  We propose Raman-induced collinear difference-frequency generation (DFG) as a
method to manipulate dynamical magnetization. When a fundamental beam
propagates along a threefold rotational axis, this coherent second-order
optical process is permitted by angular momentum conservation through the
rotational analogue of the Umklapp process. As a demonstration, we
experimentally obtained polarization properties of collinear magnetic DFG along
a [111] axis of a single crystal of antiferromagnetic NiO with micro
multidomain structure, which excellently agreed with the theoretical
prediction.
