Micromagnetic Study of Probabilistic Switching Behavior in Sub 20 nm-CoFeB/MgO Magnetic Tunnel Junction

The fast probabilistic switching in the sub 20 nm CoFeB/MgO-Magnetic tunnel junction (MTJ) with stepped- and pillar structure were studied using micromagnetic simulation. It was observed that back-hopping phenomenon was occurred for AP to P switching in the pillar structure, while both P to AP and AP to P error-free switching were accomplished within 2 ns in the stepped structure. It was found that this back-hopping was triggered by the reference layer flipping, and driven by both the stray filed from the pinned layer and voltage control of magnetic anisotropy (VCMA) effects. Furthermore, it was found that this back-hopping can be reduced by increasing the interface anisotropy of the reference layer and decreasing VCMA effects at the CoFeB-reference/MgO-barrier interface.