Two-dimensional few-atom noble gas clusters in a graphene sandwich

Abstract

Van der Waals atomic solids of noble gases on metals at cryogenic temperatures were the first experimental examples of two-dimensional systems. Recently such structures have also been created on surfaces under encapsulation by graphene, allowing studies at elevated temperatures through scanning tunneling microscopy. However, for this technique, the encapsulation layer often obscures the actual arrangement of the noble gas atoms. Here, we create Kr and Xe clusters in between two suspended graphene layers, and uncover their atomic structure through direct imaging with transmission electron microscopy. We show that small crystals (N<9) arrange as expected based on the simple non-directional van der Waals interaction. Crystals larger than this show some deviations for the outermost atoms, possibly enabled by deformations in the encapsulating graphene lattice. We further discuss the dynamics of the clusters within the graphene sandwich, and show that while all Xe clusters with up to N~100 remain solid, Kr clusters with already N~16 turn occasionally fluid under our experimental conditions with an estimated pressure of ca. 0.3 GPa. This study opens a way for the so-far unexplored frontier of encapsulated two-dimensional van der Waals solids with exciting possibilities for fundamental condensed matter physics research and possible applications in quantum information technology.

31 pages, 14 figures, including the supplement

References in corpus (5)

• scikit-image: Image processing in Python
• Stone-Wales--type transformations in carbon nanostructures driven by electron irradiation
• Atomic structure and energetics of large vacancies in graphene
• Two-dimensional few-atom noble gas clusters in a graphene sandwich
• Behavior of implanted Xe, Kr and Ar in nanodiamond and thin graphene stacks: experiment and modeling

Cited by in corpus (5)

• Two-dimensional few-atom noble gas clusters in a graphene sandwich
• Bilayer graphene as a template for manufacturing novel 2D materials
• Direct visualization of defect-controlled diffusion in van der Waals gaps
• Characterization of Silicon Carbide Biphenylene Network through G0W0-BSE Calculations
• Mass-transport-limited reaction rates and molecular diffusion in the van der Waals gap beneath graphene