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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• Heavy surface state in a possible topological Kondo insulator: Magneto-thermoelectric transport on the (011)-plane of SmB${}_6$
• Composition-spread Growth and the Robust Topological Surface State of Kondo insulator SmB6 Thin Films
• End states in a 1-D topological Kondo insulator
• Scanning tunneling spectroscopy and surface quasiparticle interference in models for the strongly correlated topological insulators SmB6 and PuB6
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• Theory of Point Contact Spectroscopy in Correlated Materials
• Two distinct topological phases in the mixed valence compound YbB6 and its differences from SmB6
• Two-dimensional heavy fermions on the strongly correlated boundaries of Kondo topological insulators
• A Strongly-Interacting Dirac Liquid on the Surface of a Topological Kondo Insulator
• Topological Phases in Oxide Heterostructures with Light and Heavy Transition Metal Ions
• Magnetic end-states in a strongly-interacting one-dimensional topological Kondo insulator
• ARPES insights on the metallic states of YbB6(001): E(k) dispersion, temporal changes and spatial variation
• Topological phase in a two-dimensional metallic heavy-fermion system
• Vortices and vortex states in Rashba spin-orbit-coupled condensates
• Optical conductivity of topological Kondo insulating states
• Exactly solvable 2D topological Kondo lattice model
• Many-Body Effects in Topological Kondo Insulators
• Pressure studies of the quantum critical alloy Ce(0.93)Yb(0.07)CoIn5