition metal alloys which support bubble domains are here demonstrated by preparing amorphous Ni-Co-P alloy films, in which bubbles as well as stripe domain patterns are observed.

Methods for electrodepositing Ni-P and Co-P alloys were discovered by Brenner et al, and some of these alloys were found to be amorphous. See Brenner et al, J. Res. Natl. Bur. Std. 44, 109 (1950). The amorphous Ni-P alloys were thought not to be ferromagnetic at room temperature, but the Co-P alloys are strongly ferromagnetic. See G. S. Cargill, III et al, Amorphous Magnetism, H. G. Eopper and A. M. deGraff, eds., p. 313, 1972. What has been found is that some of the Co-P alloys have sufficient uniaxial anisotropy to support stripe domains, but alloys containing up to 14 wt. % p do not form bubble domains even in applied magnetic fields as large as 2.5kG.

In order to obtain materials capable of supporting stable bubble domains in easily accessible magnetic fields, methods for electroplating amorphous ternary alloys of Ni, Co and P have been developed. The addition of Ni reduces the saturation magnetization of the alloy, without removing the necessary perpendicular anisotropy. The exact origin of the anisotropy is not known. It is believed to be associated with some structural anisotropy parallel to the growth direction. Further, it is not necessary to prepare the films in the presence of a magnetic field.

Electroless deposited Co-P alloys containing between...