  We theoretically investigate how the orbital angular momentum of light can
affect a chiral magnetic order. Here, we consider a metallic chiral helimagnet,
which is under stationary radiation of a resonant optical vortex beam. We
propose a novel interaction between local spins considering microscopic
interactions between an optical vortex and electrons. This vortex-induced
interaction modulates the chiral magnetic order in an entirely different way
than an external magnetic field does. Our spin modulation technique may pave a
route to create a unique topological or chiral structure for future
opto-spintronics devices.
