Modeling and Optimization of Multi-Level Magnetic Tunnel Junctions for Nanoelectronic Applications

This project investigates the design, fabrication, simulation, and characterization of multi-level magnetic tunnel junction (MTJ) devices, with the goal of optimizing their magnetic switching behavior for applications in memory and logic circuits. MTJ devices, incorporating both single and two-crossed ellipses (TCE) as the free layer, were fabricated and tested to examine how electrode geometry and device configuration affect multi-state stability.

Magnetoresistance and planar Hall effect (PHE) measurements were performed to characterize device behavior under varied field conditions, with magnetoresistance measurements revealing performance limitations in achieving stable multi-state configurations, while PHE measurements demonstrated more consistent responses.

To complement experimental work, a theoretical model was developed to simulate the magnetic switching behavior of MTJs. This model incorporates angle-dependent adjustments to demagnetization energy, validated against micromagnetic simulations using Mumax3. Despite initial limitations, the model successfully captures key aspects of the magnetic behavior, providing a foundation for further optimization.

The absence of intermediate metrology steps during fabrication limited early detection of defects, highlighting the need for routine checks with test structures in future work. Additionally, further simulations of PHE responses and switching currents would be beneficial, aligning with future efforts to implement current-driven switching in MTJ networks.

This work establishes a framework for the iterative optimization of MTJ devices and suggests improvements to fabrication and measurement practices, supporting future development of stable, multi-state MTJs for nanoelectronic applications.