  We examine binary mixtures of superparamagnetic colloidal particles confined
to a two-dimensional water-air interface both by real-space experiments and
Monte-Carlo computer simulations at high coupling strength. In the simulations,
the interaction is modelled as a pairwise dipole-dipole repulsion. While the
ratio of magnetic dipole moments is fixed, the interaction strength governed by
the external magnetic field and the relative composition is varied. Excellent
agreement between simulation and experiment is found for the partial pair
distribution functions including the fine structure of the neighbour shells at
high coupling. Furthermore local crystal nuclei in the melt are identified by
bond-orientational order parameters and their contribution to the pair
structure is discussed.
