Quest for a pristine unreconstructed <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>SrTiO</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mrow><mml:mo>(</mml:mo><mml:mn>001</mml:mn><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math> surface: An atomically resolved study via noncontact atomic force microscopy
Igor Sokolović, Giada Franceschi, Zhichang Wang, Jian Xu, Jiří Pavelec, Michele Riva, Michael Schmid, Ulrike Diebold, Martin Setvín
Abstract
The surfaces of perovskite oxides affect their functional properties, and while a bulk-truncated $(1\ifmmode\times\else\texttimes\fi{}1)$ termination is generally assumed, its existence and stability is controversial. Here, such a surface is created by cleaving the prototypical ${\mathrm{SrTiO}}_{3}$(001) in ultrahigh vacuum, and its response to thermal annealing is observed. Atomically resolved noncontact atomic force microscopy (nc-AFM) shows that intrinsic point defects on the as-cleaved surface migrate at temperatures above $200{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$. At $400{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}\text{--}500{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$, a disordered surface layer forms, albeit still with a $(1\ifmmode\times\else\texttimes\fi{}1)$ pattern in low-energy electron diffraction (LEED). Purely ${\mathrm{TiO}}_{2}$-terminated surfaces, prepared by wet-chemical treatment, are also disordered despite their $(1\ifmmode\times\else\texttimes\fi{}1)$ periodicity in LEED.