  The Kondo insulator SmB6 has long been known to exhibit low temperature
transport anomalies whose origin is of great interest. Here we uniquely access
the surface electronic structure of the anomalous transport regime by combining
state-of-the-art laser- and synchrotron-based angle-resolved photoemission
techniques. We observe clear in-gap states (up to 4 meV), whose temperature
dependence is contingent upon the Kondo gap formation. In addition, our
observed in-gap Fermi surface oddness tied with the Kramers' points topology,
their coexistence with the two-dimensional transport anomaly in the Kondo
hybridization regime, as well as their robustness against thermal recycling,
taken together, collectively provide by-far the strongest evidence for
protected surface metallicity with a Fermi surface whose topology is consistent
with the theoretically predicted topological surface Fermi surface (TSS). Our
observations of systematic surface electronic structure provide the fundamental
electronic parameters for the anomalous Kondo ground state of the correlated
electron material SmB6.
