From stripes to hexagons: strain-induced 2D Pb phases confined between graphene and SiC

TL;DR

This study investigates how strain influences the formation of various 2D lead phases intercalated between graphene and SiC, revealing stripe and hexagon patterns through advanced microscopy techniques, advancing understanding of strain-driven 2D material stabilization.

Contribution

It demonstrates the role of strain in stabilizing different 2D Pb phases intercalated beneath graphene, providing new insights into strain-driven phase formation in 2D materials.

Findings

Formation of stripe and hexagon Pb phases due to strain

Strain and substrate pinning influence phase morphology

Graphene enables stabilization of novel 2D metal phases

Abstract

The intercalation of metals beneath graphene offers a powerful route to stabilizing and protecting novel two-dimensional (2D) phases. The epitaxial growth of Pb monolayers on SiC(0001), combined with the relatively large spacing of the suspended graphene, makes this system particularly distinctive. Using low-energy electron diffraction (LEED) and various microscopy techniques -- including scanning electron microscopy (SEM), scanning tunneling microscopy (STM), and low-energy electron microscopy (LEEM) -- we have investigated the intercalation process across multiple length scales. Our analysis reveals the formation of different 2D Pb monolayer phases, such as stripes and hexagons, which emerge due to the interplay between substrate pinning and strain within the Pb layer, depending on local coverage. These findings provide new insights into the strain-driven stabilization of intercalated metal layers and highlight the potential of graphene as a versatile platform for engineering low-dimensional materials.