Abstract
We review the distortions of the MnO6 octahedra reduced by magnetization in hole-doped lanthanum manganese perovskites. The systems we consider include the "colossal" magnetoresistance (CMR) samples La1 - xCaxMnO3 (x=0.21, 0.25, 0.30), La0.67Ba0.33MnO3, and a poorer quality La0.67Pb0.33MnO3 sample. We also report preliminary work on three samples of oxygen-doped LaMnO3 + δ and a lanthanum-deficient La0.9MnO3 sample. We find the same exponential relationship between the removal of the distortion and the sample magnetization in the Ba- and Pb-doped CMR samples as was found previously for the Ca-doped samples. The MnO6 distortion in the oxygen-doped materials is found to slightly reduce below the magnetic transition, although much less so than in the CMR samples. Above Tc, the antiferromagnetic LaMnO3.006 sample shows a softer temperature dependence of the Mn-O bond length distribution broadening. Surprisingly, even this sample shows deviations from thermal (Debye) behavior near TN, possibly due to FM coupling within MnO planes.
Original language | English (US) |
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Pages (from-to) | 295-298 |
Number of pages | 4 |
Journal | Journal of Superconductivity and Novel Magnetism |
Volume | 12 |
Issue number | 1 |
State | Published - 1999 |
Keywords
- "colossal" magnetoresistance (CMR)
- Jahn-teller polarons
- LaAMno; laMno
- X-ray-absorption fine-structure (XAFS)
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics