Non-trivial surface states of samarium hexaboride at the (111) surface.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31127112.
- Also identified by DOI 10.1038/s41467-019-10353-3 and PMC identifier 6534584.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The peculiar metallic electronic states observed in the Kondo insulator, samarium hexaboride (SmB<sub>6</sub>), has stimulated considerable attention among those studying non-trivial electronic phenomena. However, experimental studies of these states have led to controversial conclusions mainly due to the difficulty and inhomogeneity of the SmB<sub>6</sub> crystal surface. Here, we show the detailed electronic structure of SmB<sub>6</sub> with angle-resolved photoelectron spectroscopy measurements of the three-fold (111) surface where only two inequivalent time-reversal-invariant momenta (TRIM) exist. We observe the metallic two-dimensional state was dispersed across the bulk Kondo gap. Its helical in-plane spin polarisation around the surface TRIM indicates that SmB<sub>6</sub> is topologically non-trivial, according to the topological classification theory for weakly correlated systems. Based on these results, we propose a simple picture of the controversial topological classification of SmB<sub>6</sub>.