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Prof. Enrique Munoz

Pontificia Universidad Catolica de Chile, Santiago

Phonon-limited transport coefficients in extrinsic graphene

Anfang
05.08.2013 14:00 Uhr
Veranstaltungsort
room N-270, Bld. 04.8

Graphene, a two-dimensional honeycomb lattice of carbon atoms, exhibits remarkable electronic, mechanical and thermal properties [1]. Conduction electrons in this material behave as relativistic massless chiral spinors, which can interact with the quantized mechanical vibrations (phonons) even at low temperatures. In this talk, the effect of electron-phonon scattering processes over the transport properties of extrinsic graphene will be discussed[2].
Electron-phonon interaction will be first formulated in second quantization, for chiral Dirac spinors and phonon Bose fields, within the deformation potential approximation.
Electrical and thermal resistivity, as well as the thermopower, are obtained within the Bloch theory approximations. Analytical expressions for the different transport coefficients, calculated from a variational solution of the Boltzmann transport equation, will be presented and discussed. The analytical expressions obtained from the theory predict a linear in temperature dependence of the electrical resistivity at high temperatures, but an unusual ~T^4 dependence at low temperature, in agreement with experiments[3]. The phonon-limited thermal resistivity exhibits a ~ T dependence and achieves a nearly constant value at high temperatures. The predicted Seebeck coefficient exhibits a n^{-1/2} dependence on the extrinsic carrier density, also in agreement with experiments in the literature[4].

[1] E. Munoz, J. Lu and B. I. Yakobson, Nano Letters 10 (2010) 1652.

[2] E. Munoz, Journal of Physics: Condensed Matter 24 (2012) 195302.

[3] Efetov, D. and Kim., P, Physical Review Letters 105 (2010) 256805.

[4] Wei, P. et al., Physical Review Letters 102 (2009) 166808.

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