The present work
discusses the proposal of a spintronic neuromorphic system with spin orbit
torque driven domain wall motion-based neuron and synapse. We propose a
voltage-controlled magnetic anisotropy domain wall motion based magnetic tunnel
junction neuron. We investigate how the electric field at the gate (pinning
site), generated by the voltage signals from pre-neurons, modulates the domain
wall motion, which reflects in the non-linear switching behaviour of neuron
magnetization. For the implementation of synaptic weights, we propose
3-terminal MTJ with stochastic domain wall motion in the free layer. We
incorporate intrinsic pinning effects by creating triangular notches on the
sides of the free layer. The pinning of domain wall and intrinsic thermal noise
of device lead to the stochastic behaviour of domain wall motion. The control
of this stochasticity
by the spin orbit torque is shown to realize the potentiation and depression of
the synaptic weight. The micromagnetics and spin transport studies in synapse
and neuron are carried out by developing a coupled micromagnetic
Non-Equilibrium Green’s Function (<i>MuMag-NEGF</i>) model. The minimization of
the writing current pulse width by leveraging the thermal noise and demagnetization
energy is also presented. Finally, we
discuss the implementation of digit recognition by the proposed system using a spike
time dependent algorithm.
Domain wall-magnetic tunnel junction spin–orbit torque devices and circuits for in-memory computing
