Co valence transformation in isopolar LaCoO3/LaTiO3 perovskite heterostructures via interfacial engineering

Georgios Araizi-Kanoutas, Jaap Geessinck, Nicolas Gauquelin, Steef Smit, Xanthe H. Verbeek, Shrawan K. Mishra, Peter Bencok, Christoph Schlueter, Tien-Lin Lee, Dileep Krishnan, Jarmo Fatermans, Jo Verbeeck, Guus Rijnders, Gertjan Koster, and Mark S. Golden
Phys. Rev. Materials 4, 026001 – Published 10 February 2020
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Abstract

We report charge transfer up to a single electron per interfacial unit cell across nonpolar heterointerfaces from the Mott insulator LaTiO3 to the charge transfer insulator LaCoO3. In high-quality bi- and trilayer systems grown using pulsed laser deposition, soft x-ray absorption, dichroism, and scanning transmission electron microscopy-electron energy loss spectroscopy are used to probe the cobalt-3d electron count and provide an element-specific investigation of the magnetic properties. The experiments show the cobalt valence conversion is active within 3 unit cells of the heterointerface, and able to generate full conversion to 3d7 divalent Co, which displays a paramagnetic ground state. The number of LaTiO3/LaCoO3 interfaces, the thickness of an additional, electronically insulating “break” layer between the LaTiO3 and LaCoO3, and the LaCoO3 film thickness itself in trilayers provide a trio of control knobs for average charge of the cobalt ions in LaCoO3, illustrating the efficacy of O2p band alignment as a guiding principle for property design in complex oxide heterointerfaces.

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  • Received 2 September 2019
  • Revised 28 November 2019
  • Accepted 14 January 2020

DOI:https://doi.org/10.1103/PhysRevMaterials.4.026001

©2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Georgios Araizi-Kanoutas1,*,†, Jaap Geessinck2,*, Nicolas Gauquelin3, Steef Smit1, Xanthe H. Verbeek1, Shrawan K. Mishra4, Peter Bencok5, Christoph Schlueter6, Tien-Lin Lee5, Dileep Krishnan3, Jarmo Fatermans3,7, Jo Verbeeck3, Guus Rijnders2, Gertjan Koster2, and Mark S. Golden1,‡

  • 1Van der Waals–Zeeman Institute for Experimental Physics, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
  • 2MESA+ Institute for Nanotechnology, University of Twente, Faculty of Science and Technology, P.O. Box 217, 7500 AE Enschede, Netherlands
  • 3Electron Microscopy for Materials Science, University of Antwerp, Campus Groenenborger, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
  • 4School of Materials Science and Technology, Indian Institute of Technology (BHU), Varanasi 221 005, India
  • 5Diamond Light Source, Limited, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
  • 6PETRA III, DESY Photon Science, Notkestrasse 85, 22607 Hamburg, Germany
  • 7Imec-Vision Lab, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, 2610 Wilrijk, Belgium

  • *These authors contributed equally to this work.
  • g.araizikanoutas@uva.nl
  • m.s.golden@uva.nl

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Issue

Vol. 4, Iss. 2 — February 2020

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