Title
Realization of a tunable artificial atom at a supercritically charged vacancy in grapheneRealization of a tunable artificial atom at a supercritically charged vacancy in graphene
Author
Faculty/Department
Faculty of Sciences. Physics
Research group
Condensed Matter Theory
Publication type
article
Publication
Subject
Physics
Source (journal)
Nature physics
Volume/pages
12(2016):6, p. 545-549
ISSN
1745-2473
ISI
000377475700011
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
Graphene's remarkable electronic properties have fuelled the vision of a graphene-based platform for lighter, faster and smarter electronics and computing applications. One of the challenges is to devise ways to tailor graphene's electronic properties and to control its charge carriers(1-5). Here we show that a single-atom vacancy in graphene can stably host a local charge and that this charge can be gradually built up by applying voltage pulses with the tip of a scanning tunnelling microscope. The response of the conduction electrons in graphene to the local charge is monitored with scanning tunnelling and Landau level spectroscopy, and compared to numerical simulations. As the charge is increased, its interaction with the conduction electrons undergoes a transition into a supercritical regime(6-11) where itinerant electrons are trapped in a sequence of quasi-bound states which resemble an artificial atom. The quasi-bound electron states are detected by a strong enhancement of the density of states within a disc centred on the vacancy site which is surrounded by halo of hole states. We further showthat the quasi-bound states at the vacancy site are gate tunable and that the trapping mechanism can be turned on and off, providing a mechanism to control and guide electrons in graphene.
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