Wang Lin, Wang Yang, Chen Xiaolong, Zhu Wei, Zhu Chao, Wu Zefei, Han Yu, Zhang Mingwei, Li Wei, He Yuheng, Xiong Wei, Law Kam Tuen, Su Dangsheng, Wang Ning
Department of Physics and the William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Hong Kong, China.
Sci Rep. 2013;3:2041. doi: 10.1038/srep02041.
We demonstrate that single-layer graphene (SLG) decorated with a high density of Ag adatoms displays the unconventional phenomenon of negative quantum capacitance. The Ag adatoms act as resonant impurities and form nearly dispersionless resonant impurity bands near the charge neutrality point (CNP). Resonant impurities quench the kinetic energy and drive the electrons to the Coulomb energy dominated regime with negative compressibility. In the absence of a magnetic field, negative quantum capacitance is observed near the CNP. In the quantum Hall regime, negative quantum capacitance behavior at several Landau level positions is displayed, which is associated with the quenching of kinetic energy by the formation of Landau levels. The negative quantum capacitance effect near the CNP is further enhanced in the presence of Landau levels due to the magnetic-field-enhanced Coulomb interactions.
我们证明，装饰有高密度银吸附原子的单层石墨烯（SLG）表现出负量子电容这一非常规现象。银吸附原子充当共振杂质，并在电荷中性点（CNP）附近形成几乎无色散的共振杂质带。共振杂质抑制动能并将电子驱动到具有负压缩性的库仑能主导区域。在没有磁场的情况下，在CNP附近观察到负量子电容。在量子霍尔 regime 中，在几个朗道能级位置显示出负量子电容行为，这与通过形成朗道能级抑制动能有关。由于磁场增强的库仑相互作用，在存在朗道能级的情况下，CNP附近的负量子电容效应进一步增强。
