Influence of W/Ta substitution at the Mo site on the Fe valence and magnetoresistive properties of Sr2FeMoO6

J. Lindén, T. Yamamoto, H. Yamauchi, M. Karppinen*

*Corresponding author for this work

Research output: Contribution to journalConference articleScientificpeer-review

3 Citations (Scopus)

Abstract

High-purity Sr2Fe(Mo1-xTx)O6 samples with T = W, Ta and 0≤x≤1 were synthesized using a solid-state reaction scheme. During synthesis a strongly reducing atmosphere was maintained by confining the precursors and an Fe/FeO oxygen getter to fused-silica tubes. Sample quality and homogeneity were confirmed by X-ray diffraction and energy-dispersive X-ray analysis. For the non-substituted samples, 57Fe Mössbauer spectra indicate that the Fe ions occupy a mixed-valence state of +2.5. W6+ forces increasing amounts of Fe to enter the +2 state, whereas Ta5+ substitution yields increasing amounts of Fe3+. Non-substituted samples exhibit a characteristic tunneling-type magnetoresistance below TC. Both W and Ta substitution were found to enhance the low-temperature magnetoresistance around the Néel temperature of the pure Sr2FeWO6 and Sr2FeTaO6 phases, respectively. The enhancement is related to the colossal magnetoresistance effect at the paramagnetic to antiferromagnetic transitions of areas rich in W or Ta.

Original languageEnglish
Pages (from-to)787-788
Number of pages2
JournalPhysica B: Condensed Matter
Volume312-313
DOIs
Publication statusPublished - 1 Mar 2002
MoE publication typeA4 Article in a conference publication
EventInternational Conference on Strongly Correlated Electrons - Ann Arbor, United States
Duration: 6 Aug 20026 Aug 2002

Keywords

  • Fe Mössbauer spectroscopy
  • Tunneling magnetoresistance
  • Valence fluctuations

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