Compact Modeling of a Magnetic Tunnel Junction Based on Spin Orbit Torque

High endurance, high speed, scalability, low voltage, and CMOS-compatibility are the ideal attributes of memories that any integrated circuit designer dreams about. Adding non-volatility to all these features makes the magnetic tunnel junctions (MTJs) an ultimate candidate to efficiently build a hybrid MTJ/CMOS technology. Two-terminal MTJs based on spin-transfer torque (STT) switching have been intensively investigated in literature with a variety of model proposals. Despite the attractive potential of the STT devices, the issue of the common writing/reading path decreases their reliability dramatically. A three-terminal MTJ based on the spin-orbit torque (SOT) approach represents a pioneering way to triumph over current two-terminal MTJs by separating the reading and the writing paths. In this paper, we introduce the first compact model, which describes the SOT-MTJ device based on recently fabricated samples. The model has been developed in Verilog-A language, implemented on Cadence Virtuoso platform and validated with Spectre simulator. For optimized simulation accuracy, many experimental parameters are included in this model. Simulations prove the capability of the model to be efficiently used to design hybrid MTJ/CMOS circuits. Innovative logic circuits based on the SOT-MTJ device, modeled in this paper, are already in progress.