Impurity-induced resonant states in topological nodal-line semimetals

Abstract

Nodal-line semimetals are characterized by a kind of topologically nontrivial bulk-band crossing, giving rise to almost flat surface states. Yet, a direct evidence of the surface states is still lacking. Here we study theoretically impurity effects in topological nodal-line semimetals based on the Tmatrix method. It is found that for a bulk impurity, some in-gap states may be induced near the impurity site, while the visible resonant impurity state can only exist for certain strength of the impurity potentials. For a surface impurity, robust resonant impurity states exist in a wide range of impurity potentials. Such robust resonant states stem from the topological protected weak dispersive surface states, which can be probed by scanning tunneling microscopy, providing a strong signature of the topological surface states in the nodal-line semimetals.

Projective quasiparticle interference of a single scatterer to analyze the electronic band structure of ZrSiS

“…Although we cannot determine the different defect types yet, further exploration of the impurity spectrum may provide extra information for a later determination [54]. The most frequently found defects are the diamond-shaped Zr-site defect and the X-shaped S-site defect, which are expected to be located within the top ZrS bilayer.…”

Impurity effects in a two-dimensional nonsymmorphic Dirac semimetal

“…The effects of a single impurity on the system with Dirac spectrum have been extensively studied [64][65][66][67][68][69][70][71][72]. Previously the impurity effects have been widely used for understanding the nature of the quasiparticle spectra in various unconventional superconductors [73][74][75][76][77] and topological systems [78][79][80][81][82]. It is shown that the local density of states (LDOS) around a Dirac point of the electronic spectrum is significantly disrupted by a sufficiently large impurity perturbation [64].…”