多晶La_(0.49)Sr_(0.51)(Mn_(1-x)Nb_x)O_3的电输运特性研究  

Studies on transport properties of polycrystalline La_(0.49)Sr_(0.51)(Mn_(1-x)Nb_x)O_3

作　　者：柳文军[1] 舒启清[1] 马晓翠[1] 杜建设[1] 李逢明[1] Troyanchuk I.O 

机构地区：[1]深圳大学理学院,深圳518060 [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）》2004年第4期339-343,共5页Journal of Shenzhen University(Science and Engineering)

基　　金：深圳市科技局资助项目(200214);深圳大学科研基金资助项目

摘　　要：测量了B位掺杂的钙钛矿结构锰氧化物La0 49Sr0 51(Mn1-xNbx)O3(x=0,0 05,0 15和0 25)的电阻率和磁化强度的温度特性.实验结果表明,当Nb5+部分替代B位的Mn4+离子时,电阻率-温度特性由原来单一的半导体型转变成了高温时的半导体(绝缘体)型和低温时的类金属型.随Nb掺杂量增大,电阻率迅速升高3～5个数量级,半导体(绝缘体)-类金属转变温度降低.在掺杂Nb的样品中,只观察到顺磁-铁磁转变,而未观察到铁磁-反铁磁转变.上述实验结果的一种可能解释是掺杂改变了磁有序时电子自旋的排列和空间取向,从而改变载流子被自旋热涨落的散射作用和载流子转移的随机性.The temperature dependences of the resistivity and magnetization of B-site doped polycrystalline La_(0.49)Sr_(0.51)(Mn_(1-x)Nb_x)O_3(x=0, 0.05, 0.15, and 0.25) were measured. The results showed that when Mn^(4+) on B sites were substituted partialy by Nb^(5+), the temperature dependence of the resistivity changed from semiconductor-type at all the measured temperature to semiconductor (insulator)-type at the high temperature and metallike-type at the low temperature. With increasing x, the resistivity increased rapidly by 3～5 orders of magnitude, and the semiconductor (insulator)-metallike transition temperature reduced. The ferromagnetic-antiferromagnetic transition was not observed in Nb doped samples. A possible explanation for the results is that due to the doping, the array and orientation of the spins in the magnetic ordering state are changed, thus the carrier scattering by the thermal spin fluctuations and the randomness of carrier transfer are affected.

关 键 词：La0.49Sr0.51(Mn1-xNb2)O3 电阻率 半导体-金属转变 磁化强度 

分 类 号：O513[理学—低温物理]