Valence state of Ru at the Mn sites in Pr0.5Sr0.5MnO3

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Published under licence by IOP Publishing Ltd
, , Citation J S Kim et al 2005 Phys. Scr. 2005 498 DOI 10.1238/Physica.Topical.115a00498

1402-4896/2005/T115/498

Abstract

The valence of Ru at the Mn sites in Pr0.5Sr0.5MnO3 has been studied using Ru K- and LIII-edge x-ray absorption near edge structure (XANES) spectroscopy. In comparison with XANES of tetravalent and pentavalent ruthenates, it was found that the Mn-site doped Ru is mainly in tetravalent state with a small amount of pentavalent Ru. This result indicates that the change of carrier density with Ru doping is not sufficient to induce the drastic enhancement of ferromagnetism observed in transport properties of Ru-doped Pr0.5Sr0.5MnO3. The mixed valence state of doped Ru suggests that 4d orbitals of Ru are involved in electronic transport of the Mn3+-O-Mn4+ network with the valence fluctuation Ru5+ + Mn3+ ↔ Ru4+ + Mn4+. The prime role of Ru has been discussed in terms of Mn valence change and magnetic interactions between Mn and doped Ru ions.

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10.1238/Physica.Topical.115a00498