Signatures of charge inhomogeneities in the infrared spectra of topological insulators Bi2Se3, Bi2Te3 and Sb2Te3

• Published in: Journal of physics. Condensed matter Vol. 25; no. 7; p. 075501
• Main Authors: Dordevic, S V, Wolf, M S, Stojilovic, N, Lei, Hechang, Petrovic, C
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 20.02.2013; Institute of Physics
• Subjects: Antimony - chemistry; Bismuth - chemistry; Collective effects; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electric Conductivity; Electron states; Exact sciences and technology; Exchange, correlation, dielectric and magnetic functions, plasmons; Infrared and raman spectra and scattering; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other nonmetallic inorganics; Physics; Selenium - chemistry; Spectrophotometry, Infrared; Static Electricity; Tellurium - chemistry; Reflectivity; Bismuth selenides; Bismuth tellurides; Topological insulator; Plasmons; Inhomogeneity; Infrared spectra; Antimony tellurides; Optical conductivity
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/25/7/075501

We present the results of an infrared spectroscopy study of topological insulators Bi2Se3, Bi2Te3 and Sb2Te3. Reflectance spectra of all three materials look similar, with a well defined plasma edge. However, there are some important differences. Most notably, as temperature decreases the plasma edge shifts to lower frequencies in Bi2Se3, whereas in Bi2Te3 and Sb2Te3 it shifts to higher frequencies. In the loss function spectra we identify asymmetric broadening of the plasmon, and assign it to the presence of charge inhomogeneities. It remains to be seen if charge inhomogeneities are characteristic of all topological insulators, and whether they are of intrinsic or extrinsic nature.