Resolving the band structure of topological insulators and point-contact spectroscopy analysis

This study concerns a comprehensive quantitative analysis of topological insulators (TIs) [1], a new quantum state of matter, namely Bi$_{2}$Se$_{3}$. The first stage is observing the proximity-induced superconductivity effect [2] via point-contact spectroscopy (PCS). Differential conductance of the superconducting NbSe$_{2}$ crystal was measured at approximately 4 K, cooled with liquid helium. Through the analysis of I-V characteristics, it was possible to observe an expected behavior of differential conductance for voltages higher than 1 mV, and the ongoing work is to observe this effect at lower voltage. Subsequently, this method will be used to induce superconductivity in Bi$_{2}$Se$_{3}$ by combining it with NbSe$_{2}$. The second stage is a first-principles calculation of band structure of the TI crystal based on the density functional theory, DFT, performed on Bi$_{2}$Se$_{3}$ using the ABINIT program [3]. The third stage is resolving the band structure of the crystal via angle-resolved photoemission spectroscopy (ARPES) at a synchrotron facility and comparing with the above calculation. It is expected to be completed in February 2014. \\[4pt] [1] M. Z. Hasan et. al. Rev. Mod. Phys. 82, 3045 (2010).\\[0pt] [2] Zareapour, Parisa et. al. Nature Communications 3 (2012).\\[0pt] [3] Gonze, X. et al. Comput. Mater. Sci. 25, 478-492 (2002).