Intrinsic loss due to unstable modes in graphene

K Kunal and NR Aluru, NANOTECHNOLOGY, 24, 275701 (2013).

DOI: 10.1088/0957-4484/24/27/275701

The mechanism of dissipation operative at the nanoscale remains poorly understood for most cases. In this work, using molecular dynamics simulations, we show that the unstable out-of-plane mode leads to the absorption of energy from the in-plane motion in graphene. The in-plane vibration modulates the potential energy profile for the out-of-plane modes. For the fundamental out-of-plane mode in the loading direction, the minimum of the potential energy shifts because of in-plane compressive strain. The structure takes a finite amount of time to relax to the new potential energy configuration. A hysteresis in the out-of- plane dynamics is observed when the time period of in-plane excitation becomes comparable to the time required for this relaxation. Increasing the stiffness of the out-of-plane modes by giving an initial tensile strain leads to a considerable decrease in dissipation rate.

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