Scanning tunneling spectroscopy of a magnetic atom on graphene in the Kondo regimeHuai-Bin Zhuang1, Qing-feng Sun1 and X. C. Xie1, 2
1 Beijing National Lab for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences Beijing 100190, China
2 Department of Physics, Oklahoma State University - Stillwater, OK 74078, USA
received 11 March 2009; accepted in final form 25 May 2009; published June 2009
published online 23 June 2009
The Kondo effect in the system consisting of a magnetic adatom on the graphene is studied. By using the non-equilibrium Green function method with the slave-boson mean-field approximation, the local density of state (LDOS) and the conductance are calculated. For a doped graphene, the Kondo phase is present at all time. Surprisingly, two kinds of Kondo regimes are revealed. But for the undoped graphene, the Kondo phase only exists if the adatom's energy level is beyond a critical value. The conductance is similar to the LDOS, thus, the Kondo peak in the LDOS can be observed with the scanning tunneling spectroscopy. In addition, in the presence of a direct coupling between the STM tip and the graphene, the conductance may be dramatically enhanced, depending on the coupling site.
81.05.Uw - Carbon, diamond, graphite.
72.15.Qm - Scattering mechanisms and Kondo effect.
© EPLA 2009