• Editors' Suggestion
  • Rapid Communication

Unexpected termination switching and polarity compensation in LaAlO3/SrTiO3 heterostructures

Guneeta Singh-Bhalla, Pim B. Rossen, Gunnar K. Pálsson, Matthew Mecklenburg, Thomas Orvis, Sujit Das, Yun-Long Tang, Jaganatha S. Suresha, Di Yi, Abhigyan Dasgupta, David Doenning, Victor G. Ruiz, Ajay K. Yadav, Morgan Trassin, John T. Heron, Charles S. Fadley, Rossitza Pentcheva, Jayakanth Ravichandran, and Ramamoorthy Ramesh
Phys. Rev. Materials 2, 112001(R) – Published 21 November 2018
PDFHTMLExport Citation

Abstract

Polar crystals composed of charged ionic planes cannot exist in nature without acquiring surface changes to balance an ever-growing dipole. The necessary changes can manifest structurally or electronically as observed in semiconductors and ferroelectric materials through screening charges and/or domain wall formation. In the case of prototypical polar complex oxides such as the LaAlO3/SrTiO3 system the nature of screening charges for different interface terminations is not symmetric. Electron accumulation is observed near the LaAlO3/TiO2SrTiO3 interface, while the LaAlO3/SrO-SrTiO3 stack is insulating. Here, we observe evidence for an asymmetry in the surface chemical termination for nominally stoichiometric LaAlO3 films in contact with the two different surface layers of SrTiO3 crystals, TiO2 and SrO. Using several element-specific probes, we find that the surface termination of LaAlO3 remains AlO2 irrespective of the starting termination of SrTiO3 substrate surface. We use a combination of cross-plane tunneling measurements and first-principles calculations to understand the effects of this unexpected termination on band alignments and polarity compensation of LaAlO3/SrTiO3 heterostructures. An asymmetry in LaAlO3 polarity compensation and resulting electronic properties will fundamentally limit atomic level control of oxide heterostructures.

  • Figure
  • Figure
  • Figure
  • Figure
  • Received 4 January 2018
  • Revised 26 August 2018

DOI:https://doi.org/10.1103/PhysRevMaterials.2.112001

©2018 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Guneeta Singh-Bhalla1,2, Pim B. Rossen3, Gunnar K. Pálsson2,4,*, Matthew Mecklenburg5, Thomas Orvis6, Sujit Das3, Yun-Long Tang3, Jaganatha S. Suresha7, Di Yi3,†, Abhigyan Dasgupta1, David Doenning8, Victor G. Ruiz8, Ajay K. Yadav3, Morgan Trassin3,‡, John T. Heron3,§, Charles S. Fadley2,4, Rossitza Pentcheva9, Jayakanth Ravichandran6,¶, and Ramamoorthy Ramesh1,2,3,∥

  • 1Department of Physics, University of California, Berkeley, California 94720, USA
  • 2Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  • 3Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
  • 4Department of Physics, University of California, Davis, California 95616, USA
  • 5Core Center of Excellence for Nano Imaging (CNI), University of Southern California, Los Angeles, California 90089, USA
  • 6Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089, USA
  • 7National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  • 8Department of Earth and Environmental Sciences and Center of Nanoscience (CENS), University of Münich, DE-80333 Münich, Germany
  • 9Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47057 Duisburg, Germany

  • *Present address: Department of Physics and Astronomy, Uppsala University, Uppsala, 751 20, Sweden.
  • Present address: Department of Applied Physics, Stanford University, Stanford, CA 94305, USA.
  • Present address: Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland.
  • §Present address: Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
  • Corresponding author: jayakanr@usc.edu
  • Corresponding author: rramesh@berkeley.edu

Article Text (Subscription Required)

Click to Expand

Supplemental Material (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 2, Iss. 11 — November 2018

Reuse & Permissions
Access Options
CHORUS

Article Available via CHORUS

Download Accepted Manuscript

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review Materials

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×