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Metallic and nonmetallic double perovskites: A case study of {A_2FeReO_6} (A=Ca, Sr, Ba)

Gopalakrishnan, Jagannatha and Chattopadhyay, A and Ogale, SB and Venkatesan, T and Greene, RL and Millis, AJ and Ramesha, K and Hannoyer, B and Marest, G (2000) Metallic and nonmetallic double perovskites: A case study of {A_2FeReO_6} (A=Ca, Sr, Ba). In: Physical Review B, 62 (14). pp. 9538-9542.

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We have investigated the structure and electronic properties of ferrimagnetic double perovskites, {A_2FeReO_6} (A = Ca, Sr, Ba). The A = Ba phase is cubic (Fm3m) and metallic, while the A = Ca phase is monoclinic {P2_1 /n} and nonmetallic. Fe{^57 Mossbauer} spectroscopy shows that iron is present mainly in the high spin S = (5/2) {Fe^3+} state in the Ca compound, while it occurs in an intermediate state between high spin {Fe^2+ and Fe^3+} in the Ba compound. It is argued that a direct {Re t_2g-Re_ t2g} interaction is the main cause for the metallic character of the Ba compound; the smaller size of Ca and the monoclinic distortion (which lifts the degeneracy of {t_2g} states seem to disrupt the Re-Re interaction in the case of the Ca compound, making it nonmetallic for the same electron count.

Item Type: Journal Article
Publication: Physical Review B
Publisher: American Physical Society
Additional Information: Copyright of this article belongs to American Chemical Society.
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 02 Nov 2009 11:31
Last Modified: 19 Sep 2010 04:59
URI: http://eprints.iisc.ac.in/id/eprint/18035

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