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.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
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.~~
关键词
X射线衍射
微结构
应变
物理性能
X-ray diffraction, microstructures, strain, physical properties
