Stoichiometry-driven switching between surface reconstructions on SrTiO$_3$(001)

TL;DR

This study demonstrates how surface stoichiometry controls the reversible switching between different atomic surface reconstructions on SrTiO$_3$(001), revealing the importance of surface composition in oxide surface structures.

Contribution

It provides experimental evidence that surface stoichiometry can reversibly induce different surface reconstructions on SrTiO$_3$(001), highlighting the role of surface composition in atomic-scale control.

Findings

Surface stoichiometry determines surface reconstruction type.

Reversible switching between c(4 × 2) and (2 × 2) reconstructions achieved.

Surface composition confined to the top layer influences geometric models.

Abstract

Controlling the surface structure on the atomic scale is a major difficulty for most transition metal oxides; this is especially true for the ternary perovskites. The influence of surface stoichiometry on the atomic structure of the SrTiO$_3$(001) surface was examined with scanning tunneling microscopy, low-energy electron diffraction, low-energy He$^+$ ion scattering (LEIS), and X-ray photoelectron spectroscopy (XPS). Vapor deposition of 0.8 monolayer (ML) strontium and 0.3 ML titanium, with subsequent annealing to 850 {\deg}C in 4 $\times$ 10$^{-6}$ mbar O$_2$, reversibly switches the surface between c(4 $\times$ 2) and (2 $\times$ 2) reconstructions, respectively. The combination of LEIS and XPS shows a different stoichiometry that is confined to the top layer. Geometric models for these reconstructions need to take into account these different surface compositions.