  We calculate exact zero-temperature real space properties of a substitutional
magnetic impurity coupled to the edge of a zigzag silicene-like nanoribbon.
Using a Lanczos transformation [Phys. Rev. B 91, 085101 (2015)] and the density
matrix renormalization group method, we obtain a realistic description of
stanene and germanene that includes the bulk and the edges as boundary
one-dimensional helical metallic states. Our results for substitutional
impurities indicate that the development of a Kondo state and the structure of
the spin correlations between the impurity and the electron spins in the
metallic edge state depend considerably on the location of the impurity. More
specifically, our real space resolution allows us to conclude that there is a
sharp distinction between the impurity being located at a crest or a trough
site at the zigzag edge. We also observe, as expected, that the spin
correlations are anisotropic due to an emerging Dzyaloshinskii-Moriya
interaction with the conduction electrons, and that the edges scatter from the
impurity and "snake" or circle around it. Our estimates for the Kondo
temperature indicate that there is a very weak enhancement due to the presence
of spin-orbit coupling.
