| CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES |
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The Edge Magnetization and Strip Phase of Graphene Quantum Dots with Long-Range Coulomb Interaction |
| LI Ning1, ZHU Wen-Huan2, LIANG Qi1, DING Guo-Hui2** |
1Instrumental Analysis Center, Shanghai Jiao Tong University, Shanghai 200240
2Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240
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| Cite this article: |
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LI Ning, ZHU Wen-Huan, LIANG Qi et al 2014 Chin. Phys. Lett. 31 047303 |
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Abstract We investigate the magnetism and optical absorption properties of charge neutral hexagonal graphene quantum dots (GQDs) terminated with zigzag edges by using a tight-binding Hubbard type model for the π electrons. Within the Hartree–Fock approximation and taking into account the long-range Coulomb interaction, our calculation yields a ferromagnetic ground state with magnetic moments localized on the edges for GQDs, and also gives an antiferromagnetism state with the energy very close to the ferromagnetism ground state. We find that both the ferromagnetic and the antiferromagnetic 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.
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Received: 06 December 2013
Published: 25 March 2014
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| PACS: |
73.21.-b
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(Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems)
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73.20.At
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(Surface states, band structure, electron density of states)
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78.40.-q
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(Absorption and reflection spectra: visible and ultraviolet)
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