Evidence for Oxygen Holes due to d-p Rehybridization in Thermoelectric Sr_{1-x}Rh_{2}O_{4}

TL;DR

This study uses spectroscopic techniques to reveal that oxygen holes in Sr_{1-x}Rh_{2}O_{4} originate from d-p rehybridization influenced by Sr vacancies, affecting its thermoelectric properties.

Contribution

It provides direct spectroscopic evidence for oxygen hole formation due to d-p rehybridization in Sr_{1-x}Rh_{2}O_{4}, linking electronic structure to thermoelectric behavior.

Findings

Oxygen holes mainly have O 2p character.

Valence-band satellite feature resonates at O 1s edge.

Charge inhomogeneity may influence thermoelectric transport.

Abstract

Soft-x-ray photoemission and absorption spectroscopies are employed to investigate the electronic structures of Sr_{1-x}Rh_{2}O_{4}. Similarly to the layered cobaltates such as Na_{1-x}CoO_{2}, a valence-band satellite feature (VBS) occurs at higher binding energy to the O 2p band. We find that the VBS resonates at the O 1s edge. Additionally, core absorption shows clear x dependence in the O 1s edge rather than in the Rh 3p edge. These results indicate that the holes in the initial state mainly have O 2p character presumably due to d-p rehybridizations affected by Sr^{2+} vacancy potentials. The resultant inhomogenous charge texture may have impact on the TE transport properties at low x.