Thermal conductance of suspended nanoribbons: interplay between strain and interatomic potential nonlinearity

We investigate the role that nonlinearity in the interatomic potential has on the thermal conductance of a suspended nanoribbon when it is subjected to a longitudinal strain. To focus on the first cubic and quartic nonlinear terms of a general potential, we propose an atomic system based on an $\alpha$-$\beta$ Fermi-Pasta-Ulam nearest neighbor interaction. We perform classical molecular dynamics simulations to investigate the contribution of longitudinal, transversal and flexural modes to the thermal conductance as a function of the $\alpha$-$\beta$ parameters and the applied strain. We compare the cases where atoms are allowed to vibrate only {\it in} plane (2D) with the case of vibrations {\it in} and {\it out} of plane (3D). We find that the dependence of conductance on $\alpha$ and $\beta$ relies on a crossover phenomenon between linear/nonlinear delocalized/localized flexural and transversal modes, driven by an on/off switch of the strain.