Empirical relationship between x-ray photoemission spectra and electrical conductivity in a colossal magnetoresistive manganite La_{1- x}Sr_xMnO₃

By using laboratory x-ray photoemission spectroscopy (XPS) and hard x-ray photoemission spectroscopy (HX-PES) at a synchrotron facility, we report an empirical semi-quantitative relationship between the valence/core-level x-ray photoemission spectral weight and electrical conductivity in La _1-xSr_xMnO₃ as a function of x. In the Mn 2p_3/2 HX-PES spectra, we observed the shoulder structure due to the Mn³⁺ well-screened state. However, the intensity at x = 0.8 was too small to explain its higher electrical conductivity than x = 0.0, which confirms our recent analysis on the Mn 2p_3/2 XPS spectra. The near-Fermi level XPS spectral weight was found to be a measure of the variation of electrical conductivity with x in spite of a far lower energy resolution compared with the energy scale of the quasiparticle (coherent) peak because of the concurrent change of the coherent and incoherent spectral weight.