  Spintronic devices based on domain wall (DW) motion through ferromagnetic
nanowire tracks have received great interest as components of neuromorphic
information processing systems. Previous proposals for spintronic artificial
neurons required external stimuli to perform the leaking functionality, one of
the three fundamental functions of a leaky integrate-and-fire (LIF) neuron. The
use of this external magnetic field or electrical current stimulus results in
either a decrease in energy efficiency or an increase in fabrication
complexity. In this work, we modify the shape of previously demonstrated
three-terminal magnetic tunnel junction neurons to perform the leaking
operation without any external stimuli. The trapezoidal structure causes
shape-based DW drift, thus intrinsically providing the leaking functionality
with no hardware cost. This LIF neuron therefore promises to advance the
development of spintronic neural network crossbar arrays.
