Hybridization, Inter-Ion Correlation, and Surface States in the Kondo Insulator SmB6

Abstract

As an exemplary Kondo insulator, SmB6 has been studied for several decades; however, direct evidence for the development of the Kondo coherent state and the evolution of the electronic structure in the material has not been obtained due to the rather complicated electronic and thermal transport behavior. Recently, these open questions attracted increasing attention as the emergence of a time-reversal invariant topological surface state in the Kondo insulator has been suggested. Here, we use point-contact spectroscopy to reveal the temperature dependence of the electronic states in SmB6. We demonstrate that SmB6 is a model Kondo insulator: below 100 K, the conductance spectra reflect the Kondo hybridization of Sm ions, but below ~ 30 K, signatures of inter-ion correlation effects clearly emerge. Moreover, we find evidence that the low-temperature insulating state of this exemplary Kondo lattice compound harbors conduction states on the surface, in support of predictions of nontrivial topology in Kondo insulators.

Accepted for publication in Physical Review X

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• Colloquium: Topological Band Theory
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• Observation of in-gap surface states in the Kondo insulator SmB6 by photoemission
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• Cubic Topological Kondo Insulators
• Symmetry Enforced Non-Abelian Topological Order at the Surface of a Topological Insulator
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• Fermi surface in the absence of a Fermi liquid in the Kondo insulator SmB${}_6$
• Kondo Breakdown in Topological Kondo Insulators
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• Driven Electronic States at the Surface of a Topological Insulator
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• Plutonium hexaboride is a correlated topological insulator
• Kondo hybridisation and the origin of metallic states at the (001) surface of SmB6
• Possible Weyl fermions in the magnetic Kondo system CeSb
• Correlation effects in (111) bilayers of perovskite transition-metal oxides
• Additional energy scale in SmB${}_6$ at low temperature
• Imaging emergent heavy Dirac fermions of a topological Kondo insulator
• Topological invariants, surface states, and interaction-driven phase transitions in correlated Kondo insulators with cubic symmetry
• Weak Antilocalization and Linear Magnetoresistance in The Surface State of SmB6
• Interaction-driven transition between topological states in a Kondo insulator
• Observation of perfect Andreev reflection due to Klein paradox in a topological superconducting state
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• Theory of Point Contact Spectroscopy in Correlated Materials
• Observation of the superconducting proximity effect in the surface state of SmB6 thin films
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• Two distinct topological phases in the mixed valence compound YbB6 and its differences from SmB6
• Experimental and theoretical study of the correlated compound YbCdSn: Evidence for large magnetoresistance and mass enhancement
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• Tunneling in heavy-fermion junctions
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• Electronic correlations and topology in Kondo insulator PuB${}_6$
• Colossal magnetoresistance in topological Kondo insulator