Correlation of high temperature X-ray photoemission spectral features and conductivity of epitaxially strained (La0.8Sr0.2)0.95Ni0.2Fe0.8O3/SrTiO3(110)

TL;DR

This study links temperature-induced changes in electrical conductivity of a strained thin film to valence band and core level spectral features, revealing both reversible and irreversible electronic and structural transitions.

Contribution

It provides a detailed correlation between spectral features and conductivity changes in a complex oxide thin film under strain and temperature variations.

Findings

Irreversible jump at 823 K linked to Fe reduction and hole depletion.

Reversible jump at 573 K associated with structural changes.

Spectroscopic evidence supports electronic and structural transition mechanisms.

Abstract

Reversible and irreversible discontinuities at around 573 K and 823 K in the electric conductivity of a strained 175 nm thin film of (La0.8Sr0.2)0.95Ni0.2Fe0.8O3-{\delta} grown by pulsed laser deposition on SrTiO3 (110) are reflected by valence band changes as monitored in photoemission and oxygen K-edge x-ray absorption spectra. The irreversible jump at 823 K is attributed to depletion of doped electron holes and reduction of Fe4+ to Fe3+, as evidenced by oxygen and iron core level soft x-ray spectroscopy, and possibly of a chemical origin, whereas the reversible jump at 573 K possibly originates from structural changes.