铈基重费米子材料及钌系化合物中的磁性量子相变与非费米液体行为

项目名称： 铈基重费米子材料及钌系化合物中的磁性量子相变与非费米液体行为

项目编号： No.10874146

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 无线电电子学、电信技术

项目作者： 袁辉球

作者单位： 浙江大学

项目金额： 46万元

中文摘要： 零温下磁性材料中的有序/无序磁性量子临界态及相关物理现象由于违背了经典的朗道费米液体理论而受到广泛关注，是凝聚态物理研究的一个重大基础问题。现有的量子相变理论主要包括建立在Landau-Wilson-Ginzburg经典相变理论基础上的Hertz-Millis自旋密度波理论和正在发展的局域量子临界理论。这两种理论似乎适用于不同的关联电子系统，其争论的焦点在于局域电子在量子临界点的属性变化以及表现出的不同标度行为。为了阐明这些重要的物理问题，本课题将重点研究铈基重费米子化合物以及钌系化合物这两类关联电子材料在外加压力和磁场下的量子临界行为。通过dHvA效应以及其它热力学量的测量，研究磁性量子临界点附近可能伴随的费米面拓扑结构的重组以及非费米液体行为。我们将分析不同材料的量子临界态的标度行为，寻找量子临界态的本质特征，探索量子相变与超导的内在联系，为建立统一的量子相变理论提供重要实验依据。

中文关键词： 量子相变；非费米液体；重费米子体系；钌系化合物

英文摘要： The zero-temperature quantum phase transition has attracted considerable attention because of the fascinating physical properties caused by quantum fluctuations. Revealing the nature of quantum criticality remains a fundamental physical problem. Among the current theories of quantum criticality, the debate mainly focuses on the evolution of the localized f/d-electrons and the corresponding scaling behavior at the quantum critical point (QCP). To elucidate these important physical problems, in this project two classes of materials, i.e., the Ce-based heavy fermion compounds (CeRhIn5 and CeCu2Si2) and the ruthenates (Sr,Ca)3Ru2O7, will be investigated under extreme conditions of high pressures and high magnetic fields. By means of dHvA effect and Hall effect measurements in very strong magnetic fields, we are going to study the Fermi surface topology and, therefore, the possible localization/delocalization transition of f electrons at a magnetic field induced quantum critical point. On the other hand, the general scaling behavior at a QCP will be investigated by measuring various thermodynamic and transport properties under high pressure and magnetic fields, with which the magnetic order in the materials mentioned above is expected to be suppressed. This project aims at characterizing the main features of magnetic quantum criticality, revealing the possible relations among quantum criticality, superconductivity and non-Fermi-liquid behavior, and providing necessary experimental evidence for developing a uniform theory of quantum criticality.

英文关键词： Quantum phase transition; non Fermi liquid; heavy fermion; ruthenates