Micromagnetic Study of Edge-Damage Effects in Perpendicular CoFeB/MgO Magnetic Tunnel Junction

Micromagnetic simulation was used to investigate the effects of edge damage in a perpendicular magnetic tunnel junction (MTJ) on thermal stability factor (A) and spin transfer torque switching behavior at 300 K. A significant decrease in A was observed in smaller MTJs with severe anisotropy field (Hk)-degradation of the damaged region. It was found that Hk degradation has a crucial influence on reference layer magnetization, causing “back hopping.” The probability of back hopping is higher for AP to P switching and increases with increasing Hk degradation. This back hopping can be suppressed by using a more stable reference layer or reducing the edge damage. In addition, it was shown that if saturation magnetization (Ms) at edge-damaged region decreased, no back hopping was observed.