open access

https://hdl.handle.net/2115/82293

Unusually Large Thermopower Change from +330 to -185 mu V K-1 of Brownmillerite SrCoO2.5

英語

electronic structure

2020-07-28

American Chemical Society

ACS Applied Electronic Materials

2(7)

2250-2256

Strontium cobalt oxide (SrCoO2.5) has recently attracted increasing attention as its optoelectronic and magnetic properties can be widely controlled using electrochemical oxidation/protonation at room temperature in air. To utilize the versatile properties of SrCoO2.5, it is essential to evaluate the location of the Fermi energy (E-F) in the electronic structure, which is sensitive to the oxidation state of the Co ions. Here, we show that thermopower is an excellent measure for analyzing the E-F in SrCoO2.5 epitaxial films. The lattice mismatch causes grain size reduction, which induces a slight increase in the oxidation state of the Co ions due to additional adsorbed oxygen. Although X-ray spectroscopy analyses reveal that the difference of the oxidation state of the Co ions among the samples is small, an unusually large change in thermopower from +330 mu V K-1 (lattice-matched) to -185 mu V K-1 (lattice-mismatched) is observed in the samples due to shifts in the E-F to the lower energy side. The present results demonstrate the excellent sensitivity of thermopower measurements for analyzing the location of E-F in the electronic structure of SrCoO(2.3 )in a practically usable environment.

学術雑誌論文

Accepted Manuscript

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Electronic Materials, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acsaelm.0c00427 .

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