Electron-Lattice Interaction of Strongly Correlated Electron Systems

稀土和含f电子的铀化合物的强关联电子体系中的磁性指令导致了反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电子系统中的低温现象也起着重要的作用。在这个项目中，我们用超声测量的方法研究了f电子化合物中的电子-晶格相互作用。晶场中4f态的四极矩与晶格系统的耦合引起了弹性常数随温度变化的软化。在本项目中，我们重点研究了致密的Kondo系统Ce_&lt；1-x&Gt；La_xB_6在低温下的四极响应。建立了Ce_&lt；1-x&GT；La_xB_6中近藤单态的实验证据和反铁四元相的反常磁相图。此外，还研究了近藤化合物CePd_2Al_3、超导体UPd_2Al_3和低载流子系统CEAS、CEP。F电子化合物中的声学dHvA效应对于电子-晶格相互作用的数值研究是非常重要的。Kataoka和Goto建立了声学dHvA效应理论，它提供了巡回电子系统的电子-晶格相互作用。利用超导磁体(牛津，14T)，测量了声学dHvA效应CEAS、CEP、CEBI、LAAS、HOB_&lt；12&gT；要了解f电子系统中的电子-晶格相互作用，还需要更详细的研究。

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.