Sr_(1-x)Y_xCoO_3的磁性和电输运性质  

MAGNETISM AND TRANSPORT PROPERTIES OF Sr_(1-x)Y_xCoO_3

作　　者：黄丽[1] 刘丽军[1] 王玉[1] 何军辉[1] 

机构地区：[1]扬州大学物理科学与技术学院,江苏扬州225002

出　　处：《低温物理学报》2013年第1期16-21,共6页Low Temperature Physical Letters

基　　金：国家自然科学基金(批准号:10974170)资助的课题~~

摘　　要：采用传统的固相反应法制备了A位Y掺杂的多晶钙钛矿氧化物Sr1-xYxCoO3(x-0～0.30),系统研究了Y掺杂对体系结构、磁性和电输运性质的影响.X射线衍射结果表明室温下体系经过六方对称到立方对称再到四方对称的结构相变,x=0样品为六方结构,空间群为P63/mmc,0.05≤x≤0.15样品为立方对称结构,空间群为Pm3 m,x≥0.20样品为四方对称结构,空间群为I4/mmm,x=0.20时具有最大矫顽场Hc=4.6kOe.体系在外加磁场为1kOe下表现出如下磁性特征:x=0时Jc=163K,随着掺杂量的增加,转变温度呈现上升趋势,同时反铁磁性也随之增强.所有组分均表现出半导体特征,并且观察到复杂的磁电阻(MR)与温度变化关系:所有组分均表现出+MR与-MR共存的特征,当掺杂量为x=0.1时,在T=370K下表现出测量最大磁电阻的绝对值︱MR︳约为17%.Sr1-xYxCoO3样品遵循可变程传到模型,在150K≤T≤400K温度范围内ln(ρ)与T-1/4呈线性关系.The A site Y-doping perovskite-type oxides Sr1-xYxCo（x-0～0.30） polycrystalline samples have been prepared by conventional solid-state reaction method. The influence of Y-doping on the structure, transport properties and magnetoresistance have been investigated systemataeially. The Xray diffraction indicated that the system studied in the present investigation undergoes structure phase transition at room temperature from hexagonal to cubic and at last to tetragonal symmetry. For x=0, the sample shows a hexagonal structure with P63/mmc space group, while the samples with .05≤x≤0.15 reveal cubic with Pm3m group symmetry, and the samples with P63/mmc reveal tetragonal with 14/mmm group symmetry. The maximum coercive field is 4, 6kOe at x=0. 20. The system shows magnetic properties at the applied field of lkOe： for x=0, the Curie temperature is 163K and with in- creasing of Y-doping, the transition temperature increases, at the same time, the antiferromagnetism is enhanced. All the compositions show a semiconducting-like behavior and some complicated features of temperature dependence of magnetoresistance（MR） are observed： all the compositions show a feature that -MR and --MR coexist. For x= 0. 1, the sample shows a maximum absolute value of MR（about 17%） at 370K. The Sr1-xYxCoO3 samples seemly to obey variable range hopping conduction model showing a linear ln（p） versus T-1/4 dependence at the temperature range 150K≤T≤400K.

关 键 词：Y掺杂 磁电阻 钙钛矿氧化物 磁性 

分 类 号：O482.5[理学—固体物理]