[Zurück]

I. Sokolovic, G. Franceschi, Z. Wang, J. Xu, J. Pavelec, M. Riva, M. Schmid, U. Diebold, M. Setvin:
"Thermal (in)stability of the bulk-terminated SrTiO₃(001) surface";
Poster: DPG-Frühjahrstagung (DPG Spring Meeting) of the Surface Science Division, SurfaceScience21, virtual; 03.03.2021.

The assumption of bulk-terminated perovskite oxide surfaces is common in most studies in literature, mostly based on (1×1) diffraction patterns observed in LEED or RHEED. The same is true for the prototypical SrTiO3(001) perovskite surface, but the only direct evidence of an unreconstructed SrTiO3(001) surface comes from our previous study [1], where it was obtained by cleaving single crystals, and studying the atomically flat surfaces with ncAFM. These surfaces consist of both (1×1)-terminated SrO and TiO2 terminations, each covered with intrinsic polarity-compensating point defects. Neither of these two terminations is stable upon heating to 500 ∘C in UHV as clearly shown by ncAFM, despite the (1×1) LEED pattern and no shifts in XPS [2]. The (1×1) termination was also not observed by ncAFM on TiO2-terminated surfaces prepared by traditional wet-chemistry, which likewise exhibit the (1×1) LEED pattern [2]. These clear evidence that the (1×1) LEED diffraction patterns can originate from subsurface layers below a disordered surface should be taken into account, since the common assumption of a pristine and unreconstructed SrTiO3(001) might not be warranted. [1] Sokolović et al., Phys. Rev. Mater. 3, 034407 (2019), [2] Sokolović et al., arXiv:2012.08831 (2020).