Structure and Physical Properties New Heavy Fermion Systems -Amorphous Cerium Alloys-

结构和物理性能新型重费米子系统-非晶态铈合金-

• 批准号: 03452029
• 负责人: SUMIYAMA Kenji
• 金额: $ 4.22万
• 依托单位: Tohoku 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-03452029/
• 关键词: heavy fermion system; cerium-copper alloy; cerium-silicon alloy; cerium-ruthenium alloy; low temperature specific heat; magnetic susceptibility; electrical resistivity; amorphous; 重い電子系; セリウムー銅合金; セリウムールテニウム合金; 電気低抗; heavy fermion system; cerium-copper alloy; cerium-silicon alloy; cerium-ruthenium alloy; low temperature specific heat; magnetic susceptibility; electrical resistivity; amorphous; 重い電子系; セリウムー銅合金; セリウムールテニウム合金; 電気低抗

In Ce-based alloys, the f electrons mix with s and p electrons and their strong correlation make the effective mass of conduction electrons very heavy. In this project, we have studied X-ray diffraction, lowtemperature specific heat, magnetic susceptibility, electrical resistivity, magnetoresistance, thermoelectric power and X-ray photo electron spectroscopy of amorphous (a-) Ce alloys. We obtained the following results. 1) The electronic specific heat coefficient, gamma, is much larger in a-Ce-Cu, a-Ce-Si and a-Ce-Ru alloys than in a-La alloys, demonstrating the importance of 4f electrons in the heavy electron systems. 2) In the a-Ce-Cu alloys, the random structure disturb the electron correlation to result in an impurity or incoherent Kondo (IK) state. 3) In the a-Ce-Si alloys, a rather strong Kondo effect displays a signature of a coherent Kondo (CK) state, but still an IK state is realized due to their random structures. 4) In the a-Ce-Ru alloys, the mixing of 4f and conduction electrons and their correlation are so strong that a CK state and a superconducting state are realized. 5) The interatomic distance between Ce atoms decreases with increasing Ce concentration, while those for Ce-Cu, Ce-Si and Ce-Ru are insensitive to the alloy concentrations. The coordination numbers around Ce atoms are smaller in the amorphous states than in their crystalline counterparts. 6) Valence and core electron spectra indicate that the mixing of 4f and conduction electrons is enhanced in order, the a-Ce-Cu, a-Ce-Si and a-Ce-Ru alloys. 7) The physical properties of the a-Ce-Ni alloys produced by vapor deposition and liquid quenching are quite different, suggesting that the degree of randomness depends on preparation methods.

在基于CE的合金中，F电子与S和P电子混合及其强相关性使有效的传导电子质量非常重。在这个项目中，我们研究了X射线衍射，低温特异性热，磁敏感性，电阻率，磁磁性，热电功率和X射线光电电子光谱（A-）CE合金。我们获得了以下结果。 1）电子特异性热系数伽马在A-CE-CU，A-CE-SI和A-CE-RU合金中要比A-LA合金中大得多，这表明4F电子在重电子系统中的重要性。 2）在A-CE-CU合金中，随机结构会干扰电子相关性，从而导致杂质或不连贯的昆多（IK）状态。 3）在A-CE-SI合金中，相当强的近关系效应显示了连贯的昆多（CK）状态的签名，但由于其随机结构，IK状态仍然可以实现。 4）在A-CE-RU合金中，4F和传导电子的混合及其相关性非常强，以至于实现了CK态和超导状态。 5）CE原子之间的原子间距离随着CE浓度的升高而降低，而CE-CU，CE-SI和CE-RU的原子距离对合金浓度不敏感。在无定形状态下，CE原子周围的配位数要小于其晶体。 6）价和核心电子光谱表明4F和传导电子的混合以A-CE-CU，A-CE-SI和A-CE-RU合金的顺序增强。 7）蒸气沉积和液体淬灭产生的A-CE-NI合金的物理特性完全不同，这表明随机性程度取决于制备方法。