Infrared Optical Conductivity of Bulk Bi₂Te₂Se

id- and near-infrared measurements reveal that the optical conductivity of the three-dimensional topological insulator, Bi₂Te₂Se, is dominated by bulk carriers and shows a linear-in-frequency increase at 0.5 to 0.8 eV. This linearity might be interpreted as a signature of three-dimensional (bulk) Dirac bands; however, band-structure calculations show that transitions between bands with complex dispersion contribute instead to the inter-band optical conductivity at these frequencies and, hence, the observed linearity is accidental. These results warn against the oversimplified interpretations of optical-conductivity measurements in different Dirac materials

Effect of Sr Doping on Structural and Transport Properties of Bi2Te3

Search for doped superconducting topological insulators is of prime importance for new quantum technologies. We report on fabrication of Sr-doped Bi2Te3 single crystals. We found that Bridgman grown samples have p-type conductivity in the low 1019 cm−3, high mobility of 4000 cm2V−1s−1, crystal structure independent on nominal dopant content, and no signs of superconductivity. We also studied molecular beam epitaxy grown SrxBi2−xTe3 films on lattice matched (1 1 1) BaF2 polar surface. Contrary to the bulk crystals thin films have n-type conductivity. Carrier concentration, mobility and c-lattice constant demonstrate pronounced dependence on Sr concentration x. Variation of the parameters did not lead to superconductivity. We revealed, that transport and structural parameters are governed by Sr dopants incorporation in randomly inserted Bi bilayers into the parent matrix. Thus, our data shed light on the structural position of dopant in Bi2Te3 and should be helpful for further design of topological insulator-based superconductors

Infrared Optical Conductivity of Bulk Bi2Te2Se

Ministry of Science and Higher Education of the Russian FederationRussian Science FoundationDeutsche Forschungsgemeinschaf

CeOmegaApp. Aplicación de gestión para academias

[ES] CeOmegaApp es una aplicación de gestión de clientes, empleados y contabilidad orientada a las necesidades de una academia PYME. Ha sido desarrollada en versión de escritorio bajo la tecnología de JavaFX. A lo largo del proyecto se va a ver el uso de los distintos conocimientos obtenidos durante el grado, desde SQL hasta toma de requisitos. A través del proyecto será posible ver los problemas a los que se puede enfrentar un desarrollador y analizar las tomas de decisiones frente a estas adversidades.[EN] CeOmegaApp is an application to manage customers, staff and accounting aimed to the necessities of a language school of the SME sector (Small and Medium Enterprise). This tool has been developed as a desktop version under JavaFX technology. All the knowledge acquired in the degree will be applied throughout the project, from SQL to taking requirements. The project makes possible to see all the problems that a developer may have to deal with and to analyse the decision making in the face of these adversities.Navarro García, J. (2018). CeOmegaApp. Aplicación de gestión para academias. http://hdl.handle.net/10251/112650TFG