title: 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.
authors.affiliation: Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
authors.forename: Ryan J T
authors.initials: RJ
authors.lastname: Nicholl
authors.affiliation: Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
authors.forename: Hiram J
authors.initials: HJ
authors.lastname: Conley
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Nickolay V
authors.initials: NV
authors.lastname: Lavrik
authors.affiliation: Energy &Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Ivan
authors.initials: I
authors.lastname: Vlassiouk
authors.affiliation: Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
authors.forename: Yevgeniy S
authors.initials: YS
authors.lastname: Puzyrev
authors.affiliation: Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
authors.forename: Vijayashree Parsi
authors.initials: VP
authors.lastname: Sreenivas
authors.affiliation: Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
authors.forename: Sokrates T
authors.identifier: http://orcid.org/0000-0002-2963-7545
authors.initials: ST
authors.lastname: Pantelides
authors.affiliation: Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.|Department of Physics, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany.
authors.forename: Kirill I
authors.initials: KI
authors.lastname: Bolotin