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Doping effects on the valence band of Tl2Mn2O7 pyrochlores: Relation to magnetoresistance
- Source :
- Applied Physics Letters. 84:4209-4211
- Publication Year :
- 2004
- Publisher :
- AIP Publishing, 2004.
-
Abstract
- Photoemission and x-ray absorption near edge spectroscopy measurements have been performed in Tl2Mn2O7 oxides doped with 10% different ions, Bi, Cd, or Sb, which produce colossal changes in the magnetoresistance values. The contributions to the valence band related to Mn, O, and the doping ions have been obtained. We found that the paramagnetic phase of doped Tl pyrochlores is charge-transfer insulator type with oxygen character of the upper edge of the valence band. Bi 6s and Cd 4d orbitals lie also at the upper edge of the valence band. Mn valence is identical for all samples while oxygen content varies to compensate for the charge introduced by doping. The density of carriers, which is correlated to the magnetoresistance values, is determined by the density of states near the Fermi level provided by Tl and O content.
- Subjects :
- Valence (chemistry)
Colossal magnetoresistance
Physics and Astronomy (miscellaneous)
Condensed matter physics
Magnetoresistance
Band gap
Chemistry
Fermi level
Doping
Semimetal
Condensed Matter::Materials Science
symbols.namesake
symbols
Condensed Matter::Strongly Correlated Electrons
Quasi Fermi level
Subjects
Details
- ISSN :
- 10773118 and 00036951
- Volume :
- 84
- Database :
- OpenAIRE
- Journal :
- Applied Physics Letters
- Accession number :
- edsair.doi...........8a013f258aa506b6c69d89277b7306df
- Full Text :
- https://doi.org/10.1063/1.1755413