ルテニウム系ペロブスカイト型酸化物の異常な遍歴電子物性

钌基钙钛矿氧化物不寻常的流动电子特性

• 批准号: 09440241
• 负责人: YOSHIMURA Kazuyoshi
• 金额: $ 5.38万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09440241/
• 关键词: Nuclear Magnetic Resonance; Invar Effect; Itinerant Electron Magnetism; Strongly Correlation; SrRuO_3; CaRuO_3

Recently, the 4d transition metal (especially, Ru) oxide systems with perovskite type structure have been extensively investigated. Among them, in this research work, we focus on the Sr_<1-x>Ca_xRuO_3 system, which shows metallic conductivity. The purpose of this work is to elucidate the mechanism of magnetic properties of this metallic system from the standing point of spin fluctuations. In order to get systematic and microscopic understandings we mainly conducted the nuclear magnetic resonances (NMR) of Ru and Oxygen. Nuclei, former of which belongs to the magnetic atom itself and the latter locates in the chemical bonds between Ru atoms. The specific heat and high-field magnetization have also been measured and analyzed from a view point of itinerant magnetism.First, from the results of the high-field magnetization measurements up to 40 T, a typical property of itinerant system was observed : the magnetization does not saturate even at 40 T for all the sample of this system. The res … More ults of the specific heat experiments revealed characteristic property of strongly correlated electron system : the electronic specific heat coefficient gamma is largely enhanced by exchange interaction and increases with increasing x from 0, and takes a maximum value of about 100 mJ/K^2mol at x=0.8. These values of gamma and their temperature variations were found to be understood by the self-consistent renormalization (SCR) theory of spin fluctuations for itinerant-electron ferromagnetic system. As a result of their analyses, the spin fluctuation parameters T_0 and TA can be obtained for every x. Here, T_0 is the parameter indicating the energy width of spin-fluctuation spectrum, and T_A the parameter which gives the wave number dependence of spin-fluctuation spectrum.From 170 NMR the spin-lattice relaxation rates 1/T_1 for x=l .0 and 0.6 were found to be well understood by the SCR.However, 1/T_1 was not explained by the SCR theory, leading to that SrRuO_3 locates in the intermediate regime between weak itinerant and localized moment ferromagnetic systems, which is consistent with the discovery of the invar effect in this compound. Furthermore, these results indicate that CaRuO_3, which loses the long-range magnetic order, can be classified not as the antiferromagnetic compound but as the nearly ferromagnetic compound. Therefore, we conclude every result can be understood as itinerant ferromagnetic properties and there is evidence for the existence of antiferromagnetic interaction. Ru NMR is now in progress and can be expected to give us a direct information of magnetic atom itself. Less

最近，已经广泛研究了具有钙钛矿类型结构的4D过渡金属（尤其是RU）氧化物系统。其中，在这项研究工作中，我们专注于SR_ <1-X> CA_XRUO_3系统，该系统显示了金属电导率。这项工作的目的是从自旋波动的站立点阐明该金属系统的磁性特性机理。为了获得系统的理解，我们主要进行了RU和氧的核磁共振（NMR）。原子核，前者属于磁原子本身，后来位于Ru原子之间的化学键中。还从巡回磁性的角度测量和分析了特定的热量和高场磁化。首先，从高达40 t的高场磁化测量结果中，观察到静脉系统的典型特性：即使在40 t的40 t中，该系统的所有样品也不会饱和。 RES…更多的特定热实验的ults揭示了密切相关的电子系统的特征特性：电子特异性热核心伽玛在很大程度上通过交换相互作用增强，并随着x从0增加而增加，并且在x = 0.8时的最大值约为100 mj/k^2mol。发现这些伽玛的值及其温度变化是通过自谐的重新归一化（SCR）的自旋波动理论来理解的。由于它们的分析，可以为每个X获得自旋波动参数T_0和TA。在这里，t_0是指示自旋 - 透射光谱的能量宽度的参数，t_a的参数给出了旋转 - 触发频谱的波数依赖性。从170 nmr到x = l .0和0.6的旋转静止放松率1/t_1在scr.1中被认为是1/t_1/t _ 1/t _ 1/t _ 1/t _ 1/t _ 1/T_位于弱迭代和局部矩铁磁系统之间的中间状态，这与在该化合物中发现oud效应的效果一致。此外，这些结果表明失去远距离磁性的Caruo_3可以分类为反铁磁化合物，而是将其分类为近铁磁化合物。因此，我们包括每个结果，都可以理解为流动的铁磁特性，并且有证据表明存在抗铁磁相互作用。 Ru NMR现在正在进行中，可以预期将为我们提供磁原子本身的直接信息。较少的

项目成果

H.Kageyama: "Synthesis and magnetic properties of new series of one-dimensional oxides Ca_3Co_<1+X>B_<1-X>O_6(B=Ir, Ru)" J.Solid State Chem.140. 14-19 (1998)

H.Kageyama：“新型一维氧化物系列Ca_3Co_<1 X>B_<1-X>O_6(B=Ir, Ru)的合成和磁性能”J.Solid State Chem.140。

H.Kageyamaa: "ESR study of Fe-doped Ca_3Co_2O_6 : Isolated spin state of Fe^<3+> and anomalous D parameter caused by exchange interaction" Phys.Rev.B. 58 (17). 11150-11152 (1998)

H.Kageyamaa：“Fe 掺杂 Ca_3Co_2O_6 的 ESR 研究：Fe^<3> 的孤立自旋态和交换相互作用引起的异常 D 参数” Phys.Rev.B。

H.Kageyama: "Synthesis and magnetic properties of new series of one-dimensional oxides Ca_3Co_<1+x>B_<1-x>O_6 (B=Ir,Ru)" J.Solid State Chem.140. 14-19 (1998)

H.Kageyama：“新系列一维氧化物Ca_3Co_<1 x>B_<1-x>O_6 (B=Ir,Ru)的合成和磁性能”J.Solid State Chem.140。

T.Kiyama: "Specific Heat of (Sr-Ca) RuO_3" J.Phys.Soc.Jpn.67 (1). 307-311 (1998)

T.Kiyama：“(Sr-Ca) RuO_3 的比热”J.Phys.Soc.Jpn.67 (1)。

K.Yoshimura: "Characterizations of Heavy-Fermion Cubic YbCu_5 and Intermediate-Valence Hexagonal YbCu_5" Physics of Strongly Correlated Electron Systemes. JJAP Series 11. 242-244 (1999)

K.Yoshimura：“重费米子立方 YbCu_5 和中价六方 YbCu_5 的表征”强关联电子系统物理学。