– Dependency on the Crystallinity*

The true nature of the topological surface states (TSS) in SmB₆ still remains to be unveiled, despite intensive research [1]. Our previous tunneling study [2] not only found evidence for surface Dirac cones but also unraveled their intriguing topological nature due to the inherent interaction [3] with spin excitons [4]. Extended to Sm-deficient single crystals, it now reveals how their evolution is influenced delicately by such interaction depending on the crystallinity [5]. Seemingly contradictory to the anticipated topological protection, this can be understood by considering the interplay between strong correlations and topological effects. We will present how the temperature evolution of tunneling conductance differs and discuss how spin excitons influence the emergence of coherent TSS. [1] M. Dzero et al., Annu. Rev. Condens. Matter Phys. 7, 249 (2016). [2] W. K. Park et al., PNAS 113, 6599 (2016); L. Sun et al., PRB 95, 195129 (2017). [3] W. T. Fuhrman et al., PRL 114, 036401 (2015). [4] G. A. Kapilevich et al., PRB 92, 085113 (2015). [5] M. E. Valentine et al., arXiv:1712.01325v1.