  Current-induced spin torques provide efficient data writing approaches for
magnetic memories. Recently, the spin splitting torque (SST) was theoretically
predicted (R. Gonz\'alez-Hern\'andez et al. Phys. Rev. Lett. 126, 127701
(2021)), which combines advantages of conventional spin transfer torque (STT)
and spin-orbit torque (SOT) as well as enables controllable spin polarization.
Here we provide the experimental evidence of SST in collinear antiferromagnet
RuO2 films. The spin current direction is found to be correlated to the crystal
orientation of RuO2 and the spin polarization direction is dependent on
(parallel to) the N\'eel vector. These features are quite characteristic for
the predicted SST. Our finding not only present a new member for the spin
torques besides traditional STT and SOT, but also proposes a promising spin
source RuO2 for spintronics.
