Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 103: Transport: Poster Session

TT 103.39: Poster

Donnerstag, 19. März 2015, 15:00–18:00, Poster B

High quality thin films of BaBiO₃ on SrTiO₃ grown by pulsed laser deposition — •Michael Zapf¹, Martin Stübinger¹, Gang Li², Michael Sing¹, and Ralph Claessen¹ — ¹Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Germany — ²Institut für Theoretische Physik und Astronomie, Universität Würzburg, Germany

Recently, BaBiO₃ (BBO) has been predicted to be a possible candidate for a large gap topological insulator. However, DFT calculations show that the protected surface states are located 2 eV above the Fermi level. To populate these states heavy electron doping is necessary. Conceivable ways to achieve such a doping are, for example, the deposition of alkali metal atoms on thin BBO films or electrostatic doping by applying a gate voltage. As a first step we have been able to fabricate phase-pure BBO on Nb-doped SrTiO₃ (STO) by pulsed laser deposition. High energy electron diffraction (RHEED) shows an island-like growth mode after formation of a wetting layer on the STO substrate, which may be due to the large lattice misfit of BBO and STO. A sharp low energy electron diffraction (LEED) pattern and X-ray diffraction evidence the epitaxial growth of crystalline BBO. In angle integrated photoemission experiments the samples reveal the valence band structure of cleaved undoped BBO single crystals. To our knowledge it is the first time that this could be shown on BBO thin films. Further experiments will elucidate the feasibility of doping electrons into these samples.