Magnetization Process of Stadium-Shaped Magnetic Tunnel Junction Cells for Artificial Spin Ice

Artificial spin ice (ASI) consists of submicron-sized magnetic cells, which shows emergent behaviors of the magnetizations in the cells. To apply the magnetization dynamics of the ASI to spintronics devices, it is important to understand the magnetization process of the cells. In the ASI samples, stadium shaped (SS) cells have been widely used. However, its magnetization process has not been well understood yet. In this study, we investigated the magnetization process of the SS cells by magnetoresistance measurement in magnetic tunnel junctions as well as micromagnetic simulation. It was found that the SS cells showed magnetization switching at a low field, which was triggered by the annihilation of the magnetic vortex.