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SKM-SYTI: SKM-Symposium Topological Insulators

SKM-SYTI 1: Topological Insulators

SKM-SYTI 1.5: Hauptvortrag

Mittwoch, 16. März 2011, 12:30–13:00, TRE Ma

Tunable multifunctional topological insulators in ternary Heusler and related compounds — •Claudia Felser¹, Stanislav Chadov¹, Lukas Müchler¹, Jürgen Kübler², Shou Cheng Zhang³, Xiaoliang Qi³, and Hai-Jun Zhang³ — ¹University Mainz — ²TU Darmstadt — ³Stanford University

Recently the quantum spin Hall effect was theoretically predicted and experimentally realized in quantum wells based on the binary semiconductor HgTe. The quantum spin Hall state and topological insulators are new states of quantum matter interesting for both fundamental condensed-matter physics and material science. Many Heusler compounds with C1b structure are ternary semiconductors that are structurally and electronically related to the binary semiconductors. The diversity of Heusler materials opens wide possibilities for tuning the bandgap and setting the desired band inversion by choosing compounds with appropriate hybridization strength (by the lattice parameter) and magnitude of spinorbit coupling (by the atomic charge). Based on first-principle calculations we demonstrate that around 50 Heusler compounds show band inversion similar to that of HgTe. The topological state in these zero-gap semiconductors can be created by applying strain or by designing an appropriate quantumwell structure, similar to the case of HgTe. Many of these ternary zero-gap semiconductors (LnAuPb, LnPdBi, LnPtSb and LnPtBi) contain the rare-earth element Ln, which can realize additional properties ranging from superconductivity (for example LaPtBi) to magnetism (for example GdPtBi) and heavy fermion behaviour (for example YbPtBi).