Current-induced vortex-vortex switching in a nanopillar comprising two Co nano-rings

TL;DR

This study demonstrates current-induced vortex state switching in a Co nano-ring nanopillar, highlighting the roles of Oersted field and spin-transfer torque in magnetic transitions, with potential applications in spintronic devices.

Contribution

It introduces a method to control vortex states in Co nano-rings using dc current, emphasizing the dominance of Oersted field and the interplay with spin-transfer torque.

Findings

Current can induce vortex state switching in Co nano-rings.

Abrupt vortex transitions detected via giant magnetoresistance.

Oersted field is the dominant factor in magnetic transitions.

Abstract

We fabricated a current-perpendicular-to-plane pseudo-spin-valve nanopillar comprising a thick and a thin Co rings with deep submicron lateral sizes. The dc current can effectively induce the flux-closure vortex states in the rings with desired chiralities. Abrupt transitions between the vortex states are also realized by the dc current and detected with the giant magnetoresistance effect. Both Oersted field and spin-transfer torque are found important to the magnetic transitions, but the former is dominant. They can be designed to cooperate with each other in the vortex-to-vortex transitions by carefully setting the chirality of the vortex state in the thick Co ring.