Local Electronic Structure around a Single Impurity in an Anderson Lattice Model for Topological Kondo Insulators

摘要

Shortly after the discovery of topological band insulators, the topologicalKondo insulators (TKIs) have also been theoretically predicted. The latter hasignited revival interest in the properties of Kondo insulators. Currently, thefeasibility of topological nature in SmB$_6$ has been intensively analyzed byseveral complementary probes. Here by starting with a minimal-orbital Andersonlattice model, we explore the local electronic structure in a Kondo insulator.We show for the first time that the two strong topological regimes sandwichingthe weak topological regime give rise to a single Dirac cone, which is locatednear the center or corner of the surface Brillouin zone. We further find that,when a single impurity is placed on the surface, low-energy resonance statesare induced in the weak scattering limit for the strong TKI regimes and theresonance level moves monotonically across the hybridization gap with thestrength of impurity scattering potential; while low energy states can only beinduced in the unitary scattering limit for the weak TKI regime, where theresonance level moves universally toward the center of the hybridization gap.These impurity induced low-energy quasiparticles will lead to characteristicsignatures in scanning tunneling microscopy/spectroscopy, which has recentlyfound success in probing into exotic properties in heavy fermion systems.