Co valence transformation in isopolar LaCoO<sub>3</sub> / LaTiO<sub>3</sub> perovskite heterostructures via interfacial engineering

ORAL

Abstract

Charge transfer up to a single electron per interfacial unit cell across the non-polar heterointerface consisting of the Mott insulator LaTiO3 and the charge-transfer insulator LaCoO3 was studied in multi-layered films grown by PLD, using element-specific soft X-ray absorption, magnetic dichroism, TEM and hard X-ray photoemission spectroscopies.

We provide robust evidence of systematic and controllable conversion of trivalent to divalent cobalt that occurs within an interfacial region of three unit cells in LaCoO3 as a direct result of the ensuing Fermi energy mismatch, without the presence of dopants or structural modification, in agreement with the theoretical prediction. Through the excellent control of the growth process, the average Co valence is tuned at the nanoscale via a proper choice of the number of LaTiO3|LaCoO3 interfaces and the thickness of LaCoO3. Notably, the insertion of an ultrathin LaAlO3 ‘break’ layer interrupts the charge transfer, highlighting its interfacial nature.

Besides the strong enhancement of the magnetic polarizability due to formation of divalent Co, this technologically-relevant guiding principle illustrates the efficacy of O2p-band alignment for property design in oxide heterointerfaces.

*This research is part of the NWO research programme DESCO.

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Presenters

  • Georgios Araizi-Kanoutas

    • Van der Waals-Zeeman Institute for Experimental Physics, Institute of Physics, University of Amsterdam

Authors

  • Georgios Araizi-Kanoutas

    • Van der Waals-Zeeman Institute for Experimental Physics, Institute of Physics, University of Amsterdam

  • Jaap Geessinck

    • MESA+ Institute, Faculty of Science and Technology, University of Twente

  • Nicolas Gauquelin

    • Electron Microscopy for Materials Science, University of Antwerp
    • Canadian Centre for Electron Microscopy and Department of Materials Science and Engineering, McMaster University

  • Steef Smit

    • Univ of Amsterdam
    • Van der Waals-Zeeman Institute for Experimental Physics, Institute of Physics, University of Amsterdam

  • Xanthe Verbeek

    • Van der Waals-Zeeman Institute for Experimental Physics, Institute of Physics, University of Amsterdam

  • Shrawan Mishra

    • Van der Waals-Zeeman Institute for Experimental Physics, Institute of Physics, University of Amsterdam

  • Peter Bencok

    • Diamond Light Source Ltd, Diamond House, Harwell Science & Innovation Campus

  • Christoph Schlueter

    • Deutsches Elektronensynchrotron DESY, Hamburg, Germany
    • PETRA III, DESY Photon Science

  • Tien-Lin Lee

    • Diamond Light Source
    • Diamond Light Source, UK
    • Diamond Light Source Limited is United Kingdom’s national synchrotron and is a leading scientific facility in the world. They host facilities supporting cutting edge researc
    • Diamond Light Source Ltd, Diamond House, Harwell Science & Innovation Campus

  • Dileep Krishnan

    • Electron Microscopy for Materials Science, University of Antwerp

  • Jo Verbeeck

    • Electron Microscopy for Materials Science, University of Antwerp

  • Guus Rijnders

    • MESA+ Institute, Faculty of Science and Technology, University of Twente

  • Gertjan Koster

    • MESA+ Institute, Faculty of Science and Technology, University of Twente

  • Mark Golden

    • Van der Waals-Zeeman Institute for Experimental Physics, Institute of Physics, University of Amsterdam