Spintronic Device-Circuit Modeling
SPICE-compatible modeling of MTJs with second-order anisotropy
Project Overview
This project developed a SPICE-based compact model for monodomain magnetic tunnel junctions (MTJs) by incorporating second-order magnetocrystalline anisotropy contributions into the Landau-Lifshitz-Gilbert (LLG) framework. The model enables accurate simulation of magnetization dynamics in perpendicular (PMA) and in-plane (IMA) magnets, critical for reliable MRAM design.
Key Features
🧲 Second-Order Anisotropy: Captures effects ignored in conventional first-order-only models
⚡ SPICE-Compatible: Reformulated stochastic LLG equations into circuit-equivalent form for integration in circuit simulators
📐 Critical Parameter Extraction: Evaluated switching thresholds, critical spin current, and external field requirements
🔄 Noise Inclusion: Stochastic dynamics modeled for realistic reliability studies
Research Contributions
Built a physics-based SPICE-compatible model of a monodomain magnet including higher-order anisotropy
Modeling_Second_Order_Anisotrop…Demonstrated significant increases in critical field and spin current when second-order anisotropy is comparable to first-order
Validated model accuracy by benchmarking against theoretical values and prior experimental reports
Highlighted the importance of anisotropy effects in low-barrier magnets for unconventional computing (e.g., probabilistic spin logic)
Technical Achievements
Showed up to 2–3× increases in required critical field/current with rising second-order anisotropy
Modeled both 40 kBT and 60 kBT PMA magnets, reproducing experimental trends
Produced a modular, extendable SPICE framework adaptable for hybrid MTJ/CMOS circuit simulations
Applications
MRAM reliability analysis under scaling and anisotropy variation
Hybrid MTJ/CMOS design flows for memory and logic applications
Spintronic neuromorphic and probabilistic computing, leveraging low-barrier magnets
Impact and Recognition
This work advanced device–circuit co-design in spintronics by enabling system-level simulation of MTJs that account for second-order anisotropy effects. Results were presented at the IEEE ICECE 2022 and demonstrated the importance of higher-order anisotropy in next-generation magnetic memory and computing devices
