晶粒尺寸对La_(0.83)Na_(0.17)Mn_(0.90)Fe_(0.10)O_3磁性和输运性质的影响  

THE MAGNETIC AND TRANSPORT PROPERTIES OF La_(5/6)Na_ (1/6)Mn_ (0.90)Fe_ ( 0.10)O_ 3 IS INFLUENCED BY GRAIN SIZE

作　　者：刘艳梅[1] 苗继鹏[1] 王先杰[1] 吕喆[1] 隋郁[1] 徐苗[1] 黄晓莉[1] 李玉[1] 刘玉强[1] 武高辉[2] 苏文辉[1] 

机构地区：[1]哈尔滨工业大学理学院凝聚态科学与技术研究中心,哈尔滨150001 [2]哈尔滨工业大学金属基复合材料工程技术研究所,哈尔滨150001

出　　处：《低温物理学报》2006年第2期142-146,共5页Low Temperature Physical Letters

摘　　要：本文研究了纳米相和体相多晶样品La5/6Na1/6Mn0.90Fe0.10O3的结构、磁性和输运性质.XRD谱图表明两样品都是单相的钙钛矿结构.随着晶粒尺寸的减小晶粒表面处的自旋无序增多,使居里温度降低,同时使自旋相关电子在晶界处的散射增强,提高了材料电阻率.纳米粒子的尺寸效应提高了材料的低场磁电阻;晶粒表面自旋无序的增多使电子在晶粒表面的二阶隧道效应增强,提高了高场磁电阻效应.零场电阻率的拟合结果也表明晶粒尺寸的减小使自旋无序增加.This paper presents the preparation of the nanometer phase and the bulk phase polycrystalline La5/6Na1/6Mn0.90Fe0.10O3 by sol-gel, and the investigation of their structure, magnetic and transport properties. XRD results at room temperature show that the structure of the samples is orthorhombic. The decreased grain size increases the surface spin disordered state and the resistivity which originates from the strengthened scatter of the spin correlation electron at the grain boundary, but reduces the Curie temperature. The low field magnetoresistance increases for the size effect of the nanometer particle; meanwhile the high field magnetoresistance increases due to the increase of the spin disorder of the grain surface which strengthens the Second - Order Tunneling effect. The resistivity fitting result also indicates that the decreased grain particle size increases the spin disorder.

关 键 词：磁性 输运性质 双交换相互作用 二阶隧道效应 

分 类 号：O511.4[理学—低温物理]