Purely Electrical Controllable Spin-Orbit Torque-Based Reconfigurable Physically Unclonable Functions

In the field of information hardware security, random variations obtained during device manufacturing process play a key role in generating unique and unclonable security keys. Existing physical unclonable functions (PUFs) utilizing these static randomnesses usually exhibit static challenge-response pairs, which cannot be refreshed and limit their application prospects. Here, it is demonstrated that purely electrical controllable spin-orbit torque (SOT)-based reconfigurable PUFs (rPUFs) can be realized in Pt/IrMn/Co/Ru/CoPt heterojunctions. By applying current pulses along two orthogonal directions, both the exchange bias between IrMn and Co and the SOT switching polarity (clockwise or counterclockwise) of perpendicularly magnetized CoPt can be reversibly controlled, which enables the realization of four rPUF states within a single device. By taking advantages of the sample growth and micro-nanofabrication induced variations in the critical switching current density of SOT-driven magnetization switching, the rPUF device with relatively good uniqueness and low bit error rate is achieved. Our work provides an approach to information hardware security and broadens the application of spintronics.