Optical Verification of Physically Unclonable Function Devices Based on Spin-Orbit Torque Switching

Abstract

Physically unclonable functions (PUFs) are used for various applications such as anticounterfeiting, authentication, and secret key generation. They are generally evaluated through electrical measurements, requiring much time and effort due to the many electrical connections required. This study proposes an optical verification of spin-orbit torque (SOT) devices for PUF design. SOT devices have gained much attention because they resist degradation and thermal changes and can generate secret keys with high reproducibility. A simple optical method based on the magneto-optical Kerr effect is introduced to verify the authenticity of the proposed SOT PUF device. Furthermore, this study assesses the feasibility of using a W/CoFeB/MgO/Ta structure as a PUF. The 24-bit device shows a reliability of 97.8 ± 1.03%, making it a promising candidate for use as a spintronics-based PUFs.