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

作　　者：LINing ZHU Wen-Huan LIANG Qi DING Guo-Hui 

机构地区：[1]Instrumental Analysis Center, Shanghai Jiao Tong University, Shanghai 200240 [2]Key Laboratory of Artificial Structures and Quantum Control (Ministry of Bducation),Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240

出　　处：《Chinese Physics Letters》2014年第4期150-154,共5页中国物理快报（英文版）

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.

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.

分 类 号：O53[理学—等离子体物理] O471.1[理学—物理]