A novel topological insulator with orthorhombic crystal structure is
demonstrated. It is characterized by quasi one-dimensional, conducting atomic
chains instead of the layered, two-dimensional sheets known from the
established Bi2(Se,Te)3 system. The Sb-doped Bi2Se3 nanowires are grown in a
TiO2-catalyzed process by chemical vapor deposition. The binary Bi2Se3 is
transformed from rhombohedral to orthorhombic by substituting Sb on ∼38% of
the Bi sites. Pure Sb2Se3 is a topologically trivial band insulator with an
orthorhombic crystal structure at ambient conditions, and it is known to
transform into a topological insulator at high pressure. Angle-resolved
photoemission spectroscopy shows a topological surface state, while Sb doping
also tunes the Fermi level to reside in the bandgap
