Electronic structure and small hole polarons in YTiO3

Jin Yue, Nicholas F. Quackenbush, Iflah Laraib, Henry Carfagno, Sajna Hameed, Abhinav Prakash, Laxman Raju Thoutam, James M. Ablett, Tien Lin Lee, Martin Greven, Matthew F. Doty, Anderson Janotti, Bharat Jalan

Research output: Contribution to journalArticlepeer-review

Abstract

As a prototypical Mott insulator with ferromagnetic ordering, YTiO3 (YTO) is of great interest in the study of strong electron correlation effects and orbital ordering. Here we report the first molecular beam epitaxy (MBE) growth of YTO films, combined with theoretical and experimental characterization of the electronic structure and charge transport properties. The obstacles of YTO MBE growth are discussed and potential routes to overcome them are proposed. DC transport and Seebeck measurements on thin films and bulk single crystals identify p-type Arrhenius transport behavior, with an activation energy of ~ 0.17 eV in thin films, consistent with the energy barrier for small hole polaron migration from hybrid density functional theory (DFT) calculations. Hard X-ray photoelectron spectroscopy measurements (HAXPES) show the lower Hubbard band (LHB) at 1.1 eV below the Fermi level, whereas a Mott-Hubbard band gap of ~1.5 eV is determined from photoluminescence (PL) measurements. These findings provide critical insight into the electronic band structure of YTO and related materials.

Original languageEnglish (US)
JournalUnknown Journal
StatePublished - Aug 28 2020

Keywords

  • Molecular beam epitaxy
  • Mott insulator
  • Mott-Hubbard band gap
  • Small polaron hopping
  • Thermal evaporation
  • Yttrium titanate

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