  The role of spin fluctuations near magnetic phase transitions is crucial for
generating various exotic phenomena, including anomalies in the extraordinary
Hall effect, excess spin-current generation through the spin-Hall effect (SHE),
and enhanced spin-pumping, amongst others. In this study, we experimentally
investigate the temperature dependence of spin-orbit torques (SOTs) generated
by Mn3Ni0.35Cu0.65N (MNCN), a member of the noncollinear antiferromagnetic
family that exhibits unconventional magnetotransport properties. Our work
uncovers a strong and nontrivial temperature dependence of SOTs, peaking near
the N\'eel temperature of MNCN, which cannot be explained by conventional
intrinsic and extrinsic scattering mechanisms of the SHE. Notably, we measure a
maximum SOT efficiency of 30%, which is substantially larger than that of
commonly studied nonmagnetic materials such as Pt. Theoretical calculations
confirm a negligible SHE and a strong orbital Hall effect that can explain the
observed SOTs. We propose a previously unidentified mechanism wherein
fluctuating antiferromagnetic moments trigger the generation of substantial
orbital currents near the N\'eel temperature due to the emergence of scalar
spin chirality. Our findings present an approach for enhancing SOTs, which
holds promise for magnetic memory applications by leveraging antiferromagnetic
spin fluctuations to amplify both orbital and spin currents.
