We report the study of magnetotransport and magnetic properties of manganite oxides La1-xAxMnO3 (A = Ba, Ca). We have observed that polycrystalline manganite shows a different resistivity behavior from that of single crystalline material in that the former shows a small ρ P/ρ 5 K (ρ P: peak resistivity, ρ5 K: resistivity at 5 K) ratio and a large magnetoresistance (MR) effect at T ≪ TC, whereas the latter shows a large ρ P/ρ 5 K ratio and no significant MR at low temperature, due to grain boundary contribution to the resistivity. A La0.67Ba0.33MnO2.99 sample with a polycrystal size of 5 μm showed the grain boundary resistivity 150 times as large as the grain resistivity at 5 K. A possible origin of low-field MR in polycrystalline manganites has been discussed.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Materials Chemistry