La0.8Ca0.2MnO3/SrTiO3薄膜厚度对其结构及磁学性能的影响

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La_0.8Ca_0.2MnO₃/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.LC 关键词： X射线衍射 微结构 应变 物理性能

Thickness effect on structure and magnetic properties of La0.8Ca0.2MnO3/SrTiO3 films

The thickness dependence of strain and magnetic properties of La_0.8Ca_0.2MnO₃ (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 q_z 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 T_MI is enhanced, and the MR is weakened.