Chemical modifications such as intercalation can be used to modify surface properties or to further functionalize the surface states of topological insulators. Using ambient pressure X-ray photoelectron spectroscopy, we report copper migration in CuxBi2Se3, which occurs on a timescale of hours to days after initial surface cleaving. The increase in near-surface copper proceeds along with the oxidation of the sample surface and large changes in the selenium content. These complex changes are further modelled with core-level spectroscopy simulations, which suggest a composition gradient near the surface which develops with oxygen exposure. Our results shed light on a new phenomenon that must be considered for intercalated topological insulators\unicodex2014and intercalated materials in general\unicodex2014that surface chemical composition can change when specimens are exposed to ambient conditions.
@article{arxiv.2207.04155,
title = {Copper migration and surface oxidation of $\text{Cu}_{x}\text{Bi}_2\text{Se}_3$ in ambient pressure environments},
author = {Adam L. Gross and Lorenz Falling and Matthew C. Staab and Metzli I. Montero and Rahim R. Ullah and David M. Nisson and Peter Klavins and Kristie J. Koski and Nicholas J. Curro and Valentin Taufour and Slavomir Nemsak and Inna M. Vishik},
journal= {arXiv preprint arXiv:2207.04155},
year = {2022}
}