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Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
Phonon-mediated tunneling into graphene
T O Wehling1, I Grigorenko, A I Lichtenstein
1I. Institut für Theoretische Physik, Universität Hamburg, Jungiusstrasse 9, D-20355 Hamburg, Germany.
Physical Review Letters
|December 31, 2008
Summary
This study explains the unexpected graphene energy gap observed in experiments. Phonon-mediated tunneling, involving electron-phonon interactions, is confirmed as the cause of this gap.
Area of Science:
- Condensed Matter Physics
- Materials Science
Background:
- Scanning tunneling spectroscopy experiments revealed an unexpected energy gap (~60 meV) around the Fermi level in graphene.
- This observation prompted theoretical investigations to understand the underlying physical mechanisms.
Purpose of the Study:
- To theoretically investigate the experimentally observed energy gap in graphene.
- To confirm phonon-mediated tunneling as the cause of the observed spectral gap.
Main Methods:
- Ab initio theory was employed to study the real-space properties of wave functions involved in tunneling.
- A model for electron-phonon interaction was developed, coupling Dirac electrons with quasifree-electron states.
- The self-energy associated with electron-phonon interaction was calculated.
Main Results:
- The theoretical model successfully explains the experimentally observed spectra in graphene.
- The calculated tunneling density of states shows good agreement with experimental dI/dU spectra.
- Phonon-mediated tunneling is confirmed as the mechanism responsible for the graphene energy gap.
Conclusions:
- The study provides a theoretical explanation for the observed graphene energy gap.
- Electron-phonon interaction is identified as the key mechanism driving the gap formation.
- The findings reconcile experimental observations with theoretical understanding of tunneling in graphene.
