Phase-change-assisted spin-transfer torque switching in perpendicular magnetic tunnel junctions

Magnetic anisotropy modulation is an effective method to simultaneously reduce the switching current and extend the data retention of magnetic tunnel junction (MTJ), which is promising to be used in the next-generation spin transfer torque (STT) magnetic random-access memory. However, to meet the requirements of high storage life and harsh environments, the improved perpendicular magnetic anisotropy of MTJ makes the conventional modulation methods suffer from high breakdown risk owing to the relatively low efficiency. In this paper, a method of phase-change controlled magnetic anisotropy (PCMA) is introduced to a physical model of VO2/CoFeB/MgO/CoFeB perpendicular MTJ with superior modulation capability proved by systematical simulation. The time sequence of phase change pulse and STT pulse is studied, proving that there exists a specific interval to achieve both rapid and low-power switching. With the joint effect of PCMA and STT, low-energy (68.2 fJ), low-error-rate (0.08), and fast (2 ns) write operation can be achieved in the MTJ accompanied by a high thermal stability factor (78). The results demonstrate that the PCMA-STT switching strategy is most suitable for MTJ with large perpendicular magnetic anisotropy, paving a promising way to replace NOR flash memories.