Imaging electrostatically confined Dirac fermions in graphene quantum dots
Name
Levitov_Imaging electrostatically confined.pdf
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2.88 MB
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Author(s)
Lee, Juwon
Wong, Dillon
Velasco Jr, Jairo
Kahn, Salman
Tsai, Hsin-Zon
Taniguchi, Takashi
Watanabe, Kenji
Zettl, Alex
Wang, Feng
Crommie, Michael F.
Date Issued
June 2016
Journal
Nature Physics
Publisher
Nature Publishing Group
Citation
Lee, Juwon et al. “Imaging Electrostatically Confined Dirac Fermions in Graphene Quantum Dots.” Nature Physics 12.11 (2016): 1032–1036.
Version
Original manuscript
Abstract
Electrostatic confinement of charge carriers in graphene is governed by Klein tunnelling, a relativistic quantum process in which particle–hole transmutation leads to unusual anisotropic transmission at p–n junction boundaries. Reflection and transmission at these boundaries affect the quantum interference of electronic waves, enabling the formation of novel quasi-bound states. Here we report the use of scanning tunnelling microscopy to map the electronic structure of Dirac fermions confined in quantum dots defined by circular graphene p–n junctions. The quantum dots were fabricated using a technique involving local manipulation of defect charge within the insulating substrate beneath a graphene monolayer13. Inside such graphene quantum dots we observe resonances due to quasi-bound states and directly visualize the quantum interference patterns arising from these states. Outside the quantum dots Dirac fermions exhibit Friedel oscillation-like behaviour. Bolstered by a theoretical model describing relativistic particles in a harmonic oscillator potential, our findings yield insights into the spatial behaviour of electrostatically confined Dirac fermions.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1038/nphys3805
