  We consider the effects of doping the S = 1/2 kagome lattice with static
impurities. We demonstrate that impurities lower the number of low-lying
singlet states, induce dimer-dimer correlations of considerable spatial extent,
and do not generate free spin degrees of freedom. Most importantly, they
experience a highly unconventional mutual repulsion as a direct consequence of
the strong spin frustration. These properties are illustrated by exact
diagonalization, and reproduced to semi-quantitative accuracy within a dimer
resonating-valence-bond description which affords access to longer length
scales. We calculate the local magnetization induced by doped impurities, and
consider its implications for nuclear magnetic resonance measurements on known
kagome systems.
