Evaluation of electrical conductivity of a perovskite-type oxide La_1-xSr_xMnO₃ by x-ray photoemission spectroscopy

Abstract

This paper describes the core-level electronic structure of La_1-xSr_xMnO₃ by laboratory x-ray photoelectron spectroscopy (Lab-XPS). For the first time, by Lab-XPS, we have succeeded in observing the shoulder structure in the lower binding energy side of Mn 2p_3/2 core-level spectra which has been observed only in the hard x-ray photoelectron spectroscopy (HX-PES). Then Mn³⁺, Mn⁴⁺, and the shoulder structure on the Mn 2p_3/2 are separated by a multi-peak analysis. The result of considering Mn³⁺ ⁄ Mn⁴⁺ ratio determined by the Sr fraction (x), it was found that a presence of intensity on Mn 2p_3/2 spectra other than the above. The peak was identified as the well-screened peak from the Mn⁴⁺ sites, consequently the sum of the well-screened weight of the Mn³⁺ sites and Mn⁴⁺ sites was related to the electrical conductivity with x.