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Cobalt Ferrite Films

IP.com Disclosure Number: IPCOM000085955D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bajorek, CH: AUTHOR [+2]

Abstract

To have high-storage densities on magnetic recording media, high coercivities on the order of 400 < H(c) < 1000 oe are required. Magnetic oxides (e.g., GammaFe(2)O(3) or Fe(3)O(4)) are preferred over metallic films because of environmental stability and mechanical wear properties.

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Cobalt Ferrite Films

To have high-storage densities on magnetic recording media, high coercivities on the order of 400 < H(c) < 1000 oe are required. Magnetic oxides (e.g., GammaFe(2)O(3) or Fe(3)O(4)) are preferred over metallic films because of environmental stability and mechanical wear properties.

Previously it has been suggested to sputter Fe in an oxygen atmosphere to form alpha Fe(2)O(3). Alternatively, the Fe is reactively evaporated or thermally oxidized. Next, the Fe is overcoated onto the alphaFe(2)O(3). Then annealing at 360 degrees C yields Fe(3)O(4) plus Fe' where Fe' < Fe. Then the Fe(3)O(4) plus Fe' is etched to remove the free iron from the Fe(3)O(4).

Here it is suggested that preferably instead of adding Fe to alphaFe(2)O(3) that Co should be overcoated onto the alphaFe(2)O(3), and next the resulting product is annealed at 350-400 degrees C yielding Co(x)Fe(3-x)O(4) + Co' where Co' < Co. Then the resultant product is etched to remove the Co' yielding Co(x)Fe(3-x)O(4) This provides very high coercivities compared with the previous process. It is believed that the composition of Co and Fe is such that x = 1/3(Co) and 3-x = 8/3(Fe).

Another process tried involved depositing Fe plus Co plus 0(2) to yield Fe(x)Co(y)O(3). Then Fe is overcoated onto the resulting material, to yield Fe(x),Co(y),O(4) + Fe'. Then the product is etched to remove the Fe'.

Still another process is in general to deposit Fe plus Co plus O(2) on the substrate to yield nonmagnet...