Anharmonic phonons in Graphene

S. COSTAMAGNA; K. H. MICHEL; F. M. PEETERS

Amberes

Workshop; Nanostructured Graphene; 2013

University of Antwerp

We have obtained the temperature dependence of acoustical phonon life-times and band-shift of graphene. We calculated also its dependence with the wave-vector q and identified normal and umklapp contributions. The later are important since they are responsible for the large thermal conductivity of graphene. We have extended the calculation to include 4th order corrections which are important for the band-shift because they compensate the negative shift due to 3rd order ones and provide stability to the material. The most strong effects are produced in the flexural phonon band (out-of-plane displacements) and in the limit of long wave-lenghts (q → 0) where this band behaves quadratic against q (w ~ q^2).