Affiliation:
1. Weizmann Institute of Science
2. McGill University
3. Max Planck Institute for Chemical Physics of Solids
Abstract
Strong singularities in the electronic density of states amplify correlation effects and play a key role in determining the ordering instabilities in various materials. Recently high order van Hove singularities (VHSs) with diverging power-law scaling have been classified in single-band electron models. We show that the 110 surface of Bismuth exhibits high order VHS with an usually high density of states divergence \sim (E)^{-0.7}∼(E)−0.7. Detailed mapping of the surface band structure using scanning tunneling microscopy and spectroscopy combined with first-principles calculations show that this singularity occurs in close proximity to Dirac bands located at the center of the surface Brillouin zone. The enhanced power-law divergence is shown to originate from the anisotropic flattening of the Dirac band just above the Dirac node. Such near-coexistence of massless Dirac electrons and ultra-massive saddle points enables to study the interplay of high order VHS and Dirac fermions.
Funder
Fonds de Recherche du Québec - Nature et Technologies
German-Israeli Foundation for Scientific Research and Development
Israel Science Foundation
Natural Sciences and Engineering Research Council
Weizmann Institute of Science
Subject
General Physics and Astronomy