Observation of possible topological in-gap surface states in the Kondo insulator SmB$_{6}$ by photoemission

SmB$_{6}$, a well known Kondo insulator, exhibits transport anomaly at low temperature which is usually attributed to some ``in-gap'' states. While recent theoretical calculations and transport measurements suggest that these in-gap states could be ascribed to topological surface states. SmB$_{6}$ thus might be the first realization of topological Kondo insulator (TKI). Here by performing angle-resolved photoemission spectroscopy (ARPES), we directly observed several dispersive states within the hybridization gap of SmB$_{6}$, which show negligible k$_{z}$ dependence, indicative of their surface origin. Furthermore, the photoemission circular dichroism of the in-gap states suggests the chirality of the orbital angular momentum, and these states vanish simultaneously with the hybridization gap around 150 K. These all strongly suggest their possible topological origin.