Tuning the Effective Fine Structure Constant in Graphene: Opposing Effects of Dielectric Screening on Short- and Long-Range Potential Scattering

C. Jang, S. Adam, J.-H. Chen, E. D. Williams, S. Das Sarma, and M. S. Fuhrer

Phys. Rev. Lett. 101, 146805 – Published 3 October 2008

Abstract

We reduce the dimensionless interaction strength $α$ in graphene by adding a water overlayer in ultrahigh vacuum, thereby increasing dielectric screening. The mobility limited by long-range impurity scattering is increased over 30%, due to the background dielectric constant enhancement leading to a reduced interaction of electrons with charged impurities. However, the carrier-density-independent conductivity due to short-range impurities is decreased by almost 40%, due to reduced screening of the impurity potential by conduction electrons. The minimum conductivity is nearly unchanged, due to canceling contributions from the electron-hole puddle density and long-range impurity mobility. Experimental data are compared with theoretical predictions with excellent agreement.

Received 26 May 2008

DOI:https://doi.org/10.1103/PhysRevLett.101.146805

Authors & Affiliations

C. Jang¹, S. Adam², J.-H. Chen^1,3, E. D. Williams^1,3, S. Das Sarma^1,2, and M. S. Fuhrer^1,3

¹Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742-4111, USA
²Condensed Matter Theory Center, University of Maryland, College Park, Maryland 20742-4111, USA
³Materials Research Science and Engineering Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA

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Vol. 101, Iss. 14 — 3 October 2008

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