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Title: Theory of optical properties of graphene quantum dots
Authors: Özfidan, Işıl
Güçlü, Alev Devrim
Korkusinski, Marek
Hawrylak, Pawel
Keywords: Configuration interaction
Quantum dots
Optical spectra
Mean field
Magnetic moments
Issue Date: Jan-2016
Publisher: John Wiley and Sons Inc.
Source: Özfidan, I., Güçlü, A. D., Korkusinski, M., and Hawrylak, P. (2016). Theory of optical properties of graphene quantum dots. Physica Status Solidi - Rapid Research Letters, 10(1), 102-110. doi:10.1002/pssr.201510335
Abstract: We present here a theory of the optical properties of graphene quantum dots (GQDs) with tunable band gaps by lateral size confinement, from UV to THz. Starting from the Hartree-Fock ground state, we construct the correlated many-body ground and excited states of GQDs as a linear combination of a finite number of electron-hole pair excitations. We discuss the evolution of the band gap with size and its renormalization by self-energy and excitonic effects. We calculate and analyze the dipole moments of graphene quantum dots that possess a degenerate valence and conduction band edge, and construct a characteristic exciton and biexciton spectrum. We find an exciton band consisting of a pair of robust, spin singlet bright exciton states and a band of dark, spin singlet and spin triplet, exciton states at lower energies. We predict a characteristic band of biexciton levels at the band edge, discuss the Auger processes and identify a biexciton-exciton cascade. Our theoretical results are compared with experimental linear absorption and non-linear transient absorption spectra of colloidal GQDs. We next discuss the optical properties of triangular GQDs with zigzag edges whose magnetic moment can be controlled by gates. The control over the magnetic moment through carrier density manipulation results in optical spin blockade and gate tunable optical properties over a wide range of photon energies.
ISSN: 1862-6254
Appears in Collections:Physics / Fizik
Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

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