  Noncollinear antiferromagnets have promising potential to replace
ferromagnets in the field of spintronics as high-density devices with ultrafast
operation. To take full advantage of noncollinear antiferromagnets in
spintronics applications, it is important to achieve efficient manipulation of
noncollinear antiferromagnetic spin. Here, using the anomalous Hall effect as
an electrical signal of the triangular magnetic configuration, spin-orbit
torque switching with no external magnetic field is demonstrated in
noncollinear antiferromagnetic antiperovskite manganese nitride Mn$_3$GaN at
room temperature. The pulse-width dependence and subsequent relaxation of Hall
signal behavior indicate that the spin-orbit torque plays a more important role
than the thermal contribution due to pulse injection. In addition, multistate
memristive switching with respect to pulse current density was observed. The
findings advance the effective control of noncollinear antiferromagnetic spin,
facilitating the use of such materials in antiferromagnetic spintronics and
neuromorphic computing applications.
