Modeling of Magnetic Tunnel Junction Switching by Voltage-Controlled Exchange Coupling

Recently, experiments have demonstrated that voltage-controlled exchange coupling (VCEC) can realize bipolar switching with ultra-low switching current density in the MTJ with a synthetic antiferromagnetic free layer. In this Letter, we develop a compact model for the abovementioned VCEC-MTJ. We demonstrate that VCEC can realize bipolar nanosecond level switching with ultra-low current. We analyze the energy profile of VCEC-MTJ under different bias voltages, showing that VCEC adds a strong linear term to the energy profile and significantly reduces the energy barrier height. We also analyze the relationship between switching time and voltage and find that the switching induced by VCEC can be divided into the thermally activated and precessional regimes. Moreover, we examine the effect of spin-transfer torque and voltage-controlled magnetic anisotropy and demonstrate that the device can be further optimized. Our findings illustrate that VCEC is a practical approach to realize low-power ultra-fast bipolar voltage-controlled switching of MTJ, which could overcome the major problems in the future development of state-of-the-art spintronic devices.