Strain in twisted bilayer graphene grown by chemical vapour deposition on Ni surfaces

In this work, we have synthesised twisted bilayer graphene on nickel substrate by chemical vapour deposition. The Moire superlattice generated by a misorientation in the stacking of two layers of graphene was studied. Raman spectroscopy was used to identify regions of interest on the films, in which scanning tunnelling microscopy (STM) was implemented to characterise the system in real space with atomic resolution, while also determining the main features caused by the strain on the bilayer structure. With the aid of simple models, we have probed relevant interrelations between features observed by STM and the heterostrain undergone by the film, which could be seen to suggest extra degrees of freedom in the sense of altering the properties of materials.

Automated summary

Twisted bilayer graphene was synthesized on a nickel substrate using chemical vapour deposition and studied for Moire superlattice generation caused by misorientation in stacking. Raman spectroscopy and scanning tunnelling microscopy (STM) were utilized to identify regions of interest on the films and characterize the system with atomic resolution, revealing main features affected by strain on the bilayer structure. Simple models were used to probe the interrelations between STM-observed features and heterostrain in the film, indicating potential extra degrees of freedom in altering material properties.