Spin-resolved electronic properties of clean and doped thin-film topological insulators
This project will combine our expertise in scanning tunneling spectroscopy with the unique capabilities in molecular beam epitaxy (MBE) available within this SFB to investigate the (spin-resolved) electronic structure of 2D topological insulators. Thereby, we will be able circumvent the limitations implicated with conventional bulk V2VI3 materials. In cooperation with the MBE projects A04 (Brüne/Molenkamp), A05 (Brunner), and B01 (Brunner/Kamp), and projects A01 (Bentmann/Reinert) and A08 (Schäfer/Claessen) that employ complementary surface sensitive techniques for electronic characterization, we will develop a dedicated in vacuo sample transfer mechanism that allows the growth and analysis of three-dimensional (3D) and two-dimensional (2D) thin film topological (crystalline) insulators and subsequent sample analysis – including atomic scale characterization with local probes – without the drawbacks of exposure to ambient conditions. Thereby, we will be able to perform scanning tunneling spectroscopy and quasi-particle interference experiments on (i) optimized epitaxial V2VI3 materials (B01), (ii) topological crystalline insulator films, such as Pb1−xSnxTe (A05), and (iii) on the two-dimensional topological insulator HgTe which has been the prototype for this material class (A04). These materials will be magnetically doped during growth (bulk doping) or after growth inside our low-temperature STMs (surface doping). Our real space investigations with atomic resolution capability will be performed on exactly the same samples that are also studied by complementary spatially averaging methods, such as angle-resolved photoemission spectroscopy (ARPES) (A01, A08) and transport measurements (A03). We expect the direct comparison of these data leads to a deeper understanding of the peculiar electronic properties of topological insulators, and eventually to band structures which can be spin- and charge-engineered for device applications.
[A02.1] P. Sessi, M. M. Otrokov, T. Bathon, M. G. Vergniory, K. A. Kokh, O. E. Tereshchenko, E. V. Chulkov, and M. Bode: Visualizing Spin-Dependent Bulk Scattering and Break-Down of the Linear Dispersion Relation in Bi2Te3, Phys. Rev. B 88, 161407 (2013).