Coulomb blockade in graphene nanodisks
Coulomb blockade in graphene nanodisks
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DOI：
10.1103/physrevb.77.155411
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发表时间：
2008-04-01
影响因子：
3.7
通讯作者：
Ezawa, Motohiko
中科院分区：
文献类型：
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作者：
Ezawa, Motohiko
石墨烯纳米盘是一种具有闭合边的石墨烯衍生物。尺寸为N的三角形之字形纳米盘包含一个具有SU(N)对称性的零能扇区。我们研究了零能区内的电子-电子相互作用效应。我们显式地导出了直接相互作用和交换相互作用，它们显式地打破了SU(N)对称性。然后，通过将纳米盘看作具有内部自由度的量子点，我们分析了由一个纳米盘和两个引线组成的纳米盘-引线系统。利用标准格林函数方法，我们揭示了该系统中的库仑阻塞效应。随着化学势的增加，占据数中出现了一系列特殊的平台和凹陷，电导中出现了一系列特殊的库仑阻塞峰，它们反映了破坏SU(N)对称性的纳米盘的能谱。结果表明，由于库仑关联效应，占位数出现了下降，而由于纳米盘和引线之间的隧道效应，出现了微小的库仑阻塞峰。
Graphene nanodisk is a graphene derivative with a closed edge. The trigonal zigzag nanodisk with size N contains a zero-energy sector with the SU(N) symmetry. We investigate electron-electron interaction effects within the zero-energy sector. We explicitly derive the direct and exchange interactions, which explicitly break the SU(N) symmetry. Then, by regarding a nanodisk as a quantum dot with an internal degree of freedom, we analyze the nanodisk-lead system consisting of a nanodisk and two leads. By employing the standard Green's function method, we reveal Coulomb blockade effects in this system. As the chemical potential increases, a peculiar series of plateaux and dips develops in the occupation number and a peculiar series of Coulomb blockade peaks develops in the conductance, which reflect the energy spectrum of a nanodisk with a broken SU(N) symmetry. It is argued that dips emerge in the occupation number due to a Coulomb correlation effect and that tiny Coulomb blockade peaks emerge due to a tunneling effect between the nanodisk and leads.