FisMat2017 - Submission - View

Abstract's title: Pressure Induced Frictional Pinning Transition in Hetero-bilayers : h-BN/MoS2
Submitting author: Yanier Crespo Hernandez
Affiliation: International Centre for Theoretical Physics
Affiliation Address: strada costiera 11, Trieste
Country: Italy
Oral presentation/Poster (Author's request): Poster
Other authors and affiliations: School for Advanced Studies (SISSA), andCNR-IOM Democritos National Simulation Center, Via Bonomea265, I-34136 Trieste, Italy
Abstract
Two monolayer materials such as graphene, h-BN and MoS_$2$ ,
etc., may form hetero-bilayers by physical adhesion, no real
chemistry involved. Mutual incommensurability and weak interlayer
forces would ideally warrant free mutual sliding, unpinned in the
absence of defects. Focusing on the h-BN/MoS2 bilayer, this
"superlubric" state at zero pressure is predicted by accurate first
principles calculations to undergo a first order transition to a
pinned state when squeezed under a pressure of about 1 GPa, in
full electron and lattice equilibrium. There is no chemical rebonding
at the transition, but there is a first order change of interlayer
distance and of in-plane cell size accompanied by a jump of h-BN
out-of-plane corrugation. The accompanying jump of Coppersmith-
Fisher's "disorder parameter" qualifies this as a 2D Aubry-type
transition, of which there are no known examples, marking the
onset of strong interlayer friction.The bilayer is also expected to
exhibit thermal and electrical contact properties quite different from
the zero pressure unpinned state. This first order pinning transition
may also be expected to end with a critical point at a finite.
temperatureses.