Abstract
Controlling the interlayer coupling in two-dimensional (2D) materials generates novel electronic and topological phases. Its effective implementation is commonly done with a transverse electric field. However, phases generated by high displacement fields are elusive in this standard approach. Here, we introduce an exceptionally large displacement field by structural modification of a model system: AB-stacked bilayer graphene (BLG) on a SiC(0001) surface. We show that upon intercalation of gadolinium, electronic states in the top graphene layers exhibit a significant difference in the on-site potential energy, which effectively breaks the interlayer coupling between them. As a result, for energies close to the corresponding Dirac points, the BLG system behaves like two electronically isolated single graphene layers. This is proven by local scanning tunneling microscopy (STM)/spectroscopy, corroborated by density functional theory, tight binding, and multiprobe STM transport. The work presents metal intercalation as a promising approach for the synthesis of 2D graphene heterostructures with electronic phases generated by giant displacement fields.
| Original language | English |
|---|---|
| Pages (from-to) | 11571-11580 |
| Number of pages | 10 |
| Journal | Journal of Physical Chemistry Letters |
| Volume | 13 |
| Issue number | 49 |
| DOIs | |
| State | Published - Dec 15 2022 |
Funding
This work was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. The research was performed at the Ames Laboratory, which is operated for the U.S. DOE by Iowa State University under Contract DE-AC02-07CH11358. Part of the work (LEED and four-probe STM experiments) was carried out as the user project at the Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, which is a U.S. DOE Office of Science User Facility.