Transport and Magnetic Properties of Nanosized La_(0.6)Sm_(0.1)Sr_(0.3)MnO_3+xCoO Composites  

作　　者：陈水源 叶晴莹 赖恒 黄尚波 黄志高 

机构地区：[1]Department of Physics, Fujian Normal University, Fuzhou 350007,China

出　　处：《Journal of Rare Earths》2006年第6期788-792,共5页稀土学报（英文版）

基　　金：Project supported by NSFof Fujian Province (E0320002 ,2005K020) and Fumiao Foundation of Fujian Normal University (12F032)

摘　　要：The composites La0.6Sm0. 1Sr0.3MnO3 ＋ x CoO （x = 0.0, 0.1, 0.2, 0.3, 0.4 mol）, named as A x 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 Tpat which the p peak is located. It has been concluded that the resistivity below Tp fits well with the equation ρ = ρ0 ＋ ρ2 T^2 ＋ ρ4.5 T^4.5, 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.The composites La0.6Sm0. 1Sr0.3MnO3 ＋ x CoO （x = 0.0, 0.1, 0.2, 0.3, 0.4 mol）, named as A x 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 Tpat which the p peak is located. It has been concluded that the resistivity below Tp fits well with the equation ρ = ρ0 ＋ ρ2 T^2 ＋ ρ4.5 T^4.5, 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.

关 键 词：tunneling magnetoresistance MANGANITES composite materials PERCOLATION rare earths 

分 类 号：O482.53[理学—固体物理]