Issue 15, 2023

Strain-induced Mn valence state variation in CaMnO3−δ/substrate interfaces: electronic reconstruction versus oxygen vacancies

Abstract

This study investigates the nanoscale crystalline and electronic structures of the interfaces between CaMnO3−δ and substrates such as SrTiO3 (001) and LaAlO3 (001) by employing advanced transmission electron microscopy and electron energy loss spectroscopy techniques. The objective is to comprehend the influence of different strains on the Mn valence state. Our findings reveal that the Mn valence state remains relatively stable in the region of a weakly tensile-strained interface, whereas it experiences a significant decrease from Mn4+ to Mn2.3+ in the region of a strongly tensile-strained interface. Although this reduction in valence appears to be consistent with the electron reconstruction scenario, the observed increase in the out-of-plane lattice constant at the interface implies the accumulation of oxygen vacancies at the interface. Consequently, the present study offers a comprehensive understanding of the intricate relationships among the Mn valence state, local structure, and formation of oxygen vacancies in the context of two distinct strain cases. This knowledge is essential for tailoring the interface properties and guiding future developments in the field of oxide heterostructures.

Graphical abstract: Strain-induced Mn valence state variation in CaMnO3−δ/substrate interfaces: electronic reconstruction versus oxygen vacancies

Article information

Article type
Paper
Submitted
31 Mar 2023
Accepted
26 Jun 2023
First published
04 Jul 2023
This article is Open Access
Creative Commons BY license

Nanoscale Adv., 2023,5, 3887-3895

Strain-induced Mn valence state variation in CaMnO3−δ/substrate interfaces: electronic reconstruction versus oxygen vacancies

V. Hoang, N. Lee and H. Kim, Nanoscale Adv., 2023, 5, 3887 DOI: 10.1039/D3NA00206C

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