Reversible structure change in graphene/metal interface by intercalation and deintercalation

Intercalation in two-dimensional materials is an important degree of freedom to modify the structural and electronic properties. In this paper, the atomic arrangements at the interface between single-layer graphene and Co(0001) with intercalated Ag and Au atoms were investigated using total-reflection high-energy positron diffraction. A structure analysis on the basis of dynamical diffraction theory demonstrates that by intercalation at annealing temperatures above 400 degrees C, the graphene height from the underlying atoms is shifted from 2.04 angstrom to 3.24 angstrom for Ag and 3.32 angstrom for Au. The Debye temperatures of graphene are changed from 430 K to 320 K for Ag and 368 K for Au by the intercalation. These changes indicate that intercalation results in the transformation to quasifreestanding graphene via a van der Waals interaction. For Ag, further annealing at 700 degrees C enables the graphene height and the Debye temperature to restore the pristine values by Ag deintercalation. However, for Au, the graphene height remains high up to 900 degrees C, which indicates the absence of deintercalation. The obtained results reveal a reversible structure change in the graphene/Co(0001) interface by Ag intercalation and deintercalation. The difference in the deintercalation between Ag and Au atoms can be explained by the activation energy of thermal desorption.

Automated summary

Intercalation of Ag and Au atoms in graphene/Co(0001) interface leads to reversible changes in graphene height and Debye temperature, indicating the importance of intercalation on interface structure.