Tuning the effective fine structure constant in graphene: opposing effects of dielectric screening on short- and long-range potential scattering |
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Authors: | Jang C Adam S Chen J-H Williams E D Das Sarma S Fuhrer M S |
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Institution: | Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742-4111, USA. |
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Abstract: | We reduce the dimensionless interaction strength alpha 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. |
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