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Electronic tuning of two metals and colossal magnetoresistances in EuWO1+ xN2- x perovskites

journal contribution
posted on 24.04.2015 by Minghui Yang, Judith Oro-Sole, Anna Kusmartseva, Alba Fuertes, J. Paul Attfield
A remarkable electronic flexibility and colossal magnetoresistance effects have been discovered in the perovskite oxynitrides EuWO1+xN 2-x. Ammonolysis of Eu2W2O9 yields scheelite-type intermediates EuWO4-yNy with a very small degree of nitride substitution (y = 0.04) and then EuWO1+xN 2-x perovskites that show a wide range of compositions -0.16 < x < 0.46. The cubic lattice parameter varies linearly with x, but electron microscopy reveals a tetragonal superstructure. The previously unobserved x < 0 regime corresponds to oxidation of Eu (hole doping of the Eu:4f band), whereas x > 0 materials have chemical reduction of W (electron doping of the W:5d band). Hence, both the Eu and W oxidation states and the hole/electron doping are tuned by varying the O/N ratio. EuWO1+xN2-x phases order ferromagnetically at 12 K, and colossal magnetoresistances (CMR) are observed in the least doped (x = -0.04) sample. Distinct mechanisms for the hole and electron magnetotransport regimes are identified. © 2010 American Chemical Society.

Funding

This work was supported by the Ministerio de Ciencia e Innovacio´n (grants MAT2008-04587 and PR2008- 0164) and the Generalitat de Catalunya, Spain, and EPSRC, the Royal Society, EaStCHEM, and the Leverhulme Trust, U.K.

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  • Science

Department

  • Physics

Published in

Journal of the American Chemical Society

Volume

132

Issue

13

Pages

4822 - 4829

Citation

YANG, M. ... et al, 2010. Electronic tuning of two metals and colossal magnetoresistances in EuWO1+ xN2- x perovskites. Journal of the American Chemical Society, 132 (13), pp. 4822 - 4829.

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© American Chemical Society

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This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2010

Notes

This article is closed access.

ISSN

0002-7863

eISSN

1520-5126

Language

en

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