Jump to main content
Jump to site search
Access to RSC content Close the message box

Continue to access RSC content when you are not at your institution. Follow our step-by-step guide.


Issue 25, 2017
Previous Article Next Article

Graphene on h-BN: to align or not to align?

Author affiliations

Abstract

The contact strength, adhesion and friction, between graphene and an incommensurate crystalline substrate such as h-BN depends on their relative alignment angle θ. The well-established Novaco–McTague (NM) theory predicts for a monolayer graphene on a hard bulk h-BN crystal face a small spontaneous misalignment, here θNM ≃ 0.45 degrees which if realized would be relevant to a host of electronic properties besides the mechanical ones. Because experimental equilibrium is hard to achieve, we inquire theoretically about alignment or misalignment by simulations based on dependable state-of-the-art interatomic force fields. Surprisingly at first, we find compelling evidence for θ = 0, i.e., full energy-driven alignment in the equilibrium state of graphene on h-BN. Two factors drive this deviation from the NM theory. First, graphene is not flat, developing on h-BN a long-wavelength out-of-plane corrugation. Second, h-BN is not hard, releasing its contact stress by planar contractions/expansions that accompany the interface moiré structure. Repeated simulations by artificially forcing graphene to keep flat, and h-BN to keep rigid, indeed yield an equilibrium misalignment similar to θNM as expected. Subsequent sliding simulations show that friction of graphene on h-BN, small and essentially independent of misalignments in the artificial frozen state, strongly increases in the more realistic corrugated, strain-modulated, aligned state.

Graphical abstract: Graphene on h-BN: to align or not to align?

Back to tab navigation

Article information


Submitted
03 Apr 2017
Accepted
19 May 2017
First published
24 May 2017

Nanoscale, 2017,9, 8799-8804
Article type
Paper

Graphene on h-BN: to align or not to align?

R. Guerra, M. van Wijk, A. Vanossi, A. Fasolino and E. Tosatti, Nanoscale, 2017, 9, 8799
DOI: 10.1039/C7NR02352A

Social activity

Search articles by author

Spotlight

Advertisements