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arXiv 1107.4741cond-mat.str-elcond-mat.stat-mechmath-phmath.MP
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石墨烯的晶格量子电动力学

Lattice quantum electrodynamics for graphene

Alessandro Giuliani, Vieri Mastropietro, Marcello Porta

摘要:

到目前为止,石墨烯中规范相互作用的影响已经根据狄拉克费米子的有效模型进行了分析。然而,在某些情况下,晶格效应起着重要的作用,需要始终考虑。介绍并分析了石墨烯的格点规范理论模型,该模型描述了紧束缚电子在蜂窝晶格上的跳跃以及与三维量子U(1)规范场的相互作用.我们执行一个精确的重整化群分析,这导致一个重整化展开,在所有的订单是有限的。由于沃德恒等式和对模型的离散晶格对称性的仔细分析,有效参数的流动得到控制。我们表明,费米速度增加到光速和洛伦兹不变性自发出现在红外。相互作用在响应函数中产生临界指数;这消除了非相互作用情况下存在的简并性,并使我们能够识别主导激发。最后,我们添加质量项的哈密顿量,并推导出相应的间隙方程,其中有一个异常的非BCS形式,由于非平凡的相互作用的影响。

英文摘要:

The effects of gauge interactions in graphene have been analyzed up to now in terms of effective models of Dirac fermions. However, in several cases lattice effects play an important role and need to be taken consistently into account. In this paper we introduce and analyze a lattice gauge theory model for graphene, which describes tight binding electrons hopping on the honeycomb lattice and interacting with a three-dimensional quantum U(1) gauge field. We perform an exact Renormalization Group analysis, which leads to a renormalized expansion that is finite at all orders. The flow of the effective parameters is controlled thanks to Ward Identities and a careful analysis of the discrete lattice symmetry properties of the model. We show that the Fermi velocity increases up to the speed of light and Lorentz invariance spontaneously emerges in the infrared. The interaction produces critical exponents in the response functions; this removes the degeneracy present in the non interacting case and allow us to identify the dominant excitations. Finally we add mass terms to the Hamiltonian and derive by a variational argument the correspondent gap equations, which have an anomalous non-BCS form, due to the non trivial effects of the interaction.

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