Competing scanning tunneling microscope tip-interlayer interactions for twisted multilayer graphene on the a-plane SiC surface

摘要

Scanning tunneling microscopy (STM) images are obtained for the first time onfew layer and twisted multilayer epitaxial graphene states synthesized on n+6H-SiC a-plane non-polar surface. The twisted graphene is determined to have arotation angle of 5.4{\deg} between the top two layers, by comparing moir\'epatterns from stick and ball models of bilayer graphene to experimentallyobtained images. Furthermore, the experimental moir\'e pattern shows dynamicbehavior, continuously shuffling between two stable surface arrangements onebond length apart. The moir\'e pattern shifts by more than 1 nm, making it easyto observe with STM. Explanation of this dynamic behavior is attributed toelectrostatic interactions between the STM tip and the graphene sample.