Vibration-assisted tunneling through single Au adatoms on two-dimensional WSe2

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Main Authors: Kumar, Hitesh, Lin, Yu-Chuan, Robinson, Joshua A., Fölsch, Stefan
Format: Preprint
Published: 2025
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author Kumar, Hitesh
Lin, Yu-Chuan
Robinson, Joshua A.
Fölsch, Stefan
author_facet Kumar, Hitesh
Lin, Yu-Chuan
Robinson, Joshua A.
Fölsch, Stefan
contents Scanning tunneling microscopy (STM) at 5 K was used to study individual Au atoms adsorbed on the surface of a WSe2 layer grown on epitaxial graphene. In line with theoretical predictions, scanning tunneling spectroscopy measurements reveal that the weakly bound adatom gives rise to an electronic state within the energy band gap of the WSe2 layer. Adatoms in different surface locations show different gap-state energy values that follow a random distribution around the Fermi level of the sample with a standard deviation of ~50 meV. The location-dependent shift is attributed to spatial variations in disorder potential. Tunneling via the gap state is accompanied by vibrational excitations as apparent from pronounced sideband peaks in the conductance spectra with Poisson-distributed intensities indicating significant electron-phonon coupling with a Huang-Rhys factor of S=2.8. STM tunneling through single Au adatoms on two-dimensional WSe2 constitutes a model case of resonant double-barrier tunneling accompanied by strong coupling to vibrational degrees of freedom.
format Preprint
id arxiv_https___arxiv_org_abs_2504_12055
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Vibration-assisted tunneling through single Au adatoms on two-dimensional WSe2
Kumar, Hitesh
Lin, Yu-Chuan
Robinson, Joshua A.
Fölsch, Stefan
Mesoscale and Nanoscale Physics
Scanning tunneling microscopy (STM) at 5 K was used to study individual Au atoms adsorbed on the surface of a WSe2 layer grown on epitaxial graphene. In line with theoretical predictions, scanning tunneling spectroscopy measurements reveal that the weakly bound adatom gives rise to an electronic state within the energy band gap of the WSe2 layer. Adatoms in different surface locations show different gap-state energy values that follow a random distribution around the Fermi level of the sample with a standard deviation of ~50 meV. The location-dependent shift is attributed to spatial variations in disorder potential. Tunneling via the gap state is accompanied by vibrational excitations as apparent from pronounced sideband peaks in the conductance spectra with Poisson-distributed intensities indicating significant electron-phonon coupling with a Huang-Rhys factor of S=2.8. STM tunneling through single Au adatoms on two-dimensional WSe2 constitutes a model case of resonant double-barrier tunneling accompanied by strong coupling to vibrational degrees of freedom.
title Vibration-assisted tunneling through single Au adatoms on two-dimensional WSe2
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2504.12055