Bubble domain field access device modeling part I: The magnetization problem

A model of magnetic bubble propagation patterns using surface charge embedded in a minimum domain configuration

“…The low field magr;etization curve from [ l ] has been scaled to the bar size used for the other curves. The simple surface charge model gives nearly the same magnetization as the model of [2] , and calculations for other domain wall configurations (not shown here) produce a narrow clustering of magnetization values about the curve from [2]. Thus it appears that the simple surface charge model is essentially equivalent to the linear twodimensional continuum model when used to predict average magnetization.…”

“…1 together with the experimental points (two bar samples) and the magnetization curves predicted by several models. The graph compares results from the surface charge model and a corrected version (to be discussed later) with the twodimensional continuum models of [l] and [2] . The low field magr;etization curve from [ l ] has been scaled to the bar size used for the other curves.…”

“…When the charge is allowed tQ spread onto the film surfaces in the strip configurations of Fig. 2, the energy of the three charged surfaces in a "C" or '61" arrangement has the form E=allp: a22P2 +a33P; a l 2 P l P 2 ' a l 3 P l P 3 ' a23P2P3, 2 ( 1 2) where by symmetry, p3 = p z , a33 = a22, and a13 = a12. Charge spreading does not alter the total quantity of charge, which is given by…”

“…For a bar shape, the two models have virtually the same average magnetization and field contours. The dependence of average magnetization on the granularity of the finite element treatment noted in [2] is very slight in the surface charge model, provided that the length and position of the charged surfaces allow a reasonably complete coverage of both the positively and negatively charged regions of the polygon.…”

“…An alternative is to study only the propagation field produced by the Permalloy patterns, and this is the choice that is made here. Consequently, the scope of this work is similar to [2] . It is appropriate now to consider how a limited model which treats only the magnetization problem can be of value in the device design process.…”