Figure 3: The [001] surface states of SnTe.
From: Topological crystalline insulators in the SnTe material class
(a) band dispersion and (b) Fermi surface. Note that in between 
and 
two surface bands with opposite mirror eigenvalues cross the Fermi energy, in agreement with nM = −2. (c) a set of Fermi surfaces at different energies, exhibiting a Lifshitz transition.
