Multilayer magnetic film with low magnetostriction effect - consists of alternating layers of iron, cobalt alloy and iron based alloy with high magnetic saturation properties

摘要

The multiple layer ferromagnetic film, which shows a high magnetic induction saturation level Bs and low magnetostriction lambdas contains alternating thin layers of a CoFe alloy (5a-5z), with 7-98 at.% Fe, and another ferromagnetic material. The second layers (6a-6z) consist at least partly of an alloy of Fe with a metalloid which has a saturation level Bs of at least 1.5 T and in which the metalloid (ME) is at least one of the following elements: B, Al, Ga, Si, Ge. Also claimed is an Fe-content of the first layer of max. 14 at.%, pref. 8-13 at.%. The second layers have pref. an ME-content of 1-70 at.% while still ferromagnetic. The ranges of content of the different elements are as follows: B 5-25 at.%, Al 1-20 at.%, Ga 1-8 at.%, Si 2-25 at.% and Ge 6-15 at.%. The thickness of the first layers (d1) is pref. 0.5-100 nm, especially 10 nm. The second layer is pref. thicker than the adjacent first layers, pref. d2 is between 10-30 times the value of d1. Also claimed is the use of the multilayer system in the mfr. of magnetic pick-up/writing heads or as ferromagnetic underlyaer of a magnetisable storage medium. USE/ADVANTAGE - The multiple layer system allows the properties to be adjusted to preferred values. Especially low magnetostriction, i.e. less than 10 power (-6), can be combined with high Bs values and high permeability, e.g. more than 1000, as well as a very low coercive field strength Hc. The layers can be deposited by sputtering or electroplating. Both types of layers can contain up to 5 at.% of other elements or impurities.