  Non-collinear antiferromagnets exhibits richer magneto-transport properties
due to the topologically nontrivial spin structure they possess compared to
conventional nonmagnetic materials, which allows us to manipulate the
charge-spin conversion more freely by taking advantage of the chirality. In
this work, we explore the unconventional spin orbit torque of L1$_2$-ordered
Mn$_3$Pt with a triangular spin structure. We observed an unconventional spin
orbit torque along the $\mathbf{x}$-direction for the (001)-oriented L1$_2$
Mn$_3$Pt, and found that it has a unique sign reversal behavior relative to the
crystalline orientation. This generation of unconventional spin orbit torque
for L1$_2$-ordered Mn$_3$Pt can be interpreted as stemming from the magnetic
spin Hall effect. This report help clarify the correlation between the
topologically nontrivial spin structure and charge-spin conversion in
non-collinear antiferromagnets.
