title: Thermolubricity of gas monolayers on graphene.
abstract: Nanofriction of Xe, Kr and N₂ monolayers deposited on graphene was explored with a quartz crystal microbalance (QCM) at temperatures between 25 and 50 K. Graphene was grown by chemical vapour deposition and transferred to the QCM electrodes with a polymer stamp. It was found to strongly adhere to the gold electrodes at temperatures as low as 5 K and at frequencies up to 5 MHz. At low temperatures, the Xe monolayers are fully pinned to the graphene surface. Above 30 K, the Xe film slides and the depinning onset coverage beyond which the film starts sliding decreases with temperature. Similar measurements repeated on bare gold show an enhanced slippage of the Xe films and a decrease of the depinning temperature below 25 K. Nanofriction measurements of Kr and N₂ confirm this scenario. This thermolubric behaviour is explained in terms of a recent theory of the size dependence of static friction between adsorbed islands and crystalline substrates.
authors.affiliation: Dipartimento di Fisica e Astronomia 'G. Galilei' Università di Padova and CNISM, Via Marzolo, 8 35131 Padova, Italy. giampaolo.mistura@unipd.it.
authors.forename: Matteo
authors.initials: M
authors.lastname: Pierno
authors.forename: Luca
authors.initials: L
authors.lastname: Bignardi
authors.forename: Maria Clelia
authors.initials: MC
authors.lastname: Righi
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Bruschi
authors.forename: Stefano
authors.initials: S
authors.lastname: Gottardi
authors.forename: Meike
authors.initials: M
authors.lastname: Stöhr
authors.forename: Oleksii
authors.initials: O
authors.lastname: Ivashenko
authors.forename: Pier Luigi
authors.initials: PL
authors.lastname: Silvestrelli
authors.forename: Petra
authors.initials: P
authors.lastname: Rudolf
authors.forename: Giampaolo
authors.initials: G
authors.lastname: Mistura