Research of quantum multi-electron states in Yb-based compounds

镱基化合物量子多电子态研究

基本信息

批准号：
16340105
负责人：
WADA Shinji
金额：
$ 10.43万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

In Yb-based compounds, the f electron level is rather less broadened than in the Ce case, that results in some exotic phenomena such as valence fluctuations, large orbital degeneracy, and higher-order multipolar ordering which can not be understood by simple electron-hole analogy. We have carried out experimental studies on Yb-based 114 series compounds and related ones, and successfully deduced important information described below to understand the underlying issues.Field-tuning of Yb-based antiferromagnetic compounds to the quantum critical point(1) The electrical resisitivity and NMR measurements on the heavy fermion compound YbAuCu4 provided evidence that the system can be driven from the originally antiferromagnetically ordered state to a nonmagnetic Fermi liquid state through the quantum critical point in fields close to 〜13kOe through. Temperature and field participating in the quantum critical phenomena are about one order higher in energy than those of YbRh2Si2 that has been … More intensively studied as only one non-Fermi liquid material among the Yb-based compounds.(2) Heavy fermion filled-skutterudite compound YbFe4P12 has the quantum critical point in field less than 1 kOe, and exhibits the non-Fermi liquid-like behavior at rather high temperatures below〜10K.Evolution of electronic states associated with approaching the quantum critical point by applying external pressure(3) The first-order valence transition of YbInCu4 is completely suppressed with applying pressures above 2.4GPa, and the compound was found to transform into a ferromagnetically ordered ground state below 2.5 K. A temperature-pressure phase diagram for pressures up to 27GPa was established.(4) Heavy fermion compound YbCu5 is shown to have the quantum critical point near 5GPa, and NMR measurements up to 2.5GPa exhibited that the localized properties of f electrons increases with pressure.Experimental evidence for multipolar orderings(5) The mixed-typed quadrupolar ordering in YbSb with Kramers doublet CEF ground state was evidenced by measuring the isotope effect on the Sb NMR linewidth.(6) TmTe is shown to exhibit a multipolar (probably octupolar) ordering at 〜20K, in addition to the well know quadrupolar order at 1.6K. Less

在 Yb 基化合物中，f 电子能级比 Ce 情况下的展宽要小得多，这会导致一些奇特的现象，例如价态波动、大轨道简并性和高阶多极有序性，这些现象不能通过简单的电子-我们对镱基114系列化合物及相关化合物进行了实验研究，并成功推导了以下重要信息以了解根本问题。镱基反铁磁化合物的场调谐到量子临界点(1) 对重费米子化合物 YbAuCu4 的电阻率和核磁共振测量提供了证据，表明系统可以通过接近 ~ 场的量子临界点从最初的反铁磁有序态驱动到非磁性费米液态。参与量子临界现象的温度和场的能量大约比 YbRh2Si2 高一个数量级，YbRh2Si2 已被广泛研究为唯一的一个。镱基化合物中的非费米液体材料。(2)重费米子填充方钴矿化合物YbFe4P12在场中的量子临界点小于1 kOe，并且在以下相当高的温度下表现出类非费米液体行为〜 10K.施加外部压力接近量子临界点时电子态的演化(3) YbInCu4的一级价态跃迁在施加以上压力时被完全抑制2.4GPa，并且在低于2.5 K时发现该化合物转变为铁磁有序基态。建立了压力高达27GPa的温度-压力相图。(4)重费米子化合物YbCu5在附近具有量子临界点5GPa 和高达 2.5GPa 的 NMR 测量表明 f 电子的局域特性随着压力的增加而增加。多极的实验证据排序(5) 通过测量同位素对 Sb NMR 线宽的影响，证明了具有 Kramers 双峰 CEF 基态的 YbSb 中的混合型四极排序。(6) TmTe 在 ~20K 时表现出多极（可能是八极）排序，除了众所周知的 1.6K 以下的四极阶。