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TT: Fachverband Tiefe Temperaturen

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

TT 40.6: Vortrag

Mittwoch, 16. März 2011, 18:00–18:15, HSZ 04

Thallium-based topological insulators from first principles — •Gustav Bihlmayer¹, Sergey V. Eremeev², Stefan Blügel¹, and Eugene V. Chulkov³ — ¹Peter Grünberg Institut (PGI-1) and Institute for Advanced Simulation (IAS-1), Forschungszentrum Jülich and JARA, Jülich, Germany — ²Institute of Strength Physics and Materials Science, Tomsk, Russia — ³Donostia International Physics Center (DIPC), San Sebastián, Spain

Currently, there is a substantial interest in topological insulators, which show protected edge-states carrying dissipationless spin currents. Among the new classes of these materials the Tl-based compounds TlAB₂ (A=Bi,Sb; B=Se,Te) have attracted considerable interest both on the experimental and theoretical side. We present density functional theory calculations of the bulk materials and their (111) surfaces, displaying protected Dirac-cone shaped surface states together with "trivial" surface states. In contrast to layered materials like Bi₂Te₃, these compounds are of more three-dimensional character. From the bulk calculations we observe a strong sensitivity of the topological properties on the structural details, that have to be described very accurately. In the surface calculations deeply penetrating Dirac-cone states are observed, calling for careful convergence of the calculations with respect to the film thickness. Similar materials, e.g. the sulfides and InAB₂ compounds will be discussed for comparison.