paper

Stress-controlled Poisson ratio of a crystalline membrane: Application to graphene

arXiv:1801.05476 · doi:10.1103/PhysRevB.97.125402

Abstract

We demonstrate that a key elastic parameter of a suspended crystalline membrane---the Poisson ratio (PR) ---is a non-trivial function of the applied stress and of the system size , i.e., . We consider a generic 2D membrane embedded into space of dimensionality . (The physical situation corresponds to .) A particularly important application of our results is free-standing graphene. We find that at very low stress, where the membrane exhibits a linear response, the PR decreases with increasing and saturates for at a value which depends on the boundary conditions and is essentially different from the value previously predicted by the membrane theory within a self-consisted scaling analysis. By increasing , one drives a membrane into a non-linear regime characterized by a universal value of PR that depends solely on This universal non-linear PR acquires its minimum value in the limit With the further increase of , the PR changes sign and finally saturates at a positive non-universal value prescribed by the conventional elasticity theory. We also show that one should distinguish between the absolute and differential PR ( and , respectively). While coinciding in the limits of very low and very high stresses, they differ in general, . In particular, in the non-linear universal regime, takes a universal value which, similarly to absolute PR, is a function solely of but is different from the universal value of . In the limit , the universal value of tends to , at variance with the limiting value of . Finally, we briefly discuss generalization of these results to a disordered membrane.

21 pages, 9 figures

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