title: Topological surface states interacting with bulk excitations in the Kondo insulator SmB6 revealed via planar tunneling spectroscopy.
abstract: Samarium hexaboride (SmB6), a well-known Kondo insulator in which the insulating bulk arises from strong electron correlations, has recently attracted great attention owing to increasing evidence for its topological nature, thereby harboring protected surface states. However, corroborative spectroscopic evidence is still lacking, unlike in the weakly correlated counterparts, including Bi2Se3 Here, we report results from planar tunneling that unveil the detailed spectroscopic properties of SmB6 The tunneling conductance obtained on the (001) and (011) single crystal surfaces reveals linear density of states as expected for two and one Dirac cone(s), respectively. Quite remarkably, it is found that these topological states are not protected completely within the bulk hybridization gap. A phenomenological model of the tunneling process invoking interaction of the surface states with bulk excitations (spin excitons), as predicted by a recent theory, provides a consistent explanation for all of the observed features. Our spectroscopic study supports and explains the proposed picture of the incompletely protected surface states in this topological Kondo insulator SmB6.
authors.affiliation: Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801; wkpark@illinois.edu lhgreene@magnet.fsu.edu.
authors.forename: Wan Kyu
authors.initials: WK
authors.lastname: Park
authors.affiliation: Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801;
authors.forename: Lunan
authors.initials: L
authors.lastname: Sun
authors.affiliation: Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801;
authors.forename: Alexander
authors.initials: A
authors.lastname: Noddings
authors.affiliation: Department of Physics and Astronomy, University of California, Irvine, CA 92697.
authors.forename: Dae-Jeong
authors.initials: DJ
authors.lastname: Kim
authors.affiliation: Department of Physics and Astronomy, University of California, Irvine, CA 92697.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Fisk
authors.affiliation: Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801; wkpark@illinois.edu lhgreene@magnet.fsu.edu.
authors.forename: Laura H
authors.initials: LH
authors.lastname: Greene
mesh_terms: D001896:Boron Compounds / Q000737:chemistry*; D012493:Samarium / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D001896:Boron Compounds; D012493:Samarium
keywords: inelastic tunneling; planar tunneling spectroscopy; samarium hexaboride; spin excitons; topological Kondo insulator