Magnetic Properties of Alloys Having Narrow Bands Near the Fermi Level-Impurity Effects and Magnetic Field Effects.

费米能级附近窄带合金的磁性——杂质效应和磁场效应。

• 批准号: 01460023
• 负责人: MIYAKO Yoshihiko
• 金额: $ 4.16万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1989
• 资助国家: 日本
• 起止时间: 1989 至 1990
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-01460023/
• 关键词: Magnetism; muSR; Quadrupolar order; Rare earth; Actinide; magnetisn; 相移転; 磁気異方性

In the present research, we studied the following systems : (1) 4f-electron compounds such as CeAg and CeB_<6^ﾟ>whose f-electron quadrupole moments and their interactions play dominant role on the magnetic properties (2) heavy electron systems such as UPt_3 and URu_2Si_2 where super conductivity and magnetic ordering coexist each other.For the case (1), we first examined CeAg_<1-X>In_X. It is considered that the quadrupole-quadrupole interactions are responsible for the low temperature structural phase transition in CeAg. By substituting In for Ag in CeAg, the origin of the structural phase transition is considered to change from the quadrupole interactions to 5d-band John-Teller effect and/or softening of the TA_2 phonon mode. It is also considered that the density of state at the Fermi level increases by the In substitution. Thus, magnitude of the magnetic anisotropy appearing upon the structural phase transition is also expected to change with increasing x in CeAg_<1-X>In_X. In orde … More r to clarify this point, we performed the mu^+SR experiment in CeAg_<1-X>In_Xaround the structural phase transition temperature T_<M^+> Althow there are a number of possible mu^+site in the crystal, we analyzed the data assuming 2-sited for mu^+ : the site with a wide internal field distribution that gives a rapid relaxation time, and the site with a narrow field distribution that gives a slow relaxation. For the sample with 3% In, the anisotropy associated with the structural phase transition decreases due to the increase in the density of state at the Fermi level. As the result, the effect on the mu^+ relaxation time is found to be small at T_M, and only the usual critical relaxation that decreases monotorucally towards the ferromagnetc ordering temperature Tc was observed.Another example of the case (1) is CeB_6. This system shows both quadrupole ordering and the antiferromagnetic ordering at T=3, 3K and 2, 3K, respectively. By means of the nonlinear Ac susceptibility measurement, we observed an anomaly in X_2 around the quadrupole ordering temperature.For the case (2), we mainly studied the impurity effect on URu_2Si_2 by substituting Rh for Ru. In this system, a rich phase diagram has been obtained by controlling the Rh-concentration x. Detail of the results will be published soon in several papers. Less

本论文研究了以下体系：（1）4f电子化合物CeAg和CeB_（6^n），它们的f电子四极矩及其相互作用对磁性起主导作用;（2）重电子体系UPt_3和URu_2Si_2，它们的超导性和磁有序性共存<1-X>。CeAg的低温结构相变是由四极-四极相互作用引起的。用In替代CeAg中的Ag后，结构相变的起源由四极相互作用转变为5d带John-Teller效应和/或TA_2声子模的软化。还认为In的替代使费米能级的态密度增加。因此，在结构相变时出现的磁各向异性的大小也预期随着CeAg_ In_X中x的增加而改变<1-X>。依序 ...更多信息 为了阐明这一点，我们在<1-X>结构相变温度T_&lt;M^+&gt;附近进行了CeAg_ In_X中的μ ^+SR实验。虽然在晶体中存在许多可能的μ ^+位置，但我们对数据进行了分析，假设μ ^+为两个位置：具有宽内场分布的位置，给出快速弛豫时间;对于含3% In的样品，由于费米能级处态密度的增加，与结构相变相关的各向异性减小。结果表明，在T_M处，对μ ^+弛豫时间的影响很小，只观察到通常的临界弛豫，它向铁磁有序化温度T_c单调下降。该体系在T= 3.3K和2.3K时分别表现出四极有序和反铁磁有序。通过非线性交流磁化率测量，我们观察到X_2在四极有序温度附近的反常现象。对于情形（2），我们主要研究了Rh取代Ru对URu_2Si_2的杂质效应。在该体系中，通过控制Rh浓度x，得到了富相相图。结果的细节将很快在几篇论文中发表。少

项目成果

H.Amitsuka,T.Sakakibara,and Y.Miyako: "Magnetism of U(Ru_<1ーx>Rh_x)_2Si_2 in the coherent Kondostate" J.Mag.Mag.Mater.90&91. 517-518 (1990)

H.Amitsuka、T.Sakakibara 和 Y.Miyako：“相干 Kondostate 中 U(Ru_<1ーx>Rh_x)_2Si_2 的磁性”J.Mag.Mag.Mater.90&91 (1990)。

Y.Kohori,T.Kohara M.Kyogaku,K.Asayama H.Amitsuka and Y.Miyako: "NMR study of Pt inU(Pt_<1-X>Pd┣D2X┣D2)┣D23┫D2" J.Mag.Mag.Mater. 90&91. 510-512 (1990)

Y.Kohori、T.Kohara M.Kyogaku、K.Asayama H.Amitsuka 和 Y.Miyako：“Pt inU(Pt_<1-X>Pd┣D2X┣D2)┣D23┫D2 的 NMR 研究”J.Mag。材料杂志 90&91。

H.Amitsuka,T.Sakakibara and Y.Miyako: "Magnetism of U(Ru_<1-X>Rh_X)_2Si_2 in the coherent Kondo state" J.Mag.Mater.90&91. 517-518 (1990)

H.Amitsuka、T.Sakakibara 和 Y.Miyako：“相干近藤态下 U(Ru_<1-X>Rh_X)_2Si_2 的磁性” J.Mag.Mater.90

Y. Kohori, T. Kohara, M. Kyogaku, K. Asayama, H. Amitsuka and Y. Miyako: "NMR study of Pt in U(Pt_<1-X>Pd_X)_3" J. Mag. Mag. Mater. 90&91. 510-512 (1990)

Y. Kohori、T. Kohara、M. Kyogaku、K. Asayama、H. Amitsuka 和 Y. Miyako：“U(Pt_<1-X>Pd_X)_3 中 Pt 的 NMR 研究”J. Mag。

Y. Miyako, K. Hyomi, H. Amitsuka, and T. Taniguchi: "The Effect of Magnetic Anisotropy on Positive Muon Spin Relaxation in CeAg_<1-X>In_X" J. Phys. Soc. Jpn.

Y. Miyako、K. Hyomi、H. Amitsuka 和 T. Taniguchi：“磁各向异性对 CeAg_<1-X>In_X 中正 μ 子自旋弛豫的影响”J. Phys。