La_(0.67)Pb_(0.33)MnO_3的磁性及输运特性  

Magnetic and transport properties of perovskite La_(0.67)Pb_(0.33)MnO_3

作　　者：肖春涛[1] 韩立安[1] 薛德胜[1] 赵俊慧[1] H.Kunkel G.Williams 

机构地区：[1]兰州大学磁学与磁性材料教育部重点实验室,兰州730000 [2]DepartmentofPhysicsandAstronomy,UniversityofManitoba

出　　处：《物理学报》2003年第5期1245-1249,共5页Acta Physica Sinica

基　　金：高等学校重点实验室访问学者基金资助的课题~~

摘　　要：利用固相反应烧结法制备了La0 6 7Pb0 33MnO3单相多晶样品 .研究了其结构、磁性及输运特性 .结果表明 ,样品呈菱面相晶体结构 ,空间群为R3C ,居里温度TC( =3 5 3K)非常接近TMI( =3 60K) .在居里温度附近 ,发生铁磁 -顺磁转变 ,导电特性由金属特征向半导体特征过渡 .磁电阻在居里点达到极大值 .当H =1 6T时 ,磁电阻的极大值为14 5 % ;当H =0 8T时 ,磁电阻的极大值为 9% .输运性质表明 ,T<TMI 时 ,低温区电阻率满足公式 ρ(T) =ρ0 +ρT2 5,此输运机理是由磁流子散射造成的 ;当T >TMI 时 。Single-phase polycrystalline samples of La 0 67Pb 0 33MnO 3 were prepared by conventional solid-state reaction method. The crystal structure and magnetic and transport properties are investigated. The structure revealed by the room temperature x-ray powder diffraction is rhombohedral(R3C), and the Curie temperature is very close to T MI(=360K). At the Curie point, the magnetic properties show the transition from ferromagnetic to paramagnetic, and the conductivity changes from metal to semiconducting. The resistivity decreases with increasing magnetic field. Magnetoresistance reaches a maximum at the Curie point. The maximum magnetoresistance is 14^5% at H=1^2MA/m, and 9% at H=0^6MA/m. The transport results show that the transport data satisfy ρ(T)=ρ 0+ρT 2.5 for T<T MI, but agree with the polaron model when T>T MI. This phenomenon is due to the magon-carrier scattering.

关 键 词：La0.67Pb0.33MnO3 磁性 输运特性 固相反应烧结法 铅掺杂 钙钛石型锰氧化物 磁电阻效应 居里温度 

分 类 号：O482.5[理学—固体物理]