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Fermi Surfaces of the Heavy-Ferimion Superconductor near a Quantum Critical Point

量子临界点附近重费里米子超导体的费米面

基本信息

批准号：
15540337
负责人：
OHARA Shigeo
金额：
$ 2.18万
依托单位：
Department of Engineering Physics, Electronics and Mechanics, Graduate School of Engineering, Nagoya Institute 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：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

The purpose of this study is to examine the heavy-fermion superconductivity state in the vicinity of quantum critical point(QCP) from the standpoint of the control of the hybridization between an almost localized 4f-electrons and band electrons by a pressure. We have established the conditions of the single crystal growth by a flux method for a heavy-fermion superconductor Ce_2CoIn_8 and antiferromagnet Ce_2RhIn_8. We have measured a pressure dependence of magnetization, electrical resistivity, Hall effect and transverse magnetoresistance for Ce2CoIn_8 and Ce2RhIn_8 over the temperature range from 0.4 to 300 K. The non-Fermi liquid behavior in Ce_2CoIn_8 is enhanced by a applied pressure. The electronic characters of Ce_2RhIn_8 above 2 GPa is very similar to that for heavy-fermion superconductor Ce_2CoIn_8 at ambient pressure. At low temperature region, T<2 K, the sample dependencies for electrical properties were observed for the both materials. These behaviors may be due to microscopic structural imperfections. Higher quality single crystal is required to study the Fermi surface features of Ce_2MIn_8 system. A study was also made of compound formation in the ternary systems Ce-Rh-Ga with the objective of finding a new heavy-fermion superconductor. We succeeded in growing the single crystals of CeRh_2Ga and YbRh_2Ga by the flux methods. CeRh_2Ga exhibits non-Fermi liquid behavior at low temperatures. We speculated that the NFL behavior observed in CeRh_2Ga may be attributed to the existence of a Griffiths phase in the vicinity of a QCP. YbRh_2Ga is a typical mixed-valent system with a magnetically non-ordered ground state.

本文从压力控制几乎局域化的4f电子与能带电子杂化的角度出发，研究了重费米子在量子临界点（QCP）附近的超导态。用通量法建立了重费米子超导体Ce_2CoIn_8和反铁磁体Ce_2RhIn_8单晶生长的条件。我们测量了Ce2CoIn_8和Ce2RhIn_8在0.4至300 K温度范围内磁化强度、电阻率、霍尔效应和横向磁阻的压力依赖性。Ce_2CoIn_8中的非费米液体行为通过施加压力得到增强。Ce_2RhIn_8在2gpa以上的电子特性与重费米子超导体Ce_2CoIn_8在常压下的电子特性非常相似。在T<2 K的低温区，观察到两种材料的电学性能的样品依赖性。这些行为可能是由于微观结构缺陷造成的。研究Ce_2MIn_8体系的费米表面特征需要更高质量的单晶。为了寻找新的重费米子超导体，还研究了Ce-Rh-Ga三元体系中的化合物形成。我们成功地用通量法生长出了CeRh_2Ga和YbRh_2Ga单晶。CeRh_2Ga在低温下表现出非费米液体行为。我们推测，在CeRh_2Ga中观察到的NFL行为可能归因于在QCP附近存在Griffiths相。YbRh_2Ga是一个具有磁性无序基态的典型混价体系。