  There has been considerable interest in exploiting the spin degrees of
freedom of electrons for potential information storage and computing
technologies. Topological insulators (TI), a class of quantum materials, have
special gapless edge/surface states, where the spin polarization of the Dirac
fermions is locked to the momentum direction. This spin-momentum locking
property gives rise to very interesting spin-dependent physical phenomena such
as the Edelstein and inverse Edelstein effects. However, the spin injection in
pure surface states of TI is very challenging because of the coexistence of the
highly conducting bulk states. Here, we experimentally demonstrate the spin
injection and observe the inverse Edelstein effect in the surface states of a
topological Kondo insulator, SmB6. At low temperatures when only surface
carriers are present, a clear spin signal is observed. Furthermore, the
magnetic field angle dependence of the spin signal is consistent with
spin-momentum locking property of surface states of SmB6.
