Topological Surface States and Dirac Point Tuning in Ternary Topological Insulators
Using angle-resolved photoemission spectroscopy, we report electronic structure for representative members of ternary topological insulators. We show that several members of this family, such as Bi2Se2Te, Bi2Te2Se, and GeBi2Te4, exhibit a singly degenerate Dirac-like surface state, while Bi2Se2S is a fully gapped insulator with no measurable surface state. One of these compounds, Bi2Se2Te, shows tunable surface state dispersion upon its electronic alloying with Sb (SbxBi2-xSe2Te series). Other members of the ternary family such as GeBi2Te4 and BiTe1.5S1.5 show an in-gap surface Dirac point, the former of which has been predicted to show nonzero weak topological invariants such as (1;111); thus belonging to a different topological class than BiTe1.5S1.5. The measured band structure presented here will be a valuable guide for interpreting transport, thermoelectric, and thermopower measurements on these compounds. The unique surface band topology observed in these compounds contributes towards identifying designer materials with desired flexibility needed for thermoelectric and spintronic device fabrication.
M. Neupane and S. Xu and L. A. Wray and A. C. Petersen and R. Shankar and N. Alidoust and C. Liu and A. V. Fedorov and H. Ji and J. M. Allred and Y. S. Hor and T. Chang and H. Jeng and H. Lin and A. Bansil and R. J. Cava and M. Z. Hasan, "Topological Surface States and Dirac Point Tuning in Ternary Topological Insulators," Physical review B: Condensed matter and materials physics, vol. 85, no. 23, American Physical Society (APS), Jun 2012.
The definitive version is available at https://doi.org/10.1103/PhysRevB.85.235406
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© 2012 American Physical Society (APS), All rights reserved.
01 Jun 2012