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Center for Nonlinear Studies |
Samarium hexaboride (SmB6), a well-known Kondo insulator, has received a great deal of attention owing to its topological nature [1]. Despite intensive research in recent years, its detailed spectroscopic properties remain to be unraveled. Our recent tunneling spectroscopy [2, 3] based on planar junctions on stoichiometric crystals has not only revealed evidences for the existence of multiple bands of surface Dirac fermions but also provided a crucial piece of information regarding their topological nature, namely, their inherent interaction with bulk excitations, spin excitons [4, 5]. We have extended this investigation into crystals with Sm deficiencies. Although they also show some qualitatively similar features such as bulk hybridization gap, the surface states exhibit a quite different temperature evolution, in particular, without forming coherent states at low temperature. This suggests that the detailed topological nature in SmB6 could vary widely depending on the crystallinity. In this talk, I will present these results and also discuss the implications of our findings in the context of topological robustness in correlated phases. [1] M. Dzero et al., Phys. Rev. Lett. 104, 106408 (2010). [2] W. K. Park et al., Proc. Natl. Acad. Sci. U. S. A. 113, 6599 (2016). [3] L. Sun et al., Phys. Rev. B 95, 195129 (2017). [4] W. T. Fuhrman et al., Rev. Lett. 114, 036401 (2015). [5] G. A. Kapilevich et al., Phys. Rev. B 92, 085113 (2015). This work was performed in collaboration with, S. Liu, J. Sittler, and L. H. Greene at FSU, D.-J. Kim and Z. Fisk at University of California – Irvine (UCI), W. T. Fuhrman, J. Chamorro, S. Koohpayeh, W. A. Phelan, and T. M. McQueen at Johns Hopkins University (JHU). The work at FSU was supported by the US NSF/DMR-1704712. A portion of this work was performed at the NHMFL, which is supported by NSF Cooperative Agreement No. DMR-1644779 and the State of Florida. The work at UCI was supported by the US NSF/DMR-0801253. The work at JHU was supported by the US DOE grant DE-FG02-08ER46544
Host: Marcelo Jaime