SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 59: Poster Session: Topology
TT 59.1: Poster
Donnerstag, 30. März 2023, 15:00–18:00, P2/OG4
Density-dependence of surface transport in tellurium-enriched nanograined bulk Bi2Te3 — •Sepideh Izadi1, Ahana Bhattacharya2, Sarah Salloum3, Stephan Schulz3, Martin Mittendorff2, and Gabi Schierning1 — 1Bielefeld University, Department of Physics, 33615 Bielefeld, Germany — 2University of Duisburg-Essen, Department of Physics, 47057 Duisburg, Germany — 3University of Duisburg-Essen, Department of Chemistry, 45141 Essen, Germany
Three-dimensional topological insulators (3D TI) demonstrate conventional parabolic bulk bands together with protected Dirac surface states. Bi2Te3 material is considered as a well-known 3D TI model, however, due to its complicated defect chemistry, high number of charge carriers in the bulk dominate transport signal, even as nanograined structures. Herein we introduce Te-enriched Bi2Te3 nanoparticles synthesis as a method to control the bulk charge carrier density. Therewith, defects-free and stoichiometric Bi2Te3 nanoparticles with sizes between 4 and 40 nm are synthesized using ionic-liquid based approach. Grain boundaries along Bi2Te3 facets are investigated using high resolution transmission electron microscopy (HRTEM). The resulting nanoparticles were compacted into nanograined pellets of varying porosity, thereby emphasizing the surface transport contribution. The nanograined pellets were characterized by a combination of electrical transport together with THz time-domain reflectivity measurements. Using the Hikami-Larkin-Nagaoka (HLN) model, a characteristic coherence length of 200 nm that is considerably larger than nanograins diameter is reported.