Anisotropic Hybridization in the Heavy-Electron Systems

重电子系统中的各向异性杂化

• 批准号: 03452044
• 负责人: FUJII Hironobu
• 金额: $ 4.86万
• 依托单位: HIROSHIMA 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: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-03452044/
• 关键词: Hybridization; Kondo Lattice; Cerium Compound; Heavy Fermion; Valence Fluctuation; Metal-Insulator Transition; Single Crystal; Magnetism; 価数揺動; 電気低抗; 熱電能; Hybridization; Kondo Lattice; Cerium Compound; Heavy Fermion; Valence Fluctuation; Metal-Insulator Transition; Single Crystal; Magnetism; 価数揺動; 電気低抗; 熱電能

In the course of our searching study for new heavy-electron systems, we have found that several cerium and uranium intermetallic compounds display some interesting physical properties as Kondo-lattice groundstates, depending on the degree of hybridizations of f-electrons with the ligand s, p or d-electron states near the Fermi-level. Under consideration that such unusual physical properties should originate in anisotropic hybridization effects between the f and p or d-electrons, we planned to make single crystals of newly found systems and to perform their systematic investigations. The results obtained are summarized as follow: (1) An anisotropic gap in CeNiSn opens in the heavy-quasiparticle bands as temperature is reduced below 6K. The highly anisotropic behavior of susceptibility chi, electrical resistivity rho, thermoelectric power S and thermal expansion aipha reflects the strongly anisotropic hybridization of the Ce 4f-states with the Sn 5p- and Ni 3d-electron states in the epsi … More lon-TiNiSi orthorhombic structure. An anisotropic gap suppression is also observed under high-magnetic fields (H < 13T) along the a-axis and high pressures above 20 kbars. (2) For the heavy-fermions CePdIn and UPdIn with the same hexagonal ZrNiAl-type structure, chi and rho along the a and c-axes are significantly anisotropic and exhibit a marked contrast; chi_a*chi_c and rho_a>rho_c for CePdIn,and chi_a<<chi_c and rho_a<rho_c for UPdIn, respectively. For the comparison of the anisotropy in chi calculated by the bare CEF effects, the hybridization-induced anisotropy in CePdIn cancels in part the single-ion anisotropy of the CEF effects and vice versa in UPdIn. (3) The semiconducting to metal transition in UNiSn has been studied using highquality single phased samples prepared by annealing process at 800ﾟC for 90 days. The metallic state below 43K is stabilized by a type-I antiferromagnetic ordering of the U moments (like inverse Mott-transition). These phenomena could be explained by considering anisotropic hybridizaitons between U 5f-electron and Sn 5p-electron states. Less

在我们针对新的重型电子系统的搜索研究过程中，我们发现，几种葡萄和铀间的金属层化合物显示出一些有趣的物理特性，例如近调晶状体，取决于Fermi-Level附近的配体S，P或D-电子状态的F-电子杂交程度。考虑到这种不寻常的物理特性应起源于F和P或D电子之间各向异性杂交效应，我们计划制造新发现的系统的单晶并进行系统投资。所获得的结果总结如下：（1）cenisn中的各向异性差距在重质量带中打开，因为温度降低了6k以下。易感性CHI，电阻RHO，热电功率S和热膨胀AIPHA的高度各向异性行为反映了CE 4F状态的强烈各向异性杂交，而SN 5P和NI 3D-ELECTRON态在EPSI中……更多的en lon-Tinisi或Tinisi或Tinisi或更多的结构。在高磁场（H <13T）下，沿着A轴和高于20 kbar的高压在高磁场（H <13T）下也观察到各向异性间隙抑制。 （2）对于具有相同的六角形Zrnial型结构的重物cepdin和Updin，沿A和C轴沿着A和C轴的Rho具有明显各向异性，并且暴露了明显的对比度； chi_a*chi_c and rho_a> rho_c for cepdin，chi_a << chi_c和rho_a <rho_a <rho_c <rho_c分别用于updin。为了比较通过裸露CEF效应计算的CHI中的各向异性，杂交诱导的CEPDIN中的各向异性取消了CEF效应的单离子各向异性，而VICE VICE VESA在Updin中。 （3）使用高质量的单杆样品在800°C下制备了90天的高质量单杆样品。 43K以下的金属状态通过U矩的I型抗磁磁有序稳定（例如反向Mott-Transition）。这些现象可以通过考虑U 5F电子和SN 5P电子状态之间的各向异性杂交子来解释。较少的