题　目：Magnetic adatoms on graphene out and in the Kondo regime: an Anderson model treatment
报告人：朱振刚教授（中国科学院大学 电子电气与通信工程学院）
时　间：7月11日（周四），上午9:30
地　点：南校区第一实验楼406会议室

摘要：

Employing a partial-wave representation we study the nature of the coupling between the impurity and the conducting electrons for two configurations: the adatom is above one carbon atom (ADA) and above the center of the honeycomb (ADC). For ADA the impurity is coupled with one flavor for both A and B sublattice and both Dirac cones. For ADC the impurity couples with multi-flavor states for a spinor state of the impurity. We show, explicitly for a 3d magnetic atom, d_z²，（d_xz, d_yz）and (d_x²_-y²，d_xy) couple respectively with the Γ₁, Γ₅ (E₁) and Γ₆ (E₂) representations of C_6v group in ADC case. We further study the ADA case in terms of slave-boson method and introduce a topological picture to analyze the phase shift and the occupation on the impurity. In order to investigate Kondo effect in this material in this case, we calculate the higher-order correction to the Green’s function. It is found that the Kondo resonance occurs in a narrow energy range of the impurity level around the Fermi energy, which can be tuned by a gate voltage. We show that this range is linear in the Fermi energy |μ| and is significantly narrower than in the case of a normal metal. The singularity in the full Green’s function is also analyzed with the help of a transparent geometrical method. The relations between the various self-energies and the implications for the experimental observations are discussed.

个人简介：

2013年被聘为中国科学院大学，电子电气与通信工程学院教授、博导。2003年获得中国科学院研究生院理学博士；2003-2005年,在清华大学高等研究中心从事博士后研究；2005-2007年以Research Fellow身份工作于新加坡国立大学硅纳米器件实验室；2007-2012年以Research Associate身份在德国马丁路德大学工作。目前已发表SCI文章30多篇，引用约300次。长期担任ACS Nano，Phys. Rev. Lett., Phys. Rev. B, Carbon, Solid State Communications, 和Mod. Phys. Lett. B等杂志的审稿人。主要研究领域有凝聚态材料中关联和拓扑效应，半导体自旋电子学理论和器件、非平衡量子输运等。