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Institut für Angewandte Physik,
TU Wien, 1040 Wien, Austria
Center for Photon Science, Paul Scherrer Institut, Villigen, Switzerland
European Theoretical Spectroscopy Facility, Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
Institut de Physique, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
WEL Research Institute, Wavre, Belgium.
MAX IV Laboratory, Lund University, Lund, Sweden.
Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic.
Two-dimensional electron liquids (2DELs) have increasing technological relevance for ultrafast electronics and spintronics, yet significant gaps in their fundamental understanding are exemplified on the prototypical SrTiO3. We correlate the exact SrTiO3(001) surface structure with distinct 2DELs through combined microscopic angle-resolved photoemission spectroscopy and non-contact atomic force microscopy on truly bulk-terminated surfaces that alleviate structural uncertainties inherent to this long-studied system. The SrO termination is shown to develop a 2DEL following the creation of oxygen vacancies, unlike the intrinsically metallic TiO2 termination. Differences in degeneracy of the 2DELs, with nearly the same band filling and identical band bending, are assigned to polar distortions of the Ti atoms in combination with spin order, supported with the extraction of fundamental electron-phonon coupling strength. These results not only resolve the ambiguities regarding 2DELs on SrTiO3 thus far, but also pave the way to manipulating band filling and spin order in oxide 2DELs in general.
Corresponding authors: Igor Sokolović and Hugo Dil. Reprints also available from Ulrike Diebold (diebold).
You can download a PDF file of this open-access article from Nature Communications or from the IAP/TU Wien web server.