Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 39: Computational Materials Modelling - Transport, Excitations, Time Dependence I

MM 39.1: Vortrag

Mittwoch, 13. März 2013, 15:00–15:15, H24

Thermal conductivity of graphene from first principles — •Andrea Cepellotti¹, Nicola Bonini², and Nicola Marzari¹ — ¹Theory and Simulation of Materials, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland — ²Department of Physics, King’s College London, London WC2R 2LS, United Kingdom

The thermal conductivity of graphene is computed from the Boltzmann equation for phonon transport, where phonons are treated semiclassically and vibrational properties and anharmonic scattering rates are obtained from density-functional perturbation theory. We show that the commonly used single-mode relaxation time approximation (SMRTA) is not accurate, even at high temperatures, due to the unusually large number of normal scattering processes compared to umklapp ones. By relaxing the SMRTA and solving the Boltzmann equation self-consistently [1] we are able to recover excellent agreement with experimental data [2]. We also rationalize the variations in experimental measurements as an effect of sample finite dimensions, due to the large contributions coming from long wavelength phonons. As pointed out in previous simulations [3], we underline the critical role of strain in the renormalization of the out-of-plane acoustic modes and quantify its effects. Finally, we show how strain and sample size can be used to tune thermal conductivity in graphene over a large range of values.

[1] M. Omini and A. Sparavigna, Nuovo Cimento D 19, 1537 (1997).

[2] A. A. Balandin, Nat. Mater. 10, 569 (2011).

[3] N. Bonini, J. Garg and N. Marzari, Nano Lett. 12, 2673 (2012).