  We report on the experimental evidence of magnetic helicoidal dichroism,
observed in the interaction of an extreme ultraviolet vortex beam carrying
orbital angular momentum with a magnetic vortex. Numerical simulations based on
classical electromagnetic theory show that this dichroism is based on the
interference of light modes with different orbital angular momenta, which are
populated after the interaction between the light phase chirality and the
magnetic topology. This observation gives insight into the interplay between
orbital angular momentum and magnetism, and sets the framework for the
development of new analytical tools to investigate ultrafast magnetization
dynamics.
