Type: Article
Publication Date: 2016-02-19
Citations: 44
DOI: https://doi.org/10.1038/srep20860
Abstract Recent theoretical and experimental findings suggest the long-known but not well understood low temperature resistance plateau of SmB 6 may originate from protected surface states arising from a topologically non-trivial bulk band structure having strong Kondo hybridization. Yet others have ascribed this feature to impurities, vacancies and surface reconstructions. Given the typical methods used to prepare SmB 6 single crystals, flux and floating-zone procedures, such ascriptions should not be taken lightly. We demonstrate how compositional variations and/or observable amounts of impurities in SmB 6 crystals grown using both procedures affect the physical properties. From X-ray diffraction, neutron diffraction and X-ray computed tomography experiments we observe that natural isotope containing (SmB 6 ) and doubly isotope enriched ( 154 Sm 11 B 6 ) crystals prepared using aluminum flux contain co-crystallized, epitaxial aluminum. Further, a large, nearly stoichiometric crystal of SmB 6 was successfully grown using the float-zone technique; upon continuing the zone melting, samarium vacancies were introduced. These samarium vacancies drastically alter the resistance and plateauing magnitude of the low temperature resistance compared to stoichiometric SmB 6 . These results highlight that impurities and compositional variations, even at low concentrations, must be considered when collecting/analyzing physical property data of SmB 6 . Finally, a more accurate samarium-154 coherent neutron scattering length, 8.9(1) fm, is reported.