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, Mark S. Golden*

*Corresponding author for this work

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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 O-2p band alignment as a guiding principle for property design in complex oxide heterointerfaces.
Original languageEnglish
Article number026001
JournalPhysical Review Materials
Volume4
Issue number2
DOIs
Publication statusPublished - 10 Feb 2020

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