Interisland spacing and angle effects on magnetic reversal in permalloy arrays

The switching characteristics of submicron permalloy elements were systematically studied as a function of interisland spacing. The result was an increase of the switching field with reduction in spacing, with a maximum value for near zero spacing. However, in overlapped segments, all elements switched simultaneously at lower fields than the maximum at zero spacing. The switching field depends on the number of connected segments as described by the Jacobs-Bean model, whereas the switching of the separated islands is governed mainly by the field emanating from the nearest-neighbor magnetic poles. The reversal behavior of the branched contiguous array was also studied. The angle between the branch axis and the easy axis played a critical role in establishing the switching field. The reversal field of the branched segment reached a minimum at 45° and a maximum at 90°. A coherent rotation model, which includes the effect of the array geometry, appears to explain the trends.