  This work proposes a novel logic device (SkyLogic) based on skyrmions, which
are magnetic vortex-like structures that have low depinning current density and
are robust to defects. A charge current sent through a polarizer ferromagnet
(P-FM) nucleates a skyrmion at the input end of an intra-gate FM interconnect
with perpendicular magnetic anisotropy (PMA-FM). The output end of the PMA--FM
forms the free layer of an MTJ stack. A spin Hall metal (SHM) is placed beneath
the PMA-FM. The skyrmion is propagated to the output end of the PMA-FM by
passing a charge current through the SHM. The resistance of the MTJ stack is
low (high) when a skyrmion is present (absent) in the free layer, thereby
realizing an inverter. A framework is developed to analyze the performance of
the SkyLogic device. A circuit-level technique is developed that counters the
transverse displacement of skyrmion in the PMA-FM and allows use of high
current densities for fast propagation. The design space exploration of the
PMA-FM material parameters is performed to obtain an optimal design point. At
the optimal point, we obtain an inverter delay of 434 ps with a switching
energy of 7.1 fJ.
