Diffusion in the random gap model of monolayer and bilayer graphene
Diffusion in the random gap model of monolayer and bilayer graphene
复制标题
单层和双层石墨烯随机间隙模型中的扩散
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
K. Ziegler
中科院分区：
文献类型：
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作者：
K. Ziegler
在本文中，我们研究了单层和双层石墨烯中的波动间隙的影响，由一个破缺的随机势产生。我们确定了一个连续的对称性的两粒子绿色的功能，这是自发破缺的平均两粒子绿色的功能，并导致一个无质量的费米子模式。在一个循环的扩展，它示出的无质量模式占主导地位的小循环在大尺度上。该结果表明电子的扩散。虽然单层和双层石墨烯中的扩散机制是相同的，但后者中的散射量要强得多。中性点处的物理量，如态密度、扩散系数和电导率，由单粒子散射率决定。所有这些量在平均击穿电位的临界值处消失，表明向绝缘行为的连续过渡。
In this paper we study the effect of a fluctuating gap in mono- and bilayer graphene, created by a symmetry-breaking random potential. We identify a continuous symmetry for the two-particle Green’s function which is spontaneously broken in the average two-particle Green’s function and leads to a massless fermion mode. Within a loop expansion it is shown that the massless mode is dominated on large scales by small loops. This result indicates diffusion of electrons. Although the diffusion mechanism is the same in mono- and in bilayer graphene, the amount of scattering is much stronger in the latter. Physical quantities at the neutrality point, such as the density of states, the diffusion coefficient and the conductivity, are determined bythe one-particle scattering rate. All these quantities vanish at a critical value of the average symmetry-breaking potential, signaling a continuous transition to an insulating behavior.