Electrical transport and percolation in magnetoresistive manganite/insulating oxide composites:: Case of La0.7Ca0.3MnO3/Mn3O4

被引：33
作者：
Vertruyen, B. [1 ]
Cloots, R. [1 ]
Ausloos, M. [1 ]
Fagnard, J.-F. [1 ]
Vanderbemden, Ph. [1 ]
机构：
[1] Univ Liege, SUPRATECS, B-4000 Cointe Ougree, Belgium
来源：
PHYSICAL REVIEW B | 2007年 / 75卷 / 16期
关键词：
LOW-FIELD MAGNETORESISTANCE;
D O I：
10.1103/PhysRevB.75.165112
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
We report the results of electrical resistivity measurements carried out on well-sintered La0.7Ca0.3MnO3/Mn3O4 composite samples with almost constant composition of the magnetoresistive manganite phase (La0.7Ca0.3MnO3). A percolation threshold (Phi(c)) occurs when the La0.7Ca0.3MnO3 volume fraction is similar to 0.19. The dependence of the electrical resistivity rho as a function of La0.7Ca0.3MnO3 volume fraction (f(LCMO)) can be described by percolationlike phenomenological equations. Fitting the conducting regime (f(LCMO)>Phi(c)) by the percolation power law rho proportional to(f(LCMO)-Phi(C))(-t) returns a critical exponent t value of 2.0 +/- 0.2 at room temperature and 2.6 +/- 0.2 at 5 K. The increase of t is ascribed to the influence of the grain boundaries on the electrical conduction process at low temperature.
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