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. ...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.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 91121021 and 11074166, and Shanghai Natural Science Foundation under Grant No 12ZR1413300.
文摘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.
