LIGHT-SCATTERING FROM GAP EXCITATIONS AND BOUND-STATES IN SMB6

Gap formation and in-gap bound states are investigated in SmB6 using Raman scattering. Below 70 K, we observe an abrupt suppression of electronic scattering below similar to 290 cm(-1) that is not consistent with the predicted temperature dependence of a hybridization gap. We also find that gap formation in SmB6 is associated with the appearance of a sharp E(8)(Gamma(3)(+)) symmetry 130-cm(-1) excitation. We discuss several possible interpretations of this excitation, including a Gamma(7)-Gamma(8) crystal-field transition and a transition between bound 4f(5)5d configurations.