Metal-insulator transitions in anion-excess LaMnO<SUB>3+δ</SUB> controlled by the Mn<SUP>4+</SUP> content
- Verelst, M.
- Rangavittal, N.
- Rao, C. N. R.
- Rousset, A.
DOIAbstract
LaMnO3+δ samples with Mn4+ content up to 50% have been prepared by different methods. The structure of LaMnO3+δ changes from orthorhombic to cubic (via rhombohedral) with increase in the Mn4+ content. LaMnO3+δ samples containing greater than 20% Mn4+ are ferromagnetic and show resistivity maxima at a temperature Tt which is close to the ferromagnetic Curie temperature. The resistivity maximum is due to the occurrence of a metal-insulator transition. In samples heated to the same temperature, the value of Tt increases with % Mn4+. For a given sample, Tt increases with the temperature of heat treatment due to the increase in particle size. The onset of ferromagnetism in LaMnO3+δ accompanied by an insulator-metal transition...
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