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Electronic Tuning of Two Metals and Colossal Magnetoresistances in EuWO1+xN2-x Perovskites.
- Source :
-
Journal of the American Chemical Society . 4/7/2010, Vol. 132 Issue 13, p4822-4829. 8p. - Publication Year :
- 2010
-
Abstract
- A remarkable electronic flexibility and colossal magnetoresistance effects have been discovered in the perovskite oxynitrides EuWO1+xN2-x. Ammonolysis of Eu2W2O9 yields scheelite-type intermediates EuWO4-yNy with a very small degree of nitride substitution (y = 0.04) and then EuWO1+xN2-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 12K, 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. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00027863
- Volume :
- 132
- Issue :
- 13
- Database :
- Academic Search Index
- Journal :
- Journal of the American Chemical Society
- Publication Type :
- Academic Journal
- Accession number :
- 49755410
- Full Text :
- https://doi.org/10.1021/ja910745b