Investigation of Magnetotransport Phenomena in Half Metallic CrO2

半金属 CrO2 磁输运现象的研究

• 批准号: 10650032
• 负责人: SUZUKI Katsuhiko
• 金额: $ 2.24万
• 依托单位: Miyagi National College of Technology
• 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-10650032/
• 关键词: Half Metal; X-Ray Diffraction; Thermal Treatment; Co-Tunneling; Magnetoresistance; CVD; Quantized Energy Level; Distortion of Crystal Structure; CrO_2; 電気抵抗; 磁気抵抗; 強い電子相関効果; 単結晶

(1) It was found that the CrO2 film is selectively deposited onto the patterned TiO2 film by the thermal oxidation of the Ti film on the glass substrates in terms of CVD method. The tunnel junction was made using the technique. Although the value of tunnel resistance was adequate, the TMR properties did not show the good data. The properties may be improved by making the interface between the CrO2 film and insulator smooth.(2) The resistivity and magnetoresistance of the CrO2 film with only (100) texture on the ZrO2 substrate were measured in the wide temperature range up to 10T.The shape of the temperature dependence of resistivity can be interpreted by the description of the half metal and the relation of the values of the coefficient of T^2 dependence and electronic specific heat suggested the CrO2 belongs to the group of the heavy fermion. The value of the parameters obtained by the analysis of the data of the magnetoresistance contain the information on the mean free path and they … More suddenly increased below about 5K, which shows the lack of spin flip scattering process by magnon excitation because of the half metal.(3) The magnitude of the negative magnetoresistance of (100) CrO2 film on TiO2/Si (111) with (110) orientation was larger than that of (100) film on ZrO2 substrate.(4) By the annealing at 473K, the magnitude of the negative magnetoresistance (MR) of the CrO2 film on TiO2/glass became large above about 20K, while the magnitude small below about 20K.The lattice spacing of a-axis was extented by the annealing at 473K.The band calculation and WKB approximation suggest that the magnitude of MR becomes by this extension.(5) The staircase pattern in magnetic field dependence in magnetoresistance was found. The step height of the staircase was constant under a constant current and reciprocal to the current, which means that the steps change at each the constant voltage interval. These phenomena can be interpreted by co-tunneling of the multi-tunnel junctions contained in the films. Less

(1)发现采用CVD法，通过热氧化玻璃基板上的Ti膜，在图案化的TiO2膜上选择性地沉积CrO2膜，并利用该技术制成了隧道结。电阻足够，TMR性能没有显示出良好的数据，可以通过使CrO2薄膜与绝缘体之间的界面光滑来改善性能。(2)电阻率和磁阻。在高达 10T 的宽温度范围内测量了 ZrO2 基底上仅具有 (100) 织构的 CrO2 薄膜。电阻率随温度变化的形状可以通过半金属的描述和值的关系来解释T^2相关系数和电子比热表明CrO2属于重费米子族。通过磁阻数据分析得到的参数值包含了平均自由程的信息。并且它们在大约5K以下突然增加，这表明由于半金属的原因，缺乏磁振子激发的自旋翻转散射过程。（3）TiO2/Si（111）上的（100）CrO2薄膜的负磁阻大小(110)取向薄膜在ZrO2衬底上的取向大于(100)取向薄膜。 (4)通过473K退火，负磁阻的大小TiO2/玻璃上的CrO2薄膜的(MR)在约20K以上变大，而在约20K以下幅度变小。a轴晶格间距因473K退火而扩大。能带计算和WKB近似表明幅度(5)发现了磁阻中磁场依赖性的阶梯图案，在恒定电流下，阶梯的阶梯高度是恒定的。电流的倒数，这意味着步长在每个恒定电压间隔处发生变化，这些现象可以通过薄膜中包含的多隧道结的共隧道来解释。

项目成果

K.Suzuki and P.M.Tedrow: "Longitudinal Magnetoresistance of CrO_2 Thin Films" Applied Physics Letters. Vol.74,No.3. 428-429 (1999)

K.Suzuki 和 P.M.Tedrow：“CrO_2 薄膜的纵向磁阻”应用物理快报。

K.Suzuki and P.M.Tedrow: "Longitudinal Magneto resistance of CrO_2 Thin Films"Applied Physics Letters. 74. 428-429 (1999)

K.Suzuki 和 P.M.Tedrow：“CrO_2 薄膜的纵向磁阻”应用物理快报。

K.Suzuki and P.M.Tedrow: "Selective Deposition of CrO2 Film on Glass Substrates"Solid State Commun.. 107. 583-585 (1998)

K.Suzuki 和 P.M.Tedrow：“在玻璃基板上选择性沉积 CrO2 薄膜”Solid State Commun. 107. 583-585 (1998)

K.Suzuki and P.M.Tedrow: "Resistivity and Magnetotransport in CrO_2 Films" Physical Review B. Vol.58,No.17. 11597-11602 (1998)

K.Suzuki 和 P.M.Tedrow：“CrO_2 薄膜中的电阻率和磁输运”物理评论 B. 第 58 卷，第 17 期。

K.Suzuki and P.M.Tedrow: "Resistivity and Magnetoresistance in CrO_2 Films"Physical Review. B58. 11597-11602 (1998)

K.Suzuki 和 P.M.Tedrow：“CrO_2 薄膜中的电阻率和磁阻”物理评论。