La_(0.8)Ca_(0.2)MnO_3/SrTiO_3薄膜厚度对其结构及磁学性能的影响  

Thickness effect on structure and magnetic properties of La_(0.8)Ca_(0.2)MnO_3/SrTiO_3 films

作　　者：张红娣[1] 安玉凯[1] 麦振洪[1] 高炬[2] 胡凤霞[2] 王勇[3] 贾全杰[3] 

机构地区：[1]中国科学院物理研究所国家凝聚态物理实验室,北京100080 [2]香港大学物理系 [3]中国科学院高能物理研究所,北京100049

出　　处：《物理学报》2007年第9期5347-5352,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10274096和10574159);Research Grants Council(RGC) of Hong Kong(批准号:HKU7025/06P)资助的课题.~~

摘　　要：采用多种X射线衍射技术和磁电阻测量技术研究了不同厚度的La0.8Ca0.2MnO3/SrTiO3(LCMO/STO)薄膜的应变状态及其对磁电阻性能的影响.结果表明,在STO(001)单晶衬底上生长的LCMO薄膜沿[00l]取向生长·LCMO薄膜具有伪立方钙钛矿结构,随着薄膜厚度的增加,面内晶格参数增加,垂直于面内的晶格参数减小,晶格参数a和b相近,略小于c·LCMO薄膜内处于应变状态,由于薄膜与衬底的晶格失配,LCMO面内受到拉应力,垂直于面内受到了压应力·LCMO薄膜在qz方向存在轻微的镶嵌结构,并且在qz方向LCMO薄膜与STO衬底存在约0.1°的取向差.薄膜的磁电阻与薄膜的应变状态密切相关,随着薄膜厚度的增加,磁电阻减小.The thickness dependence of strain and magnetic properties of La 0.8 Ca 0.2 MnO3 （LCMO） thin films grown on SrTiO3 （STO） substrates were investigated by X-ray diffraction techniques and magnetic measurements. The results show that all the LCMO films are well oriented in the （00l） direction on the （001） STO substrate. The LCMO thin films have a pseudo-cubic structure. With the film thickness increasing, the in-plane lattice parameters decrease while the out-of-plane lattice parameter increases. The lattice parameter a is close to b, but a little smaller than c. The in-plane strain in the film is tensile due to the lattice mismatch between the LCMO film and STO substrate, whereas that out-of-plane is compressive. The LCMO films have a slightly perceptible mosaic structure along the qz direction, and there exists an angular deviation of about 0.1° between [001] LCMO and [001] STO . The physical properties of the films strongly depend on the film thickness. With the increase of the film thickness the TMI is enhanced, and the MR is weakened.

关 键 词：X射线衍射 微结构 应变 物理性能 

分 类 号：O484.43[理学—固体物理]