CM - AMO SEMINAR | Unraveling Intriguing Topological Nature of the Kondo Insulator SmB6

Samarium hexaboride (SmB6), a well-known Kondo insulator, has drawn a great deal of attention owing to its possibly topological nature harboring protected surface states [1]. Despite numerous investigations, corroborative spectroscopic evidences for such states are still lacking unlike in the weakly correlated counterparts. We adopt planar tunneling spectroscopy to unveil their topological nature by utilizing its inherently high energy resolution as well as high momentum selectivity [2]. In this talk, after giving a general introduction, I will present tunneling conductance spectra obtained from two different crystallographic surfaces. Detailed features due to the surface states as well as the bulk gap opening will be discussed. Most importantly, I’ll show how the intriguing nature of the topological surface states is uncovered via inelastic tunneling processes that involve their interaction with collective bulk excitations, spin excitons. After presenting a comparison of our findings with a recent theoretic proposal [3], I will conclude by discussing implications on generic topological materials whose ground states are governed by strong correlations.

[1] M. Dzero et al., Phys. Rev. Lett. 104, 106408 (2010).
[2] W. K. Park et al., submitted.
[3] G. A. Kapilevich et al., Phys. Rev. B 92, 085133 (2015).