Nanostructure and low-dimensional properties of CMR materials

CMR材料的纳米结构和低维特性

• 批准号: 10650007
• 负责人: MATSUI Masaaki
• 金额: $ 2.24万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650007/
• 关键词: Magnetoresistance; Ferromagnet; Epitaxial film; Low-dimensionality; Mn oxide; Nanostructure; Perovskite; Tunneling effect; ペロブスカイト型化合物

The colossal magnetoresistance (CMR) ferromagnets of perovskite series LaィイD2n-nxィエD2CaィイD21+nxィエD2MnィイD2nィエD2ィイD23+1ィエD2 (n=2,3, and ∞) have been examined with respected to their electrical and magnetic properties. Results on the transport properties of epitaxial a-axis thin film samples with a fixed carrier concentration (x=0.3) have indicated that a reduction in the number of layers results in systematic changes in the various features. These include an increase in resistivity, a decrease in resistivity peak temperature TcィイD1pィエD1 corresponding to the metal-insulator transition, an enhancement of the maximum MR near TcィイD1pィエD1, and an increase in low temperature intrinsic MR. In order to explain the variation in these features with the number of MnOィイD12ィエD1 layers, it is necessary to take both c-axis transfer interaction an two dimensional spin fluctuation into account. These insights are important from the view points of basic understanding of the CMR mechanism and their practical applications.The lattice effect of LaィイD2n-nxィエD2CaィイD21+nxィエD2MnィイD2nィエD2OィイD23n+1ィエD2 have been investigated using thin films (n=2 and ∞) grown on various substrates with the lattice mismatch in the range of -4 〜1%. For the n=2 thin films, the curie temperature decreased very sharply with a decrease of the out-of plane lattice parameters, which results in the enhancement of the MR effect. These results are interpreted in terms of the strain effect induced by the lattice mismatch.The junctions are fabricated using the perovskite manganite (n=∞) and Fe (or Co). These results suggest that the spin polarization of tunneling electrons in these junctions is highly dependent on the electronic structure of the barrier/Fe (or Co) interface.

研究了钙钛矿系列LaィイD2n-nxィエD2CaィイD21+nxィエD2MnィイD2nィエD2ィイD23+1ィエD2(n=2，3，∞)的巨磁阻铁磁体的电磁性能。对具有固定载流子浓度(x=0.3)的外延a轴薄膜样品的输运性质的结果表明，层数的减少导致各种特征的系统变化。其中包括电阻率的增加，对应于金属-绝缘体转变的电阻率峰值温度TCィイD1pィエd1的降低，在tcィイd1pィエd1附近的最大mR的增加，以及低温本征mR的增加。为了解释这些特征随MnOィイd12ィエd1层的数目的变化，有必要同时考虑c轴转移相互作用和二维自旋涨落。研究了LaィイD2n-nxィエD2CaィイD21+nxィエD2MnィイD2nィエD2OィイD23n+1ィエD2的晶格效应。在晶格失配范围为-4~1%的不同衬底上生长了∞薄膜(n=2)，研究了其晶格效应。对于n=2薄膜，随着离面晶格参数的减小，居里温度急剧下降，导致磁流变效应增强。这些结果可以用晶格失配引起的应变效应来解释。用钙钛矿型锰氧化物(n=∞)和Fe(或Co)制备了结。这些结果表明，隧道电子在这些结中的自旋极化高度依赖于势垒/Fe(或Co)界面的电子结构。

项目成果

Jun Hayakawa et al.: "Strain Effect in La_<1-x>Ca_xMnO_3 Thin Films"Journal of Magnetic Society of Japan. 23. 102-104 (1999)

Jun Hayakawa等人：“La_<1-x>Ca_xMnO_3薄膜中的应变效应”日本磁学会会刊。

M. Arita et al.: "Transmission Electron Microscopy of La_<0.7>Ca_<0.3>MnO_3 CMR Thin Films"Japanese Society of Electron Microscopy. 48. 381-385 (1999)

M. Arita等人：“La_<0.7>Ca_<0.3>MnO_3 CMR薄膜的透射电子显微镜”日本电子显微镜学会。

H. Asano, et al.: "Magnetotransport in Thin Films of La_<n-nx>Ca_<1+nx>Mn_nO_<3n+1>(n=2,3,and ∞)"Material Research Society Symposium. 494. 131-136 (1998)

H. Asano 等人：“La_<n-nx>Ca_<1+nx>Mn_nO_<3n+1>（n=2,3 和 ∞）薄膜中的磁输运”材料研究学会研讨会 494。 131-136 (1998)

H. Asano, et al.: "Pulsed-laser deposited Sr_2FeMoO_6 Thin Films : Positive and Negative Magnetoresistance Regimes"Applied Physics Letters. 74. 3696-3698 (1999)

H. Asano 等人：“脉冲激光沉积的 Sr_2FeMoO_6 薄膜：正磁阻和负磁阻状态”应用物理快报。

Jun Hayakawa et al.: "Strain effect in La_<n-nx>Ca_<1+nx>Mn_nO_<3n+1> thin films" Journal of Magnetic Society of Japan. 23(In press). (1999)

Jun Hayakawa 等人：“La_<n-nx>Ca_<1 nx>Mn_nO_<3n 1> 薄膜中的应变效应”日本磁学会杂志。