Transport and Magnetic Properties of Nanosized La0.6Sm0.1Sr0.3MnO3+xCoO Composites
来源期刊：JOURNAL OF RARE EARTHS2006年第6期
论文作者：Ye Qingying Chen Shuiyuan Huang Zhigao Lai Heng Huang Shangbo
Key words：tunneling magnetoresistance; manganites; composite materials; percolation; rare earths;
Abstract: The composites La0.6Sm0.1Sr0.3MnO3+xCoO (x=0.0, 0.1, 0.2, 0.3, 0.4 mol), named as Ax samples, were synthesized by the sol-gel technique to derive homogeneous CoO-coated composites. CoO addition induces an increase of resistivity (ρ) and a decrease of Curie temperature (TC), magnetization, and TP at which the ρ peak is located. It has been concluded that the resistivity below TP fits well with the equation ρ=ρ0 +ρ2T2 +ρ4.5T4.5, indicating the importance of grain/domain boundary effects, the electron-electron scattering process, and the two magnon scattering process. On the other hand, the paramagnetic insulating region may be explained by using adiabatic small polaron hopping mechanism, thereby indicating that polaron hopping might be responsible for the conduction mechanism. Magnetoresistance results were explained by a two-level model of tunneling MR and percolation model.
Ye Qingying1，Chen Shuiyuan1，Huang Zhigao1，Lai Heng1，Huang Shangbo1
(1.Department of Physics, Fujian Normal University, Fuzhou 350007, China)
Abstract:The composites La0.6Sm0.1Sr0.3MnO3+xCoO (x=0.0, 0.1, 0.2, 0.3, 0.4 mol), named as Ax samples, were synthesized by the sol-gel technique to derive homogeneous CoO-coated composites. CoO addition induces an increase of resistivity (ρ) and a decrease of Curie temperature (TC), magnetization, and TP at which the ρ peak is located. It has been concluded that the resistivity below TP fits well with the equation ρ=ρ0 +ρ2T2 +ρ4.5T4.5, indicating the importance of grain/domain boundary effects, the electron-electron scattering process, and the two magnon scattering process. On the other hand, the paramagnetic insulating region may be explained by using adiabatic small polaron hopping mechanism, thereby indicating that polaron hopping might be responsible for the conduction mechanism. Magnetoresistance results were explained by a two-level model of tunneling MR and percolation model.
Key words:tunneling magnetoresistance; manganites; composite materials; percolation; rare earths;
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