Transport properties of Ce-doped RMnO{sub 3} (R=La, Pr, and Nd) manganites
- Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta 700 064 (India)
In Ce-doped RMnO{sub 3} the rare earth (R) is partially replaced with cerium ions instead of divalent alkaline-earth metals. These compounds are very sensitive to annealing. The resistivity and thermoelectric power (TEP, S) of R{sub 0.7}Ce{sub 0.3}MnO{sub 3} (R=La, Pr, and Nd) have been studied as a function of annealing conditions. They show a ferromagnetic to paramagnetic transition, and a resistive peak near T{sub c}, marking a metal-insulator (MI) transition. A pronounced giant magnetoresistance effect is also observed in these compounds, and T{sub c} can be changed by annealing in various atmospheres. The {rho}(T) curve of oxygen overdoped samples shows double peaks along with a hysteresis loop (in the heating and cooling cycles), which bears the signature of the first-order nature of the transition. The thermopower of as-prepared samples show a peak near the MI transition, and changes sign from positive to negative at temperatures below the ferromagnetic transition. The magnitude of S at low temperatures is enhanced to an abnormally large value. With increasing of oxygen content, several characteristic features develop in the temperature dependence of the thermopower which is consistent with the resistive behavior. At high temperatures, the resistivity and thermopower follow the predictions of the Emin-Holstein theory of adiabatic polaron hopping. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 554366
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 56, Issue 23; Other Information: PBD: Dec 1997
- Country of Publication:
- United States
- Language:
- English
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