  SnTe topological crystalline insulator nanowires have been grown by molecular
beam epitaxy on graphene/SiC substrates. The nanowires have cubic rock-salt
structure, they grow along [001] crystallographic direction and have four
sidewalls consisting of {100} crystal planes known to host metallic surface
states with Dirac dispersion. Thorough high resolution transmission electron
microscopy investigations show that the nanowires grow on graphene in the van
der Walls epitaxy mode induced when the catalyzing Au nanoparticle mixes with
Sn delivered from SnTe flux, providing liquid Au-Sn alloy. The nanowires are
totally free from structural defects, but their {001} sidewalls are prone to
oxidation, which points out on necessity of depositing protective capping in
view of exploiting the magneto-electric transport phenomena involving charge
carriers occupying topologically protected states.
