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Magnetic and magnetoresistance properties in rhombohedral perovskite-type compounds

1998; IOP Publishing; Volume: 10; Issue: 33 Linguagem: Inglês

10.1088/0953-8984/10/33/017

1361-648X

Chokri Boudaya, L. Laroussi, E. Dhahri, J.C. Joubert, A. Cheikhrouhou,

Rare-earth and actinide compounds

The effects of monovalent alkali metal substitution into the lanthanide sites in oxides are presented. We report structural features, magnetic and electrical properties of these materials for . The lattice symmetry of the samples is found to be rhombohedral. All the phases are ferromagnetic, with Curie temperatures strongly dependent on x, reaching a maximum around 308 K for . A sharp drop of the resistivity is observed just below the Curie temperature. The ferromagnetic-metallic to paramagnetic-semiconducting transition is explained from the suggested distribution of the cations by the double exchange of pairs at the B-sublattice. Preliminary magnetoresistance measurements (MR) on bulk ceramic samples display an MR effect of the same amplitude as in the case of the alkaline earth substituted La manganites.