Correlation of conductivity and angle integrated valence band photoemission characteristics in single crystal iron perovskites for 300 K < T < 800 K: Comparison of surface and bulk sensitive methods

TL;DR

This study correlates valence band photoemission spectra with conductivity measurements in iron perovskites across a wide temperature range, revealing insights into electronic structure and transport properties without requiring in-situ sample preparation.

Contribution

It demonstrates that surface-sensitive valence band spectra can reflect bulk electronic and transport changes during temperature-induced phase transitions in iron perovskites.

Findings

Spectral intensity variations correlate with conductivity changes.

Valence band spectra reveal reversible and irreversible phase transitions.

Surface and bulk sensitive methods provide complementary insights.

Abstract

A single crystal monolith of La0.9Sr0.1FeO3 and thin pulsed laser deposited film of La0.8Sr0.2Fe0.8Ni0.2O3 were subject to angle integrated valence band photoemission spectroscopy in ultra high vacuum and conductivity experiments in ambient air at temperatures from 300 K to 800 K. Except for several sputtering and annealing cycles, the specimen were not prepared in-situ.. Peculiar changes in the temperature dependent, bulk representative conductivity profile as a result of reversible phase transitions, and irreversible chemical changes are semi-quantitatively reflected by the intensity variation in the more surface representative valence band spectra near the Fermi energy. X-ray photoelectron diffraction images reflect the symmetry as expected from bulk iron perovskites. The correlation of spectral details in the valence band photoemission spectra (VB PES) and details of the conductivity during temperature variation suggest that valuable information on electronic structure and transport properties of complex materials may be obtained without in-situ preparation.