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Study of the formation of Magnetic Polaron Lattice in Low-Carrier strongly Correlated Systems

低载流子强相关系统中磁极化子晶格的形成研究

基本信息

批准号：
06452050
负责人：
KOHGI Masahumi
金额：
$ 5.57万
依托单位：
Tokyo Metropolitan University (1995)Tohoku University (1994)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

The purpose of this project is to study the unusual properties of the low carrier systems CeP and Yb_4As_3 by means of neutron scattering. The results are as follows :1.CePCeP shows unusual magnetic phase diagrams under magnetic field as well as under high pressure. It shows also typical dense-Kondo-effect like transport anomalies. Our neutron scattering studies established the magnetic phase diagrams for the magnetic field below about 6 T and for the pressure below about 2 GPa. The obtained magnetic phase diagrams are quite novel and unique. In order to explain the phase diagrams, it is necessary to take into account the fact of the low carrier density in this system. The magnetic polaron model gives the most plausible picture to understand the system.2.Yb_4As_3Yb_4As_3 undergoes structural phase transition at about 290K,which was claimed to be that of a charge ordering. The compound shows also heavy electron anomalies at the low temperatures in spite of its extremely low carrier density of the order of 10^<-3> per formula. Our polarized neutron study proved directly the ordering of Yb^<2+> and Yb^<3+> in this material at low temperatures. The inelastic neutron scattering studies revealed the existence of spin excitations typical of a one-dimensional antiferromagnet. They are ascribed to the one-dimensional configuration of the Yb^<3+> ions caused by the charge ordering. There is also anomalous magnetic response other than the one-dimensional spin excitations. These facts indicate that the heavy electron anomalies in this system are strongly related with the Mott-transition-type change of the electronic state caused by the charge ordering.

本项目的目的是用中子散射方法研究低载流子系统CeP和Yb_4As_3的反常性质。主要研究结果如下：1.CePCeP在磁场和高压下都表现出反常的磁相图。它还表现出典型的密集近藤效应输运异常。我们的中子散射研究建立了低于约6T的磁场和低于约2 Gpa的压力的磁相图。得到的磁相图非常新颖和独特。为了解释相图，有必要考虑该系统中低载流子密度的事实。磁极化子模型给出了最合理的解释。2.Yb_4As_3Yb_4As_3在290K左右经历了结构相变，这被认为是电荷有序的相变。该化合物在低温下也表现出严重的电子反常，尽管它的载流子密度极低，每个公式约为10^&lt；-3。我们的极化中子研究直接证明了这种材料在低温下Yb^&lt；2+&gt；和Yb^&lt；3+&gt；；非弹性中子散射研究揭示了一维反铁磁体典型的自旋激发的存在。它们归因于电荷有序引起的Yb^&lt；3+&gt；离子的一维构型。除了一维自旋激发外，还存在反常的磁响应。这些事实表明，该体系中的重电子反常与电荷有序引起的电子态的Mott跃迁类型变化密切相关。