We have studied a Co/Cu/Co trilayer circular ring by using a current-in-plane giant magnetoresistance (GMR) method. When the applied field angle is shifted from the current probes, four distinctive magnetization reversal patterns are obtained depending on the vortex chirality configurations in the top and bottom rings. During the repeated GMR measurements, two GMR patterns are preferentially appeared and it turns out that the same chirality is favorable between the top and the bottom rings. Micromagnetic simulation reproduces the experimental data by taking into account the domain wall shift at the onion states.
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