Temperature-dependent soft x-ray photoemission and absorption studies of charge disproportionation in La1-xSrxFeO3

Hiroki Wadati, Akira Chikamatsu, Ryuji Hashimoto, Masaru Takizawa, Hiroshi Kumigashira, Atsushi Fujimori, Masaharu Oshima, Mikk Lippmaa, Masashi Kawasaki, Hideomi Koinuma

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17 Citations (Scopus)

Abstract

We have measured the temperature dependence of the photoemission and x-ray absorption spectra of La1-xSrxFeO3 (LSFO) epitaxial thin films with x = 0.67, where charge disproportionation (3Fe 3.67+ → 2Fe3+ + Fe5+) resulting in long-range spin and charge ordering is known to occur below TCD = 190 K. With decreasing temperature we observed gradual changes of the spectra with spectral weight transfer over a wide energy range of ∼5 eV. Above T CD the intensity at the Fermi level was relatively high compared to that below TCD but still much lower than that in conventional metals. We also found a similar temperature dependence for x = 0.4, and to a lesser extent for x = 0.2. These observations suggest that a local charge disproportionation occurs not only in the x = 0.67 sample below TCD but also over a wider temperature and composition range in LSFO. This implies that the tendency toward charge disproportionation may be the origin of the unusually wide insulating region of the LSFO phase diagram.

Original languageEnglish
Article number054704
Journaljournal of the physical society of japan
Volume75
Issue number5
DOIs
Publication statusPublished - 2006 May
Externally publishedYes

Keywords

  • Charge disproportionation
  • LaSrFeO
  • Photoemission spectroscopy
  • Spectral weight transfer
  • Temperature dependence
  • Thin films
  • Wide insulating region

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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