Two-Dimensional Molecular Charge Density Waves in Single-Layer-Thick Islands of a Dirac Fermion System

Kyaw Zin Latt, John A. Schlueter, Pierre Darancet, Saw Wai Hla*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Charge density waves have been intensely studied in inorganic materials such as transition metal dichalcogenides; however their counterpart in organic materials has yet to be explored in detail. Here we report the finding of robust two-dimensional charge density waves in molecular layers formed by α-(BEDT-TTF)2-I3 on a Ag(111) surface. Low-temperature scanning tunneling microscopy images of a multilayer thick α-(BEDT-TTF)2-I3 on a Ag(111) substrate reveal the coexistence of 5a0 × 5a0 and 31a0×31a0 R9° charge density wave patterns commensurate with the underlying molecular lattice at 80 K. Both charge density wave patterns remain in nanosize molecular islands with just a single constituent molecular-layer thickness at 80 and 5 K. Local tunneling spectroscopy measurements reveal the variation of the gap from 244 to 288 meV between the maximum and minimum charge density wave locations. Density functional theory calculations further confirm a vertical positioning of BEDT-TTF molecules in the molecular layer. While the observed charge density wave patterns are stable for the defect sites, they can be reversibly switched for one molecular lattice site by means of inelastic tunneling electron energy transfer with the electron energies exceeding 400 meV using a scanning tunneling microscope manipulation scheme.

Original languageEnglish (US)
Pages (from-to)8887-8893
Number of pages7
JournalACS nano
Volume14
Issue number7
DOIs
StatePublished - Jul 28 2020

Keywords

  • Ag(111) surface
  • charge density wave
  • inelastic electron tunneling
  • molecular Dirac fermion system
  • molecule manipulation
  • scanning tunneling microscopy
  • tunneling spectroscopy

ASJC Scopus subject areas

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy

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