2012/05/14 by Yang Wang, Victor W. Brar, A. V. Shytov +9 · 135 citations
Materials Science · Physics and Astronomy · #Condensed matter physics #Coulomb #Dirac (video compression format) #Dirac fermion #Graphene #Graphene research and applications #Impurity #Physics #Quantum and electron transport phenomena #Quantum mechanics #Quasiparticle #Superconductivity #Topological Materials and Phenomena #cond-mat.mes-hall
paper · pdf · doi:10.1038/nphys2379
published in Nature Physics 8(9), 653-657 (Nature Portfolio)
arxiv created 2012/05/14 · openalex publication_date 2012/07/29 · arxiv updated 2013/05/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The response of Dirac fermions to a Coulomb potential is predicted to differ significantly from the behavior of non-relativistic electrons seen in traditional atomic and impurity systems. Surprisingly, many key theoretical predictions for this ultra-relativistic regime have yet to be tested in a laboratory. Graphene, a 2D material in which electrons behave like massless Dirac fermions, provides a unique opportunity to experimentally test such predictions. The response of Dirac fermions to a Coulomb potential in graphene is central to a wide range of electronic phenomena and can serve as a sensitive probe of graphene's intrinsic dielectric constant, the primary factor determining the strength of electron-electron interactions in this material. Here we present a direct measurement of the nanoscale response of Dirac fermions to a single Coulomb potential placed on a gated graphene device. Scanning tunneling microscopy and spectroscopy were used to fabricate tunable charge impurities on graphene and to measure how they are screened by Dirac fermions for a Q = +1|e| impurity charge state. Electron-like and hole-like Dirac fermions were observed to respond very differently to tunable Coulomb potentials. Comparison of this electron-hole asymmetry to theoretical simulations has allowed us to test basic predictions for the behavior of Dirac fermions near a Coulomb potential and to extract the intrinsic dielectric constant of graphene: εg= 3.0 ± 1.0. This small value of εg indicates that microscopic electron-electron interactions can contribute significantly to graphene properties.