Abstract
We report charge transfer up to a single electron per interfacial unit cell across nonpolar heterointerfaces from the Mott insulator to the charge transfer insulator . 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- 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 divalent Co, which displays a paramagnetic ground state. The number of interfaces, the thickness of an additional, electronically insulating “break” layer between the and , and the film thickness itself in trilayers provide a trio of control knobs for average charge of the cobalt ions in , illustrating the efficacy of band alignment as a guiding principle for property design in complex oxide heterointerfaces.
1 More- Received 2 September 2019
- Revised 28 November 2019
- Accepted 14 January 2020
DOI:https://doi.org/10.1103/PhysRevMaterials.4.026001
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