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Graphene Quantum Dots Probed by Scanning Tunneling Microscopy

Morgenstern, Markus and Freitag, Nils and Nent, Alexander and Nemes Incze, Péter and Liebmann, Marcus (2017) Graphene Quantum Dots Probed by Scanning Tunneling Microscopy. ANNALEN DER PHYSIK, 529 (11). pp. 1-9. ISSN 0003-3804

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Abstract

Scanning tunneling spectroscopy results probing the electronic properties of graphene quantum dots are reviewed. After a short summary of the study of squared wave functions of graphene quantum dots on metal substrates, we firstly present data where the Landau level gaps caused by a perpendicular magnetic field are used to electrostatically confine electrons in monolayer graphene, which are probed by the Coulomb staircase revealing the consecutive charging of a quantum dot. It turns out that these quantum dots exhibit much more regular charging sequences than lithographically confined ones. Namely, the consistent grouping of charging peaks into quadruplets, both, in the electron and hole branch, portrays a regular orbital splitting of about 10meV. At low hole occupation numbers, the charging peaks are, partly, additionally grouped into doublets. The spatially varying energy separation of the doublets indicates a modulation of the valley splitting by the underlying BN substrate. We outline that this property might be used to eventually tune the valley splitting coherently. Afterwards, we describe graphene quantum dots with multiple contacts produced without lithographic resist, namely by local anodic oxidation. Such quantum dots target the goal to probe magnetotransport properties during the imaging of the corresponding wave functions by scanning tunneling spectroscopy.

Item Type: Article
Uncontrolled Keywords: MAGNETIC-FIELDS; ROOM-TEMPERATURE; TUNABLE GRAPHENE; DIRAC FERMIONS; SINGLE-ELECTRON; MONOLAYER GRAPHENE; Bilayer graphene; LOCAL ANODIC-OXIDATION; ATOMIC-FORCE MICROSCOPE; HEXAGONAL BORON-NITRIDE; local anodic oxidation; valley splitting; scanning tunneling microscopy; GRAPHENE QUANTUM DOTS
Subjects: Q Science / természettudomány > QC Physics / fizika
SWORD Depositor: MTMT SWORD
Depositing User: MTMT SWORD
Date Deposited: 07 Jan 2018 09:52
Last Modified: 07 Jan 2018 09:52
URI: http://real.mtak.hu/id/eprint/72102

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