A High-Accuracy STT-MTJ SPICE Model Based on Variable Parameters

Fokker–Planck equation (FPE)-based spin-transfer torque magnetic tunnel junction (STT-MTJ) SPICE model demonstrates advantages in terms of time efficiency and the description of magnetic moment dynamics. However, achieving high-accuracy simulation results remains a challenge. In this article, we present a variable parameter model to compensate for the physical effects that are not captured by the FPE. By defining relaxation time and thermal stability factor as functions of effective input current, the model achieves strong agreement with multiple sets of experimental data and reduces the error rate to below 2%. Furthermore, this approach preserves the model’s ability to describe both the dynamic and stochastic characteristics of the STT-MTJ, ensuring its suitability for a broad range of practical applications in circuit simulation. The model is implemented in Verilog-A language, and hybrid circuit simulations prove that it has the ability to work with other standard devices in electronic design automation (EDA) tools, just like HSPICE.