Method for determining the magnetic anisotropy field in the manufacture of magnetic domain devices

A method for making a plurality of magnetic devices, each of said devices comprising a layer of a magnetic material on a substrate, said method comprising depositing said layer on said substrate and ascertaining the magnetic anisotropy field of said layer, such ascertaining comprising

• (1) subjecting said layer to a magnetic field in a direction having a chosen azimuth and a preferred angle of elevation, and
• (2) inspecting a magnetic domain pattern produced in said layer upon essential removal of said field,
• said method being characterized in that said preferred angle of elevation has been determined essentially by
• (i) determining a functional relationship between a tentative angle of elevation and a magnetic field strength, said tentative angle of elevation being associated with a tentative direction whose azimuth is essentially said chosen azimuth, and said magnetic field strength being the strength of a magnetic test field which is in said tentative direction and which is the weakest field such that, upon essential removal of said magnetic test field, a preferred magnetic domain pattern is produced in said layer, said preferred magnetic domain pattern being equal or most nearly equal, as a function of said magnetic field strength, to an array of essentially circular magnetic domains, and
• (ii) selecting said preferred angle of elevation to be essentially equal to an angle of elevation corresponding to an essentially linear portion of said functional relationship, said essentially linear portion being adjacent to a peak of said functional relationship.