Large magnetoresistance in a ferromagnetic cobaltite: The 12H Ba{sub 0.9}CoO{sub 2.6}
- Laboratoire CRISMAT, UMR 6508 CNRS ENSICAEN, 6 bd Marechal Juin, 14050 CAEN Cedex 4 (France)
The magnetic and transport properties of a hexagonal cobaltite related to the perovskite structure have been studied. By combining transmission electron microscopy, X-ray powder diffraction and iodometric titration, it is found that Ba{sub 0.9}CoO{sub 2.6} crystallizes in the 12H structure [P6{sub 3}/mmc, a=5.6612 (1)A and c=28.4627(8)A]. Interestingly, this compound is a ferromagnet with a Curie temperature T{sub C}=50K and a saturation magnetization M{sub S}{sup 2.5K}=1.2{mu}{sub B}/Co. This value is smaller than expected from the effective paramagnetic moment, {mu}{sub eff}=3.7{mu}{sub B}/Co, corresponding to an average spin S{approx}32 per Co, from which one would expect M{sub S}{sup exp.}=3{mu}{sub B}/Co. This suggests either a canted structure or a strong local magnetic anisotropy related to the crystal field of the CoO{sub n} polyhedra. A clear transition in the electrical resistivity is found at T{sub C} consistent with a spin scattering reduction as the sample becomes ferromagnetic. The spin-charge coupling is evidenced by the large negative magnetoresistance effect optimum near T{sub C}=50K, with [100x({rho}{sub H=7T}-{rho}{sub H=0T})/{rho}{sub H=0T}]=-60%.
- OSTI ID:
- 20905320
- Journal Information:
- Journal of Solid State Chemistry, Vol. 179, Issue 6; Other Information: DOI: 10.1016/j.jssc.2006.02.010; PII: S0022-4596(06)00096-X; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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