Evidence for oxygen holes due to d-p rehybridization in thermoelectric Sr1-x Rh2 O4

Soft-x-ray photoemission and absorption spectroscopies are employed to investigate the electronic structures of Sr1-x Rh2 O4. Similar to the layered cobaltates such as Na1-x CoO2, a valence-band satellite feature (VBS) occurs at higher binding energy to the O2p band. We find that the VBS resonates at the O1s edge. Additionally, core absorption shows clear x dependence in the O1s edge rather than in the Rh3p edge. These results indicate that the holes in the initial state mainly have O2p character presumably due to d-p rehybridizations affected by Sr2+ vacancy potentials. The resultant inhomogeneous charge texture may have impact on the thermoelectric transport properties at low x.