多晶La_(0.49)Sr_(0.51)(Mn_(1-x)Nb_x)O_3的磁电阻研究  

A study on the magnetoresistance of polycrystalline La_(0.49)Sr_(0.51)(Mn_(1-x)Nb_x)O_3

作　　者：柳文军[1] 朱德亮[1] 舒启清[1] 马晓翠[1] Troyanchuk I O 

机构地区：[1]深圳大学理学院 [2]白俄罗斯科学院固体物理研究所

出　　处：《深圳大学学报（理工版）》2005年第4期297-302,共6页Journal of Shenzhen University(Science and Engineering)

基　　金：深圳市科技计划基金资助项目(200448);深圳大学科研基金资助项目

摘　　要：采用四探针法测量多晶La0.49Sr0.51(Mn1-xNbx)O3(x=0,0.05,0.15和0.25)在磁场下的电阻率温度曲线.实验结果显示:①在0.45T磁场下,对于x=0和x=0.25的样品,几乎观察不到磁电阻(Magnetoresistance,MR)效应,而对于x=0.05和x=0.15的样品,磁电阻效应较明显.这种差异可能与样品中铁磁相是否占主导作用有关;②比较x=0.05和x=0.15这两种样品的MR机制,前者可能与载流子在弱连接晶界上的自旋相关散射有关,且其主要是非本征的;而后者主要是本征的.The temperature dependences of the resistivities for polycrystalline La0.49Sr0.51（Mn1-xNbx）O3 （x = 0, 0.05, 0. 15, and 0. 25） under magnetic fields were measured by the four-point probe method. The experimental results show that under 0. 45T field, the magnetoresistances （MR） for x = 0 and 0. 25 are almost not observed, and that, in contrast, MR for x =0. 05 and 0. 15 are obvious. The above results can be ascribed to how predominant the ferromagnetic （FM）phase is in the samples. The comparisons between MR mechanisms of x = 0. 05 and x = 0. 15 cases manifest that the former is mainly extrinsic, which probably originates from the spin-dependent scattering of the carriers at the weak-link grain boundaries, and that the latter is mainly intrinsic.

关 键 词：多晶La0.49Sr0.51(Mn1-xNbx)O3 庞磁电阻 自旋极化电子输运 

分 类 号：O513[理学—低温物理]