Spectroscopic nature of the topological Kondo insulator SmB₆

Samarium hexaboride (SmB₆), a well-known Kondo insulator, has recently received great deal of attention due to the possibility of being a correlated topological insulator. Despite numerous experimental findings supportive of this possibility, its detailed spectroscopic properties remain to be elucidated. Our recent tunneling spectroscopy based on planar junctions on SmB₆ [1, 2] has not only found evidence for the existence of multiple surface Dirac fermions, in agreement with a quantum oscillation study as well as theoretical predictions, but also revealed their intriguing topological nature affected by the interaction with bulk excitations, called spin excitons [3]. We will present tunneling conductance spectra for two different surface orientations as a function of temperature and magnetic field and discuss the implications of our results. In particular, we will focus on some of the outstanding open questions in relation to our findings. [1] W. K. Park et al., Proc. Natl. Acad. Sci. U. S. A. 113, 6599 (2016); [2] L. Sun et al., Phys. Rev. B 95, 195129 (2017); [3] G. A. Kapilevich et al., Phys. Rev. B 92, 085133 (2015).