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Søren Ulstrup

Volatile two-dimensional electron gas in ultrathin BaTiO3 films

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  • Peter Lutz, Univ Wurzburg, University of Wurzburg, Rontgen Res Ctr Complex Mat RCCM, Expt Phys 7
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  • Simon Moser, EO Lawrence Berkeley Natl Lab, United States Department of Energy (DOE), Lawrence Berkeley National Laboratory, ALS
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  • Vedran Jovic, EO Lawrence Berkeley Natl Lab, United States Department of Energy (DOE), Lawrence Berkeley National Laboratory, ALS
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  • Young Jun Chang, Seoul Natl Univ, Seoul National University, Dept Phys & Astron, Ctr Theoret Phys
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  • Roland J. Koch, EO Lawrence Berkeley Natl Lab, United States Department of Energy (DOE), Lawrence Berkeley National Laboratory, ALS
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  • Soren Ulstrup
  • Ji Seop Oh, Seoul Natl Univ, Seoul National University, Dept Phys & Astron, Astron Program
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  • Luca Moreschini, EO Lawrence Berkeley Natl Lab, United States Department of Energy (DOE), Lawrence Berkeley National Laboratory, ALS
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  • Sara Fatale, Ecole Polytech Fed Lausanne, Ecole Polytechnique Federale de Lausanne, Inst Phys IPHYS
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  • Marco Grioni, Ecole Polytech Fed Lausanne, Ecole Polytechnique Federale de Lausanne, Inst Phys IPHYS
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  • Chris Jozwiak, EO Lawrence Berkeley Natl Lab, United States Department of Energy (DOE), Lawrence Berkeley National Laboratory, ALS
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  • Aaron Bostwick, EO Lawrence Berkeley Natl Lab, United States Department of Energy (DOE), Lawrence Berkeley National Laboratory, ALS
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  • Eli Rotenberg, EO Lawrence Berkeley Natl Lab, United States Department of Energy (DOE), Lawrence Berkeley National Laboratory, ALS
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  • Hendrik Bentmann, Univ Wurzburg, University of Wurzburg, Rontgen Res Ctr Complex Mat RCCM, Expt Phys 7
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  • Friedrich Reinert, Univ Wurzburg, University of Wurzburg, Rontgen Res Ctr Complex Mat RCCM, Expt Phys 7

We investigate the metallic surface state in ultrathin films of BaTiO3 by angle-resolved photoemission spectroscopy. We find Fermi-surface contours derived from the Ti 3d t(2g) conduction band, similar as in SrTiO3 but with broader spectral features due to enhanced quasiparticle scattering. Oxygen vacancies created in the x-ray beam spot allow for reversible in situ doping control up to surface carrier densities as high as 1014 cm(-2), but vacancy migration into the subsurface at T >= 285 K quenches the surface state. Our analysis suggests that the charge state of oxygen vacancies in ultrathin films is predominantly 2+, which limits charge-carrier trapping and the formation of localized defect states.

Original languageEnglish
Article number094411
JournalPhysical Review Materials
Volume2
Issue9
Number of pages6
ISSN2475-9953
DOIs
Publication statusPublished - 28 Sep 2018
Externally publishedYes

    Research areas

  • THIN-FILMS, SRTIO3, POLARIZATION, SURFACE, FERROELECTRICITY, OXIDES, ARPES

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