Conductor and transfer-gate performance of single-mask field-current access magnetic-bubble devices

Abstract

A highly sensitive magnetic bubble detector in an essentially singlemask overlay ABSTRACT Bubble propagation has been investigated in conductor structures on 5 /.lm-bubble (Y, Sm, Lu, Ca)3(Fe, Ge)5012' The conductors consist either entirely of permalloy or of a sandwich of permalloy on gold. A static in-plane field is used for unidirectional bubble propagation.The dependence of bubble motion on current amplitude and inplane field magnitude has been measured at low and high frequencies.The bubble motion was observed to consist of a first slow step where the current acts against the in-plane field, and a second quick step where both act together. Attainable frequencies increase with increasing in-plane field and current intensities up to a maximum of 1.1 MHz. The sandwich conductor has a 12% operating margin at 830 kHz frequency and 30 mA current. It performs better than the ali-permalloy conductor at the same overall spacing of the permalloy to the epifilm.An improved transfer gate from current to field-access has an 18% margin, from field to current-access 16%, at 100 kHz. The overlap with the conductor margins is 7% at in-plane fields from 30 Oe. The gates can be combined to obtain a field-current swap gate.