The Edge Magnetization and Strip Phase of Graphene Quantum Dots with Long-Range Coulomb Interaction

We investigate the magnetism and optical absorption properties of charge neutral hexagonal graphene quantum dots (GODs) terminated with zigzag edges by using a tight-binding Hubbard type model for the 7r electrons. Within the Hartree Fock approximation and taking into account the long-range Coulomb...

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Veröffentlicht in:Chinese physics letters 2014-04, Vol.31 (4), p.150-154
Hauptverfasser: Li, Ning, Zhu, Wen-Huan, Liang, Qi, Ding, Guo-Hui
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Sprache:eng
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Zusammenfassung:We investigate the magnetism and optical absorption properties of charge neutral hexagonal graphene quantum dots (GODs) terminated with zigzag edges by using a tight-binding Hubbard type model for the 7r electrons. Within the Hartree Fock approximation and taking into account the long-range Coulomb interaction, our cal- culation yields a ferromagnetic ground state with magnetic moments localized on the edges for GODs, and also gives an antiferromagnetism state with the energy very c/ose to the ferromagnetism ground state. We find that both the ferromagnetic and the antiferrornagnetic states have stripe patterned charge density distributions as a result of the long-range Coulomb interaction. The optical conductivity for GQDs has an energy gap in the low frequency regime in contrast to the bulk neutral graphene sheet where a universal constant is approached.
ISSN:0256-307X
1741-3540
DOI:10.1088/0256-307X/31/4/047303