Bound states of charges on top of graphene in a magnetic field
Bound states of charges on top of graphene in a magnetic field
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DOI：
10.1103/physrevb.92.195426
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发表时间：
2015-05
影响因子：
3.7
通讯作者：
S. Slizovskiy
中科院分区：
文献类型：
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作者：
S. Slizovskiy
我们从理论上证明，在外部磁场中，石墨烯单层顶部的类电荷可以相互吸引形成大分子。为了实现这一点，石墨烯需要处于量子霍尔高原状态，局部化学势介于朗道能级之间。石墨烯电子被定位在电荷之间的中间，并提供电荷之间的库仑排斥的过度筛选。所得到的大分子的大小是磁长度的数量级（磁场10t为$\sim 10$ nm）。对磁场作用下石墨烯上单位电荷可能形成的稳定大分子进行了分类。这种结合能在显著的温度下存活，超过许多离子键杂质的迁移障碍。讨论了山谷混合可能产生的晶格尺度效应的影响。调节石墨烯的掺杂或磁场，可以打开和关闭杂质的结合，并可以调节大分子的大小。这为利用磁场和门控对石墨烯上的离子进行纳米级操纵开辟了前景。
We show theoretically that in the external magnetic field like charges on top of graphene monolayer may be mutually attracted to form macro-molecules. For this to happen graphene needs to be in Quantum Hall plateau state with local chemical potential being between the Landau levels. Graphene electron(s) gets localized in the middle between charges and provides overscreening of Coulomb repulsion between the charges. The size of the resulting macro-molecules is of the order of the magnetic length ($\sim 10$ nm for magnetic field 10 T). The possible stable macro-molecules that unit charges can form on graphene in magnetic field are classified. The binding survives significant temperatures, exceeding mobility barriers for many ionically bond impurities. The influence of possible lattice-scale effects of valley-mixing are discussed. Tuning the doping of graphene or the magnetic field, the binding of impurities can be turned on and off and the macro-molecule size may be tuned. This opens the perspective to nanoscopic manipulation of ions on graphene by using magnetic field and gating.