Electron-Lattice Interaction of Strongly Correlated Electron Systems

稀土和铀化合物与f电子的强关联电子系统中的磁指令产生了异常的磁性和超导电性。电子-晶格相互作用对具有轨道角动量的f-电子系统的低温现象也有重要作用。在本计画中，我们利用超音波量测来研究f电子化合物中的电子-晶格相互作用。四极矩的4f-状态在晶场的晶格系统的耦合引起软化的弹性常数的温度依赖性。在本项目中，我们主要研究了致密近藤体系Ce_ La_xB_6在低温下的四极响应<1-x>。建立了Ce_ La_xB_6中Kondo单态<1-x>和反铁四重相反常磁相图的实验证据。此外，还研究了近藤化合物CePd_2Al_3、超导体UPd_2Al_3和低载流子体系CeAs、CeP。f-电子化合物中的声学dHvA效应对于数值研究电子-晶格相互作用是非常重要的。Kataoka和后藤建立了声学dHvA效应理论，该理论提供了巡游电子系统的电子-晶格相互作用。利用本项目的主要成本超导磁体（Oxford，14 T），我们测量了CeAs，CeP，CeBi，LaAs，HoB_2的声学dHvA效应<12>。需要更详细的研究来理解f电子系统中的电子-晶格相互作用。

The magnetic instruction in the strongly correlated electron systems of rare earth and uranium compounds with f-electrons gives rise to unusual magnetism and superconductivity. The electron-lattice interaction has also important role for the low temperature phenomena in the f-electron system with an orbital angular momentum. In this project, we have investigated the electron-lattice interaction in the f-electron compounds by use of the ultrasonic measurements. The coupling of the quadrupole moment of the 4f-state in the crystalline field to the lattice system gives rise to a softening in the temperature dependence of the elastic constant. In the present project, we focused on the quadrupolar response of the dense Kondo system Ce_<1-x>La_xB_6 at low temperatures. The experimental evidence for the Kondo singlet in Ce_<1-x>La_xB_6 and the unusual magnetic phase diagram of an antiferro-quadruple phase have been established. Furthermore, the Kondo compound CePd_2Al_3, superconductor UPd_2Al_3 and low carrier systems CeAs, CeP has been also investigated. The acoustic dHvA effect in the f-electron compounds is very important to examine the electron-lattice interaction numerically. Kataoka and Goto have established the theory of the acoustic dHvA effect, which provides the electron-lattice interaction of the itinerant electron systems. By use of a superconducting magnet (Oxford, 14T), which is dominant cost of this project, we have measured the acoustic dHvA effect CeAs, CeP,CeBi, LaAs, HoB_<12>. More detailed investigation should be required to understand the electron-lattice interaction in the f-electron systems.