Heavy surface state in a possible topological Kondo insulator: Magnetothermoelectric transport on the (011) plane of SmB6

Motivated by the high sensitivity to Fermi surface topology and scattering mechanisms in magnetothermoelectric transport, we have measured the thermopower and Nernst effect on the (011) plane of the proposed topological Kondo insulator SmB6. These experiments, together with electrical resistivity and Hall effect measurements, suggest that the (011) plane also harbors a metallic surface with an effective mass on the order of 10-10(2) m(0). The surface and bulk conductances are well distinguished in these measurements and are categorized into metallic and nondegenerate semiconducting regimes, respectively. Electronic correlations play an important role in enhancing scattering and also contribute to the heavy surface state.