2014/12/31 by Emmanouil Frantzeskakis, E. Frantzeskakis, Nick de Jong +21
Materials Science · Physics and Astronomy · #Condensed matter physics #Electron #Electronic band structure #Electronic structure #Fermi level #Geometry #Graphene research and applications #Materials science #Physics #Quantum Mechanics and Non-Hermitian Physics #Quantum mechanics #Surface (topology) #Surface states #Topological Materials and Phenomena #Topological insulator #Topology (electrical circuits) #cond-mat.mtrl-sci
paper · pdf · doi:10.1038/srep16309
published as Scientific Reports 5, Article number: 16309 (2015) · 7 pages, 3 figures, includes Supplementary Information
openalex publication_date 2015/11/06 · arxiv created 2015/11/27 · arxiv updated 2015/11/30 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/05
In an ideal 3D topological insulator (TI), the bulk is insulating and the surface conducting due to the existence of metallic states that are localized on the surface; these are the topological surface states. Quaternary Bi-based compounds of Bi(2-x)Sb(x)Te(3-y)Se(y) with finely-tuned bulk stoichiometries are good candidates for realizing ideal 3D TI behavior due to their bulk insulating character. However, despite its insulating bulk in transport experiments, the surface region of Bi(2-x)Sb(x)Te(3-y)Se(y) crystals cleaved in ultrahigh vacuum also exhibits occupied states originating from the bulk conduction band. This is due to adsorbate-induced downward band-bending, a phenomenon known from other Bi-based 3D TIs. Here we show, using angle-resolved photoemission, how an EUV light beam of moderate flux can be used to exclude these topologically trivial states from the Fermi level of Bi1.46Sb0.54Te1.7Se1.3 single crystals, thereby re-establishing the purely topological character of the low lying electronic states of the system. We furthermore prove that this process is highly local in nature in this bulk-insulating TI, and are thus able to imprint structures in the spatial energy landscape at the surface. We illustrate this by 'writing' micron-sized letters in the Dirac point energy of the system.