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 a '1 at room temperature, much smaller than 340 N m a '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 a '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.
| Original language | English |
|---|---|
| Article number | 8789 |
| Journal | Nature Communications |
| Volume | 6 |
| DOIs | |
| State | Published - Nov 6 2015 |
Funding
We acknowledge enlightening conversations with Paul McEuen, Isaac Storch and Caglar Oskay as well as financial support from NSF CAREER 4-20-632-3391, Defense Threat Reduction Agency Basic Research Award # HDTRA1-15-1-0036 and the Sloan Foundation. A part of this research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the US Department of Energy under Contract No. DE-FG02-09ER46554 as well as resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the US Department of Energy under Contract No. DE-AC05-00OR22725.