Optical conductivity study of screening of many-body effects in graphene interfaces

Abstract

Theoretical studies have shown that electron-electron (e-e) and electron-hole (e-h) interactions play important roles in many observed quantum properties of graphene making this an ideal system to study many body effects. In this report we show that spectroscopic ellipsometry can enable us to measure this interactions quantitatively. We present spectroscopic data in two extreme systems of graphene on quartz (GOQ), an insulator, and graphene on copper (GOC), a metal which show that for GOQ, both e-e and e-h interactions dominate while for GOC e-h interactions are screened. The data further enables the estimation of the strength of the many body interaction through the effective fine structure constant, ${\alpha }_g^{\ast }$. The ${\alpha }_g^{\ast }$ for GOQ indicates a strong correlation with an almost energy independent value of about 1.37. In contrast, ${\alpha }_g^{\ast }$ value of GOC is photon energy dependent, is almost two orders of magnitude lower at low energies indicating very weak correlation.

Main Article (4 pages, 4 figures); Supporting Online Material (12 pages, 9 figures)

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Cited by in corpus (5)

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• Optical conductivity renormalization of graphene on SrTiO${}_3$ due to resonant excitonic effects mediated by Ti 3\textit{d} orbitals
• Self-consistent iteration procedure in analyzing reflectivity and spectroscopic ellipsometry data of multilayered materials and their interfaces
• Symmetry and optical selection rules in graphene quantum dots