Coercive force of electrodeposited NiFe on top of conductors for SLM bubble device applications

Reduction of the bubble size in bubble devices made evident that the permalloy used in the structure has to comply with very strict specifications of coereivity and remanence. This paper reports on a study aimed at minimizing the Hc of permalloy electroplated on top of thick gold conductor, such as is used in the SLM, conductor first, devices. The coercive force of electroplated permalloy was studied as a function of the type of the underlying metal conductor, its thickness, and its surface characteristics as determined by the type and rate of deposition. Also studied were the correlation between Hc and the electroplated permalloy thickness, and the effect of annealing on the coercive force. It was found that reproducibly the best magnetic properties of permalloy are obtained when a thin layer of permalloy is evaporated on the gold conductor prior to electrodeposition of the permalloy structure.