Selection rules for light-induced magnetization of a crystal with threefold symmetry: the case of antiferromagnetic NiO

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 micromultidomain structure, which excellently agreed with the theoretical prediction.