Transport properties and magnetic behavior in the polycrystalline lanthanum-deficient manganate perovskites ({approx}La{sub 1{minus}x}MnO{sub 3})
- Univ. de Nantes (France)
- Univ. de Bordeaux I, Pessac (France). Inst. de Chimie de la Matiere Condensee de Bordeaux
The rhombohedral lanthanum manganates {approx}La{sub 1{minus}x}MnO{sub 3} (x = 0.0, 0.05, 0.1) were prepared by a soft chemistry route to test first as catalysts. These three weak ferromagnets exhibit a structural transition at T{sub t} slightly below T{sub c}. {approx}La{sub 0.9}MnO{sub 3} undergoes a group-subgroup R{bar 3}c {leftrightarrow} R3c transition most likely of second order. {approx}LaMnO{sub 3} does not show any insulator-to-metal transition, but does show a semiconductor-semiconductor at T{sub t} {approximately} 130 K. Analysis of the transport data (conductivity and thermopower) indicates hopping of polarons at both low and high temperature. An effective magnetic moment of 3.50 {micro}{sub B}/Mn is deduced from the spontaneous magnetization value at 5 K. The slight difference from the spin-only value (3.67 {micro}{sub B}) is assigned to a spin-canting effect which is reflected in the divergence of the FC and ZFC susceptibility curves at low fields (H {le} 10{sup {minus}2} T) and low temperature. Compared with recent results on thin films, the compositions x = 0.05, 0.1 are expected to show magnetoresistive effects as well as a semiconductor-to-metal transition. If it is verified on bulk samples which all contain a similar Mn{sup 4+} content of 35%, the structural transition at T{sub t} could be considered as magnetically driven.
- OSTI ID:
- 514717
- Journal Information:
- Materials Research Bulletin, Vol. 32, Issue 6; Other Information: PBD: Jun 1997
- Country of Publication:
- United States
- Language:
- English
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