2-D Analytical Modeling of the Magnetic Tunnel Junctions Including Multidomain Effects: Predictive Insights and Design Optimization

This article presents a comprehensive 2-D analytical model for magnetic tunnel junctions (MTJs), encompassing the multidomain effect. Utilizing Green's function approach, it derives closed-form expressions for in-plane and out-of-plane multidomain demagnetization fields. Integrating these expressions into the ferromagnetic energy state equation (demagnetization energy density <tex-math notation="LaTeX">$+$</tex-math> exchange energy density) accurately depicts domain textures. The analysis reveals an exponential decrease in domain density with increasing free layer thickness. At the same time, the trend reverses with the insulating layer (MgO) thickness, leading to denser domain patterns that adversely impact tunneling magnetoresistance (TMR). The predictive nature of the model enables the derivation of device design guidelines. Optimizing free and insulating layer thicknesses allows peak device performance. Furthermore, applying physics-based approximations yields a simplified model.