  We measure transport through gold grain quantum dots fabricated using
electromigration, with magnetic impurities in the leads. A Kondo interaction is
observed between dot and leads, but the presence of magnetic impurities results
in a gate-dependent zero-bias conductance peak that is split due to an RKKY
interaction between the spin of the dot and the static spins of the impurities.
A magnetic field restores the single Kondo peak in the case of an
antiferromagnetic RKKY interaction. This system provides a new platform to
study Kondo and RKKY interactions in metals at the level of a single spin.
