Empirical relationship between x-ray photoemission spectra and electrical conductivity in a colossal magnetoresistive manganite La1−xSrxMnO3

Abstract

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/corelevel x-ray photoemission spectral weight and electrical conductivity in La 1−x Sr x MnO 3 as a function of x. In the Mn 2p 3/2 HX-PES spectra, we observed the shoulder structure due to the Mn 3+ 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.

Energy Level Alignment and Cation Charge States at the LaFeO3/LaMnO3 (001) Heterointerface

“…The low binding energy shoulder of the Mn 2p 3/2 peak has previously been associated with metallic Mn 0 and metallicity in Mn 3+ compounds . However, no related spectral intensity at E F is observed in the HAXPES valence band spectra in Figure b (which are also shown on a logarithmic intensity scale in Figure S5, Supporting Information).…”

“…Both observations contradict the attribution of the prominent low binding energy shoulder of the Mn 2p 3/2 spectra of the (LFO) 4 /(LMO) 44 and (LFO) 7 /(LMO) 47 samples to metallic Mn 0 . Hence we ascribe this feature to well‐screened bulk Mn 3+ states …”

Electronic structure of buried LaNiO3 layers in (111)-oriented LaNiO3/LaMnO3 superlattices probed by soft x-ray ARPES

“…The optical gap of LMO has been reported between 0.6 and 1 eV and previous XPS measurements revealed the onset of the density of states at 0.5 eV below the Fermi level. [48][49][50][51] Hence, we conclude that the peak located 0.1 eV below E F corresponds to e g states in Ni with the feature at 1 eV likely having contributions from both LMO and LNO. Figure 4(b) depicts the region of the spectra close to the Fermi level where the loss of spectral weight at E F for the [LNO 7 /LMO 5 ] 6 sample is evident.…”

Identification of hidden orbital contributions in the La0.65Sr0.35MnO3 valence band

“…The approach used in the present work thus allows us the identification of orbital components that were unexpected according to previous experiments and that can be particularly relevant for describing transport phenomena. Indeed, the fact that the more delocalized Mn 4s and the O 2s states are essential for describing the region close to the Fermi level nicely explains the fact that the near Fermi level spectral weight can be used as a measure of the variation of electrical conductivity better in the HAXPES than in the SXPES regime [42].…”