  Topological crystalline insulators are topological insulators whose surface
states are protected by the crystalline symmetry, instead of the time reversal
symmetry. Similar to the first generation of three-dimensional topological
insulators such as Bi2Se3 and Bi2Te3, topological crystalline insulators also
possess surface states with exotic electronic properties such as spin-momentum
locking and Dirac dispersion. Experimentally verified topological crystalline
insulators to date are SnTe, Pb1-xSnxSe, and Pb1-xSnxTe. Because topological
protection comes from the crystal symmetry, magnetic impurities or in-plane
magnetic fields are not expected to open a gap in the surface states in
topological crystalline insulators. Additionally, because they are cubic
structure instead of layered structure, branched structures or strong coupling
with other materials for large proximity effects are possible, which are
difficult with layered Bi2Se3 and Bi2Te3. Thus, additional fundamental
phenomena inaccessible in three-dimensional topological insulators can be
pursued. In this review, topological crystalline insulator SnTe nanostructures
will be discussed. For comparison, experimental results based on SnTe thin
films will be covered. Surface state properties of topological crystalline
insulators will be discussed briefly.
