摘要
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.
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.
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.
