Column Access of a Bubble Lattice: Column Translation and Lattice Translation

Abstract

The use of a regular array. or lattice, of magnetic bubbles for the storage of information requires two kinds of functions: the read-write functions involving the generation and discrimination of bubbles with different wall structures, and the access functions involving the insertion and removal of bubbles at selected locations in the lattice. In a column-accessed bubble lattice device, accessing is accomplished by first translating the lattice to position the desired column of bubbles in an input-output access channel and then translating this column along the channel to a detector area outside of the lattice while simultaneously introducing new bubbles from a generator area at the other end of the channel. An analysis of the influence of device design parameters on access rate indicates that the most important parameters are the column translation rate and lattice capacity. A device is described that was designed to study the translation of a lattice of bubbles and of a single column of bubbles within the lattice. Quasistatic operating margins and dynamic measurements of this test device indicate that the column-access configuration provides feasible means for the rapid access of bubbles from a lattice. Table 1 Bubble diameter and feature size required for a storage density of 105bits!mm 2 •

Micromagnetic Study of Domain Wall-Pinning Characteristics With Step-Like Thickness Change in Thin Film

“…Here, we present a novel pinning method of a 180 domain wall in a thin film with an in-plane anisotropy using the thickness variation along the wall. In a garnet film having a perpendicular anisotropy, the stable bubble positions can be created by the film thickness variation [1], which can be attributed to the demagnetizing field component along the film thickness direction originating from the change in the film thickness [2]. This technique has been applied to the stripe domain stabilization using etched grooves in the Bloch line memory [3].…”