A Consistent View of the Samarium Hexaboride Surface Terminations

Since the establishment of topological insulators, a lot of interest has turned to finding systems that combine topology with strong electron correlations. This led Dzero et al. to propose that Kondo insulators, materials that open a band gap by mixing local and itinerant states of opposite parity, should fall into this category [1]. The effort spurred by this proposal has advanced the state of knowledge on SmB₆, the leading candidate for a topological Kondo insulator [2]. The question of its topology, however, remains unanswered.

The apparently contradictory results from different experimental techniques form major obstacle to resolving this issue. In this paper we tackle one of these apparent contradictions: Researchers using scanning tunneling microscopy [3,4] have reached different conclusions on the surface terminations than those using photoemission spectroscopy [5]. By combining both techniques we find the results from these methods can be reconciled, a conclusion that will help settle this topical issue.

[1] M. Dzero et al., Phys. Rev. Lett. 104 (2010) 106408.
[2] J. W. Allen, Phil. Mag. 96 (2016) 3227.
[3] M. M. Yee et al., arxiv.org 1308.1085 (2013).
[4] S. Rößler et al., Proc. Natl. Acad. Sci. 111 (2014) 4798.
[5] P. Hlawenka et al., Nat. Commun. 9 (2018) 517.