Weak Localization in Graphene Flakes

Abstract

We show that the manifestation of quantum interference in graphene is very different from that in conventional two-dimensional systems. Due to the chiral nature of charge carriers, it is sensitive not only to inelastic, phase-breaking scattering, but also to a number of elastic scattering processes. We study weak localization in different samples and at different carrier densities, including the Dirac region, and find the characteristic rates that determine it. We show how the shape and quality of graphene flakes affect the values of the elastic and inelastic rates and discuss their physical origin.

Electron–Hole Symmetry Breaking in Charge Transport in Nitrogen-Doped Graphene

“…[36][37][38] The chirality of graphene would give rise to the destructive interference of charge carriers in graphene at zero magnetic field. Thus, an increase in the conductivity, namely weak antilocalization (WAL), is expected to occur in monolayer graphene as long as the chiral symmetry is preserved during coherent backscattering.…”

“…47,48 The other is the direct Coulomb interaction ( −1 ) among the charge carriers. 38, 45, 46 By considering both mechanisms, 37, 48 the dephasing rate can be written aswhere g(n)=σh/e 2 . The linear temperature dependent term corresponds to the inelastic scattering with small momentum transfer, while the parabolic temperature dependent term is due to large momentum transfer by the direct Coulomb interaction between charge carriers.…”

Weak localization scattering lengths in epitaxial, and CVD graphene

“…Previous work has typically found similar values for L ϕ of around 0.6 μm. [9][10][11][12] In Ki et al, 11 there has been some previous work carried out on the carrier density dependence by using a single sample with a backgate. In their work they found a superlinear increase of L ϕ with carrier density.…”

“…(1) and these were converted to scattering lengths using, L ϕ,i, * = τ ϕ,i, * D. Figure 3 shows the extracted scattering lengths, from our data and from the literature. [9][10][11][12] Care was taken to extract all values for as close as possible to the same temperature, in this case 1.5 K. This is done since L ϕ in particular is known to vary strongly with temperature. [9][10][11][12] Fits to the data are made using a simple power law, Bn A , the results of which are shown in Table I.…”

“…Devices are analyzed from graphene produced by epitaxial growth on SiC 7 and chemical vapor deposition (CVD) onto thin metal films. 8 The results are compared with those obtained from the literature [9][10][11][12] and together are used to measure trends in the scattering lengths with carrier density.…”