多晶La0.49Sr0.51(Mn1-xNbx)O3的磁电阻研究-《深圳大学学报理工版》

文章信息/Info

Title:: A study on the magnetoresistance of polycrystalline La0.49Sr0.51（Mn1-xNbx)O3

作者:: 柳文军¹; 2; 朱德亮¹; 2; 舒启清¹; 2; 马晓翠¹; 2; Troyanchuk I O³; 1)深圳大学理学院，深圳518060
2)深圳市特种功能材料重点实验室，深圳518060
3)白俄罗斯科学院固体物理研究所，明斯克220072，白俄罗斯

Author(s):: LIU Wen-jun¹; 2; ZHU De-liang¹; 2; SHU Qi-qing¹; 2; MA Xiao-cui¹; 2; Troyanchuk I O³; 1)College of Science Shenzhen University Shenzhen 518060 P. R. China
2)Shenzhen Key Laboratory of Special Functional Materials, Shenzhen 518060 P. R. China
3)Institute of Solid State Physics National Academy of Sciences of Belarus，Minsk 220072 Belarus

Keywords:: Polycrystalline La_0.49Sr_0.51（Mn_1-xNb^_x)O₃; colossal magnetoresistance; spin-polarized electron transport

摘要:: 采用四探针法测量多晶 La_0.49Sr_0.51 （ Mn_1-xNb_x)O₃ (x=0 , 0. 05 , 0. 1.5 和 0. 25) 在磁场下的电阻率一温度曲线 . 实验结果显示 :① 在 0. 45 T 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 .

Abstract:: The temperature dependences of the resistivities for polycrystalline La_0.49Sr_0.51 （ Mn_1-xNb_x)O₃ (x=0 , 0. 05 , 0. 1.5 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. O5 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 lather is mainly intrinsic.