The effect of intrinsic crumpling on the mechanics of free-standing graphene.

ABSTRACT: Free-standing graphene is inherently crumpled in the out-of-plane direction due to dynamic flexural phonons and static wrinkling. We explore the consequences of this crumpling on the effective mechanical constants of graphene. We develop a sensitive experimental approach to probe stretching of graphene membranes under low applied stress at cryogenic to room temperatures. We find that the in-plane stiffness of graphene is 20-100?N?m(-1) at room temperature, much smaller than 340?N?m(-1) (the value expected for flat graphene). Moreover, while the in-plane stiffness only increases moderately when the devices are cooled down to 10?K, it approaches 300?N?m(-1) when the aspect ratio of graphene membranes is increased. These results indicate that softening of graphene at temperatures <400?K is caused by static wrinkling, with only a small contribution due to flexural phonons. Together, these results explain the large variation in reported mechanical constants of graphene devices and pave the way towards controlling their mechanical properties.

SUBMITTER: Nicholl RJ 

PROVIDER: S-EPMC4667622 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature