DOI: 10.1209/epl/i2003-00531-8
Europhys. Lett., 63 (3) , pp. 433-439 (2003)

Temperature dependence of resistivity in polycrystalline manganites

S. L. Yuan, J. Tang, L. Liu, W. Chen, L. F. Zhao, Y. Tian, H. Cao, G. H. Zhang, L. J. Zhang, W. Feng, S. Liu and Z. C. Xia

Huazhong University of Science and Technology - Wuhan 430074, PRC

(Received 15 January 2003; accepted in final form 23 May 2003)

Abstract
Based on the thermal activation and the spin-polarized tunneling, which depend on temperature range and grain separation, the transport phenomenon is discussed for polycrystalline manganites. By averaging over the distribution of grain separation, we derive a general expression of resistivity which in form is similar to a two-component description. A quantitative agreement with the experimental data obtained in polycrystalline La _2/3Ca _1/3MnO ₃ gives a strong support to this model. Some main features dealing with the grain boundary effect in polycrystalline manganites are discussed on the basis of this model.

PACS
73.40.-c - Electronic transport in interface structures.
72.25.-b - Spin polarized transport.
75.47.Gk - Colossal magnetoresistance.

© EDP Sciences 2003