Dynamics of fluctuations and thermal buckling in graphene from a phase-field crystal model

We study the effects of thermal fluctuations and pinned boundaries in graphene membranes by using a phasefield crystal model with out-of-plane deformations. For sufficiently long times, the linear diffusive behavior of height fluctuations in systems with free boundaries becomes a saturation regime, while at intermediate times the behavior is still subdiffusive as observed experimentally. Under compression, we find mirror buckling fluctuations where the average height changes from above to below the pinned boundaries, with the average time between fluctuations diverging below a critical temperature corresponding to a thermally induced buckling transition. Near the transition, we find a nonlinear height response in agreement with recent renormalizationgroup calculations and observed in experiments on graphene membranes under an external transverse force with clamped boundaries.

Automated summary

In this study, the effects of thermal fluctuations and pinned boundaries in graphene membranes are investigated using a phasefield crystal model. The height fluctuations in systems with free boundaries exhibit linear diffusion behavior for long times, but still show subdiffusive behavior at intermediate times, consistent with experimental observations. Under compression, mirror buckling fluctuations are found, where the average height changes from above to below the pinned boundaries, and the average time between fluctuations diverges below a critical temperature corresponding to a thermally induced buckling transition. Near the transition, a nonlinear height response is observed, in agreement with recent renormalization group calculations and experimental results on graphene membranes under an external transverse force with clamped boundaries.