Bi-stable and tri-stable Magnetic domain reconfigurations of a small permalloy pattern using current pulses

Realization of pulsed-current selectable domain configurations of small permalloy islands is reported. In the islands with 65-100 nm thickness and micron-sized lateral dimensions, the magnetic domain pattern can be uniquely set into either a four or seven closure domain configuration by applying either a positive or negative 10 ns current pulse at the density of 10⁷ A/cm². The transition is completely reversible. This phenomenon appears to belong to a family of current-induced magnetization reordering, whose main mechanism appears to be domain wall motion due to s-d exchange force directed along the electron flow, and partially influenced by the Amperian field produced at the contact regions. This paper presents two cases, namely, bi-stable and tri-stable configurations, and discusses the mechanism as well as power requirements in using this approach for memory device applications.