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TT: Fachverband Tiefe Temperaturen

TT 40: Topological Insulators (jointly with HL, MA)

TT 40.5: Vortrag

Mittwoch, 16. März 2011, 17:45–18:00, HSZ 04

Topological insulators in ternary compounds with a honeycomb lattice — •Stanislav Chadov¹, Jürgen Kübler², and Claudia Felser¹ — ¹Institut für Anorganische und Analytische Chemie, Johannes Gutenberg Universtität, 55099 Mainz — ²Institut für Festkörperphysik, Technische Universität Darmstadt, 64289 Darmstadt

Based on electronic structure calculations we propose the certain extension to the class of the topological insulators which provide the convenient material base to realize the phenomenon of quantum spin Hall effect intensively studied nowadays. These new candidates (e. g. LiAuSe, KHgSb) are ternary semiconductors with a weakly coupled honeycomb layers (e. g. Au-Se, Hg-Sb) analogical to a weakly graphite sheets. It makes them very similar to graphene which is a single layer of graphite: their band structures exhibit the so-called linearly dispersive Dirac cone centered at the Fermi energy. However, in contrast to graphene with two Dirac cones at K and K′ points, these materials exhibit the surface states formed by only a single Dirac cone at the Γ point, allowing for the non-vanishing quantum spin Hall effect. The additional stuffing" elements (Li, K, etc.) extend the material multifunctionality, i. e. give more possibilities for tuning and coupling of their properties. In contrast to other topologically non-trivial systems, as e. g. recently proposed half-Heuslers, the honeycomb compounds possess the non-zero band gap in the bulk, i. e. provide the “natural” 3D topological materials.