A framework for simulating hybrid MTJ/CMOS circuits: Atoms to system approach

A simulation framework that can comprehend the impact of material changes at the device level to the system level design can be of great value, especially to evaluate the impact of emerging devices on various applications. To that effect, we have developed a SPICE-based hybrid MTJ/CMOS (magnetic tunnel junction) simulator, which can be used to explore new opportunities in large scale system design. In the proposed simulation framework, MTJ modeling is based on Landau-Lifshitz-Gilbert (LLG) equation, incorporating both spin-torque and external magnetic field(s). LLG along with heat diffusion equation, thermal variations, and electron transport are implemented using SPICE-in built voltage dependent current sources and capacitors. The proposed simulation framework is flexible since the device dimensions such as MgO thickness and area, are user defined parameters. Furthermore, we have benchmarked this model with experiments in terms of switching current density (J_C), switching time (T_SWITCH) and tunneling magneto-resistance (TMR). Finally, we used our framework to simulate STT-MRAMs and magnetic flip-flops (MFF).