ATOMIC VACANCIES AND BOUNDARY CONDITIONS ON THE BALLISTIC THERMAL TRANSPORT IN GRAPHENE NANORIBBONS

PABLO SCURACCHIO; SEBASTIÁN COSTAMAGNA; ARIEL DOBRY

Bueno Aires

Conferencia; 27 International Conference on Low Temperature Physics; 2014

Universidad de Buenos Aires e Instituto de Física de Bs As

We study the quantum thermal transport in graphene nanoribbons under the presence of single atomic vacancies and subjected to different edges-conditions. We start with a full comparison of the phonon polarizations and energy dispersions given by a Fifth Nearest Neighbor Force Constant Model [1] and the elasticity theory of continuum membranes. Then, by means of the Non Equilibrium Green's Function technique we obtain results for the ballistic thermal conductance and identify the contribution of every single phonon mode at low energy [2]. While edge and central located single atomic vacancies do not affect the transmission function of in-plane phonon modes, they reduce considerably the contributions from flexural modes. We found that boundary conditions have also strong impact on the thermal transport properties. Different to what occurs in free-standing, clamped ribbons have a sample size dependent energy gap in the phonon spectrum. These findings could open a route to design graphene based devices where it is possible to discriminate the contribution of polarized phonons and govern thus the thermal transport on the nanoscale. [1]K. H. Michel & B. Verberck, Phys. Rev B 78, 085424 - 2008.[2]Z. Huang, T. S. Fisher, & J. Y. Murthy, Journal of Applied Physics 108, 094319 - 2010.