| AVS 60th International Symposium and Exhibition | |
| Graphene and Other 2D Materials Focus Topic | Wednesday Sessions |
| Session GR+AS+EM+NS+SS-WeA |
| Session: | Dopants, Defects and Interfaces in 2D Materials |
| Presenter: | M.F. Crommie, University of California, Berkeley |
| Authors: | M.F. Crommie, University of California, Berkeley Y. Wang, University of California, Berkeley D. Wong, University of California, Berkeley V.W. Brar, California Institute of Technology H.-Z. Tsai, University of California, Berkeley S. Choi, University of California, Berkeley W. Regan, University of California, Berkeley R. Kawakami, University of California, Riverside A.V. Shytov, University of Exeter, UK A. Zettl, University of California, Berkeley S.G. Louie, University of California, Berkeley L.S. Levitov, Massachusetts Institute of Technology |
| Correspondent: | Click to Email |
Graphene has unique electronic properties that arise from its 2D honeycomb structure and which cause novel behavior at the atomic scale. This can be seen in graphene’s response to charged impurities, where graphene’s ultra-relativistic nature leads to impurity states that are unlike those found in any other material. The physics of Coulomb impurities on graphene is divided into two regimes: subcritical and supercritical. In the subcritical regime no bound states form around the impurity. When the impurity charge exceeds the threshold for supercritical behavior, however, “atomic collapse” states are predicted to emerge. Such states are different from semiconductor impurity states in that their wave functions are composed of a near-field collapsing electron-like component that is coupled via Klein tunneling to a far-field hole-like component that escapes to infinity. We have explored such impurity states across different impurity-charge regimes by building charge centers (i.e., “artificial nuclei”) atom-by-atom at the surface of graphene devices and probing them via scanning tunneling microscopy. New results on this topic, including the observation of “atomic collapse” [1], will be discussed.
References:
[1] Y. Wang, D. Wong, A. V. Shytov, V. W. Brar, S. Choi, Q. Wu, H.-Z. Tsai, W. Regan, A. Zettl, R. K. Kawakami, S. G. Louie, L. S. Levitov, M. F. Crommie, “ Observing Atomic Collapse Resonances in Artificial Nuclei on Graphene“, Science, DOI:10.1126, March 7, 2013.