X-ray photoelectron spectroscopy study of HgBa2CuO4+δ

Abstract

X-ray photoelectron spectroscopy was used to investigate the oxidation states of Hg and Cu ions in the HgBa2CuO4+δ compound. In contrast to the previous report on the scraped samples [C.S. Gopinath and S. Subramanian, Physica C 232 (1994) 222], our spectra from the fresh surfaces of fractured samples do not show the unusual 3 + oxidation state of Hg ions, while the satellite structure of the Cu 2p3 2 core-level spectrum which indicates the 2 + oxidation state of Cu ions is observed. These results confirm that, in the HgBa2CuO4+δ compound, the Hg atom does not act as an electron reservoir, and that the CuO layers are hole-doped due to the extra oxygens in the HgOδ planes. © 1995.