Spin–orbit torque based physical unclonable function
G. Finocchio, T. Moriyama, R. De Rose, G. Siracusano, M. Lanuzza, V. Puliafito, S. Chiappini, F. Crupi, Z. Zeng, T. Ono, M. Carpentieri
Abstract
This paper introduces the concept of spin–orbit-torque-magnetic random access memory (SOT-MRAM) based physical unclonable function (PUF). The secret of the PUF is stored into a random state of a matrix of perpendicular SOT-MRAMs. Here, we show experimentally and with micromagnetic simulations that this random state is driven by the intrinsic nonlinear dynamics of the free layer of the memory excited by the SOT. In detail, a large enough current drives the magnetization along an in-plane direction. Once the current is removed, the in-plane magnetic state becomes unstable evolving toward one of the two perpendicular stable configurations randomly. In addition, we propose a hybrid CMOS/spintronics model to simulate a PUF realized by an array of 16 × 16 SOT-MRAM cells and evaluate the electrical characteristics. Hardware authentication based on this PUF scheme has several characteristics, such as CMOS-compatibility, non-volatility (no power consumption in standby mode), reconfigurability (the secret can be reprogrammed), and scalability, which can move a step forward the design of spintronic devices for application in security.