Resonance states and beating pattern induced by quantum impurity scattering in Weyl/Dirac semimetals

Abstract

Currently, Weyl semimetals (WSMs) are drawing great interest as a new topological nontrivial phase. When most of the studies concentrated on the clean host WSMs, it is expected that the dirty WSM system would present rich physics due to the interplay between the WSM states and the impurities embedded inside these materials. We investigate theoretically the change of local density of states in three-dimensional Dirac and Weyl bulk states scattered off a quantum impurity. It is found that the quantum impurity scattering can create nodal resonance and Kondo peak/dip in the host bulk states, remarkably modifying the pristine spectrum structure. Moreover, the joint effect of the separation of Weyl nodes and the Friedel interference oscillation causes the unique battering feature. We in detail an- alyze the different contribution from the intra- and inter-node scattering processes and present various scenarios as a consequence of competition between them. Importantly, these behaviors are sensitive significantly to the displacement of Weyl nodes in energy or momentum, from which the distinctive fingerprints can be extracted to identify various semimetal materials experimentally by employing the scanning tunneling microscope.

Spatial charge inhomogeneity and defect states in topological Dirac semimetal thin films of Na 3 Bi

“…This phenomenon has also been observed for defects in graphene ( 19 ), dopants in semiconductors ( 20 , 21 ), and topological insulator systems ( 22 ) as a tip-induced “ionization charging ring,” where the sudden increase in charge of a bound defect state at a particular tip potential affects the screening cloud in the substrate at the tip position. In this case, the defect state is truly localized, in contrast to the quasi-bound state observed for single Na vacancies, and offers an opportunity to study a quantum dot connected to a TDS reservoir, an area of significant theoretical interest ( 26 – 28 ).…”

Chiral magnetic chemical bonds in molecular states of impurities in Weyl semimetals

“…One of the aspects of Weyl semimetals which recently received particular attention is the peculiar impurity physics [20][21][22][23][24][25]. In the present work, we clarify the role played by chirality of Weyl quasiparticles in the processes of impurity scattering by investigation of the local density of states.…”

Electrically tunable Kondo effect as a direct measurement of the chiral anomaly in disorder Weyl semimetals

“…40,41 . Specifically, we use the Anderson model [28][29][30][31][32]34,36,39,42 to characterize the quantum impurities, i.e.,…”

“…With the impurity level approaching the Fermi level, an additional sharp peak emerges to decorate the Lorenz resonance peak when the temperature is below a critical value T K . This sharp peak, in fact, is attributable to the Kondo effect, which has been widely studied in varied systems [28][29][30][31][32][33][34][35][36][37][38][39]42 . The Kondo peak comes from the spin fluctuation at the Fermi level, which apart from the temperature, is very sensitive to the location of the Fermi level.…”