Surface and Bulk Electronic Structure of the Strongly Correlated System SmB$_{6}$ and Implications for a Topological Kondo Insulator

Understand

Recent theoretical calculations and experimental results suggest that the strongly correlated material SmB$_{6}$ may be a realization of a topological Kondo insulator.

• We have performed an angle-resolved photoemission spectroscopy study on SmB$_{6}$ in order to elucidate elements of the electronic structure relevant to the possible occurrence of a topological Kondo insulator state.
• The obtained electronic structure in the whole three-dimensional momentum space reveals one electron-like 5d bulk band centred at the X point of the bulk Brillouin zone that is hybridized with strongly correlated f electrons, as well as the opening of a Kondo bandgap ($\Delta_B$ $\sim$ 20 meV) at low temperature.
• In addition, we observe electron-like bands forming three Fermi surfaces at the center $\bar{\Gamma}$ point and boundary $\bar{X}$ point of the surface Brillouin zone.