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.

该项目的目的是通过中子散射研究低载体系统CEP和YB_4AS_3的异常特性。结果如下：1.CEPCEP在磁场和高压下显示了异常的磁相图。它还显示了典型的密集效应，例如传输异常。我们的中子散射研究确定了低于6 t的磁场的磁相图和低于2 GPA的压力。获得的磁相图非常新颖且独特。为了解释相图，有必要考虑到该系统中载体密度低的事实。磁极模型给出了最合理的图片来理解系统。2.yb_4as_3yb_4as_3在约290k处进行结构相变，据称是电荷顺序的。尽管其极低的载体密度为每个配方，但该化合物在低温下还显示了沉重的电子异常。我们的极化中子研究直接证明了在低温下该材料中Yb^<2+>和Yb^<3+>的排序。非弹性中子散射研究揭示了一维抗铁磁铁的典型旋转激发存在。它们归因于由电荷排序引起的Yb^<3+离子的一维配置。除了一维自旋激发外，还有异常的磁反应。这些事实表明，该系统中的重电子异常与电荷排序引起的电子状态的莫特转换型变化密切相关。