Investigating magnetic immunity in state-of-the-art MRAM

Spin-transfer torque magnetic random access memory (STT-MRAM) and spin-orbit torque MRAM (SOT-MRAM) are emerging non-volatile memory technologies that promise high density, low power consumption, and fast access times. However, data loss or erroneous operation due to accidental or deliberate exposure to magnetic fields can reduce the reliability and lifetime of the memory. Magnetic immunity, which refers to the ability of a memory device to maintain its magnetic state in the presence of external magnetic fields, is therefore a critical aspect of MRAM design and operation.

In this PhD, the student will investigate magnetic immunity in MRAM, understand the physical parameters determining the behavior under various magnetic field disturbances and propose strategies to enhance the magnetic immunity. Following an initial phase of exploration, the student is encouraged to focus primarily on one technology, either STT or SOT-MRAM.

The thesis work will involve following tasks:

1. Literature review: Conduct a thorough review of the existing literature on magnetic immunity in MRAM, including the sources of magnetic disturbances and the existing solutions to enhance magnetic immunity.
2. Design experiments on existing state-of-the-art STT-MRAM and SOT-MRAM devices to study impact of external magnetic fields on switching.
3. Modeling and simulation: Use micromagnetic simulation tools such as OOMMF/Mumax to model and simulate the behavior of MRAM cells under various magnetic field disturbances. Develop understanding of what and how cell operation can be impacted by external fields.
4. Design optimization: Based on the simulation and experimental results, propose and optimize strategies to enhance the magnetic immunity of MRAM cells, such as changing the cell shape or materials, adjusting the cell dimensions, and adding shielding layers.