STM Study of Draped and Wrinkled Graphene

Understanding the mechanical properties of materials is one of the oldest branches of physics. After studying bulk materials for centuries, with the discovery of graphene, it was soon realized that strained 2D materials would deform significantly more than their bulk counterparts. Furthermore, the demonstration of Landau Levels in strained graphene opened up the field of manipulating electronic states by exploiting its mechanical properties. Despite initial ebullience, the field of strained 2D materials still lingers in its infancy as engineering strain and studying mechanical properties at the nanoscale remains a challenge.

Here we present results from STM investigations of graphene strained by two methods: draped over large (up to ~35nm) Cu step edges, and wrinkled by differential thermal contraction between the graphene and the Cu substrate. Our results provide insights into understanding the mechanical properties of 2D films required to directly strain engineer these systems.