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

Artificial spin ice (ASI) consisted of submicron-sized magnetic cells, which showed emergent behavior 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 were widely used, however, whose magnetization process has not been well understood. 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.