Bi$_{2}$-Bi$_{2}$Se$_{3}$ Superlattice Materials Studied by Photoemission Spectroscopy

Although searches are carried out independently for new 2D quantum spin Hall or 3D topological materials for their robust, spin-polarized edge or surface conduction states, little has been done to experimentally show that both phases can coexist in a single material or explore how they may interact. The superlattice series Bi$_{\mathrm{2m}}$(Bi$_{2}$Se$_{3})_{\mathrm{n}}$, featuring stacked layers of Bi$_{2}$ and Bi$_{2}$Se$_{3}$, may contain systems where a combination of 2D and 3D topological phenomena should be at play, the latter of which can be identified by combined computational and spin-and angle-resolved photoemission spectroscopy studies. We find that several members of the series, (m$=$0, n$=$1), (m$=$1, n$=$1) and (m$=$2, n$=$1) have spin-chiral surface states at the center of the surface Brillouin zone, a trait of strong topological insulators. The characterization of the topological surface states will be discussed for these series members.