Device Implications of the Theory of Cylindrical Magnetic Domains*

Abstract

This paper applies the theory of cylindrical magnetic domains <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> to cylindrical domain devices. The stability conditions are examined as bounds to the region of possible device operation and it is found that the plate thickness, h = 4l, and the domain diameter, d = 8l, where l is the ratio of the wall energy per unit area to 4π times the saturation magnetization squared, are preferred values. When the effects of wall coercivity and mobility are examined, it is found that the preferred plate thickness and domain diameter are even more strongly preferred, that the wall motion coercivity should be less than one percent of 4π times the saturation magnetization, and that a domain coercivity and mobility may be defined. Consideration of the Néel temperature and the desired absolute domain size in addition to the static stability conditions shows that domain materials having some antiferromagnetic character and induced uniaxial anisotropy are preferred. Where appropriate, domain methods for measuring material parameters are described.