High-pressure p-p band closure of the negative-delta sign Sr2FeO4 perovskite

M. P. Pasternak*, M. Amanowicz, A. P. Milner, G. Kh Rozenberg, R. D. Taylor, G. R. Hearne, K. E. Brister

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Recent analyses of X-ray photoemission (XPS) spectroscopy performed in some high-valence transition metal (TM) oxide insulators have implied the existence of band gaps of the p-p type, corresponding to dnL + dnL → dn + dnL2 charge fluctuations. This band gap is neither the d-d Mott-Hubbard nor the p-d charge-transfer type common to many insulating TM compounds. Thus, it is expected that upon metallization the magnetic moments and ordering will be barely affected since the d-bands are not directly involved in the band-gap closure. We have investigated high-pressure magnetic, structural, and transport properties of Sr2FeO4 (Fe4+), an antiferromagnetic (TN = 60 K) insulator, using diamond anvil cells up to P = 30 GPa. With the increasing pressure a significant increase in the conductance (σ) is observed and at PM = 19 GPa the compound metallizes as concluded from the onset of a negative slope of σ(T). Magnetic studies performed with 57Fe Mössbauer spectroscopy showed no evidence of a magnetic moment collapse at PM and beyond, up to P = 30 GPa. No structural phase transition occurs up to 30 GPa. The coexistence of magnetic moments and metallic state in this oxide is clear evidence of an intra-ligand p-p gap as proposed by the XPS data analyses.

    Original languageEnglish (US)
    Pages (from-to)1377-1378
    Number of pages2
    JournalJournal of Magnetism and Magnetic Materials
    Volume177-181
    Issue numberPART 2
    DOIs
    StatePublished - Jan 1998

    Keywords

    • High pressure
    • Mössbauer spectroscopy
    • Phase transitions - metal-insulator
    • X-ray diffraction

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics

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