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MM: Fachverband Metall- und Materialphysik
MM 16: Computational Materials Modelling - Novel Materials
MM 16.2: Vortrag
Montag, 20. März 2017, 16:00–16:15, IFW B
Possible Gating on the Surface of a Weak Topological Insulator: Bi14Rh3I9 — •Madhav Prasad Ghimire1 and Manuel Richter1,2 — 1Leibniz Institute for Solid State and Materials Research, IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany — 2Dresden Center for Computational Materials Science, DCMS, TU Dresden,D-01069 Dresden, Germany
Recently synthesized Bi14Rh3I9 was predicted to be a weak topological insulator. Scanning tunneling microscopy confirms this with a signatures of one-dimensional conducting states in the band gap at step edges of [(Bi4Rh)3I]2+ (2DTI) surface layers. However, the surface-layer gap is found 0.25 eV below the Fermi level (EF). Transport experiments are expected to be biased by intrinsic n-doping at the surface. Using density functional theory slab calculations we resolve this issue to shift EF into the surface layer gap without losing its topological properties. We perform chemical modification on the surface of Bi14Rh3I9: sparse layer of Iodine atoms is added onto the 2DTI surface. Investigation shows that deposition of one I atom per surface unit cell onto 2DTI surface opens a surface gap of 0.1 eV at EF, if simultaneously one I atom is removed from the dorsal spacer layer. The same effect with reduced gap size (0.08 eV) is observed for adding/removing I atoms in two fold higher concentration. Comparing our results with the experiment [ACS Nano, 2016] we predict that Fermi level can be shifted to the surface gap by deposition of I atoms onto the 2DTI surface in an appropriate range of concentration.