Role of grain boundaries in double exchange manganite oxides La 1- xA xMnO 3 (A = Ba, Ca)
Abstract
We report the study of magnetotransport and magnetic properties of manganite oxides La 1- xA xMnO 3 (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} ( ϱP: 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 La 0.67Ba 0.33MnO 2.99 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.
- Publication:
-
Solid State Communications
- Pub Date:
- May 1997
- DOI:
- 10.1016/S0038-1098(97)00031-8
- Bibcode:
- 1997SSCom.102..463J