A Helium-Surface Interaction Potential of Bi$_2$Te$_3$(111) from Ultrahigh-Resolution Spin-Echo Measurements

TL;DR

This study precisely characterizes the helium-bismuth telluride surface interaction potential using ultrahigh-resolution spin-echo measurements and elastic close-coupling calculations, providing detailed parameters for the potential.

Contribution

It introduces a refined three-dimensional interaction potential for He-Bi$_2$Te$_3$(111) based on experimental data and advanced modeling techniques.

Findings

The potential is described by a corrugated Morse model.

Well depth of the potential is 6.22 meV with small uncertainty.

Surface electronic corrugation is approximately 9.6%."

Abstract

We have determined an atom-surface interaction potential for the He$-$Bi$_2$Te$_3$(111) system by analysing ultrahigh resolution measurements of selective adsorption resonances. The experimental measurements were obtained using $^3$He spin-echo spectrometry. Following an initial free-particle model analysis, we use elastic close-coupling calculations to obtain a three-dimensional potential. The three-dimensional potential is then further refined based on the experimental data set, giving rise to an optimised potential which fully reproduces the experimental data. Based on this analysis, the He$-$Bi$_2$Te$_3$(111) interaction potential can be described by a corrugated Morse potential with a well depth $D=(6.22\pm0.05)~\mathrm{meV}$, a stiffness $\kappa =(0.92\pm0.01)~\mathrm{\AA}^{-1}$ and a surface electronic corrugation of $(9.6\pm0.2)$% of the lattice constant. The improved uncertainties of the atom-surface interaction potential should also enable the use in inelastic close-coupled calculations in order to eventually study the temperature dependence and the line width of selective adsorption resonances.