Assessing Magnetic Attack on Commercial 40nm pMTJ STT-MRAM

In this paper, we experimentally evaluate the data integrity of commercial Spin-Transfer-Torque (STT) based Magnetic Random Access Memory (MRAM) under external magnetic fields. Our findings reveal that the standby immunity field for the tested device is around 180 mT, beyond which both read and write operations are significantly affected. Post-exposure retention analysis indicates that over $50 \%$ of bits become noisy after field exposure, though this can be corrected with an overwrite operation. We provide a physical explanation for the origin of these noisy bits. Our results have significant implications for the data integrity of STT-MRAM under magnetic field-based external attacks.