Electron-Lattice Interaction in Strongly Correlated Electron Systems

“强关联电子系统的电子-晶格相互作用”国际科学研究计划已经启动。T.后藤教授和B.Luthi教授分别是日本和德国方面的首席研究员。日本方面的建议概要如下。（1）由于f电子系统的四极-应变相互作用引起的四极响应和f电子化合物中的四极有序仍然是令人感兴趣的问题。CeRu_2Si_22和Ce_xLa_B_6单重态系统中四极响应与近藤效应的竞争<l-x>以及铀化合物G3基态中四极近藤效应的可能性是非常重要的。（2）Luthi小组对重Fermino超导体CeCu_2Si_2和UPt_3的超声研究揭示了异常的磁相图。Fujita等人在高温超导体La_ Sr_xCuO_4中发现了弹性常数与磁场的特殊关系<2-x>。本文用超声波方法研究了高温超导体、重费米子超导体和有机超导体的电子-晶格相互作用的微观特征。（3）低温下弹性常数的量子振荡，即声学dHvA效应，是研究电子-晶格相互作用的独特探针。系统地研究各种电子系统、低载流子、重费米子、低维有机化合物的电子-晶格相互作用具有重要意义。特别是微观起源的铜对和增强Gruneisen常数是有趣的主题。（4）Yoshihara的布里渊散射实验可以用来研究低维磁性薄膜、超晶格和各种含f电子单晶中的磁振子和声子激发。热膨胀和磁致伸缩也很重要。

The International Scientific Research Program with a title as "Electron-Lattice Interaction of Strongly Correlated Electron Systems"have been started. Prof. T.Goto and Prof. B.Luthi are head investigators of Japan and German sides, respectively. The out line of the propose in Japanese side are as follows.(1)The quadrupolar response due to the quadrupole-strain interaction of the f-electron systems and the quadrupole ordering in f-electron compounds are still interesting problems. The competition between the quadrupole response and the Kondo effect in Kondo singlet systems of CeRu_2Si_22 and Ce^xLa_<l-x>B_6 and the possibility of the quadrupole Kondo effect in G3 ground state of uranium compound are very important.(2)The ultrasonic investigation by Luthi's group on the heavy Fermino superconductor CeCu_2Si_2 and UPt_3 revealed the unusual magnetic phase diagram. Fujita's group found the peculiar magnetic field dependence of the elastic constants in the high Tc superconductor La_<2-x>Sr_xCuO_4. The microscopic character of the electron-lattice interaction of the high Tc, heavy Fermion and organic superconductors are investigated by the ultrasonic method.(3)The quantum oscillation of the elastic constant at low temperatures, acoustic dHvA effect, is a unique probe to examine the electron-lattice interaction. The systematic investigation of the electron-lattice interaction for the various electron systems, low carrier, heavy Fermion, low dimensional organic compounds is important. In particular the microscopic origin of the Copper pair and the enhanced Gruneisen constant are interesting subjects.(4)The Brillouin scattering experiment by Yoshihara is now possible to examine the magnon and phonon excitations in the low dimensional magnetic film, superlattice and various single crystals with f-electrons. The thermal expansion and the manetostriction are also important.