title: Spin-transfer torque magnetic memory as a stochastic memristive synapse for neuromorphic systems.
abstract: Spin-transfer torque magnetic memory (STT-MRAM) is currently under intense academic and industrial development, since it features non-volatility, high write and read speed and high endurance. In this work, we show that when used in a non-conventional regime, it can additionally act as a stochastic memristive device, appropriate to implement a "synaptic" function. We introduce basic concepts relating to spin-transfer torque magnetic tunnel junction (STT-MTJ, the STT-MRAM cell) behavior and its possible use to implement learning-capable synapses. Three programming regimes (low, intermediate and high current) are identified and compared. System-level simulations on a task of vehicle counting highlight the potential of the technology for learning systems. Monte Carlo simulations show its robustness to device variations. The simulations also allow comparing system operation when the different programming regimes of STT-MTJs are used. In comparison to the high and low current regimes, the intermediate current regime allows minimization of energy consumption, while retaining a high robustness to device variations. These results open the way for unexplored applications of STT-MTJs in robust, low power, cognitive-type systems.
authors.forename: Adrien F
authors.initials: AF
authors.lastname: Vincent
authors.forename: Jerome
authors.initials: J
authors.lastname: Larroque
authors.forename: Nicolas
authors.initials: N
authors.lastname: Locatelli
authors.forename: Nesrine
authors.initials: N
authors.lastname: Ben Romdhane
authors.forename: Olivier
authors.initials: O
authors.lastname: Bichler
authors.forename: Christian
authors.initials: C
authors.lastname: Gamrat
authors.forename: Wei Sheng
authors.initials: WS
authors.lastname: Zhao
authors.forename: Jacques-Olivier
authors.initials: JO
authors.lastname: Klein
authors.forename: Sylvie
authors.initials: S
authors.lastname: Galdin-Retailleau
authors.forename: Damien
authors.initials: D
authors.lastname: Querlioz
mesh_terms: D006801:Humans; D008280:Magnetics; D009010:Monte Carlo Method; D036103:Nanotechnology; D016571:Neural Networks, Computer; D009474:Neurons / Q000378:metabolism / Q000502:physiology; D013569:Synapses / Q000502:physiology*; D019415:Torque