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Title
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Exciton states in a circular graphene quantum dot: Magnetic field induced intravalley to intervalley transition
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Author
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Abstract
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| The magnetic-field dependence of the energy spectrum, wave function, binding energy, and oscillator strength of exciton states confined in a circular graphene quantum dot (CGQD) is obtained within the configuration interaction method. We predict that (i) excitonic effects are very significant in the CGQD as a consequence of a combination of geometric confinement, magnetic confinement, and reduced screening; (ii) two types of excitons (intravalley and intervalley) are present in the CGQD because of the valley degree of freedom in graphene; (iii) the intravalley and intervalley exciton states display different magnetic-field dependencies due to the different electron-hole symmetries of the single-particle energy spectra; (iv) with increasing magnetic field, the exciton ground state in the CGQD undergoes an intravalley to intervalley transition accompanied by a change of angular momentum; (v) the exciton binding energy does not increase monotonically with the magnetic field due to the competition between geometric and magnetic confinements; and (vi) the optical transitions of the intervalley and intravalley excitons can be tuned by the magnetic field, and valley-dependent excitonic transitions can be realized in a CGQD. |
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Language
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English
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Source (journal)
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Physical review B / American Physical Society. - New York, N.Y, 2016, currens
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Publication
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New York, N.Y
:
American Physical Society
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2017
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ISSN
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2469-9969
[online]
2469-9950
[print]
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DOI
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10.1103/PHYSREVB.95.045409
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Volume/pages
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95
:4
(2017)
, 9 p.
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Article Reference
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045409
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ISI
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000391856000006
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Medium
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E-only publicatie
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Full text (Publisher's DOI)
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Full text (open access)
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