SKM 2021 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 25: Poster Session: Topology
TT 25.6: Poster
Donnerstag, 30. September 2021, 13:30–16:00, P
Impurity-induced bound states and resonances in lattice Dirac-Weyl semimetals — •João P. Santos Pires1, Bruno Amorim2, and João M. Viana Parente Lopes1 — 1Centro de Física das Universidades do Minho e Porto, University of Porto, 4169-007 Porto, Portugal — 2Centro de Física das Universidades do Minho e Porto, University of Minho, 4710-057 Braga, Portugal
The discovery of gapless 3D semimetals turned Dirac-Weyl electrons into a hot topic in condensed matter. The possibility of a putative impurity- or disorder-driven quantum phase transition that turns a semi-metallic phase (with vanishing DoS at the Fermi level) into a diffusive metallic phase have attracted particular interest. Despite the vast number of recent work addressing this problem, the picture remains unclear and seemingly dependent on the precise type of disorder considered.
In this work, we use a projected Green function method to study a four-band gapless Dirac Hamiltonian discretised in a simple cubic lattice, and in the presence of impurities composed of spherical clusters with on-site energy U. With this method, we evaluate the correction to the total and local density of states induced by the impurity. For cluster of radius larger than one lattice spacing, we found that eigenstates bound to the impurity cluster are formed, at fine-tuned values of U that depart from the predictions from the continuum theory. As this radius is increased, the lattice results progress towards the continuum theory predictions.