Electron-Lattice Interaction in Strongly Correlated Electron Systems

名为“强关联电子系统的电子-晶格相互作用”的国际科学研究计划已经启动。T.Goto教授和B.Luthi教授分别是日方和德方的首席调查员。日方提议的要点如下：(1)f电子体系的四极-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有趣的问题。在CeU_2Si_22和Ce_xLa_t；L-x&GT；B_6的Kondo单重态体系中，四极响应和Kondo效应之间的竞争以及铀化合物G3基态存在四极Kondo效应的可能性是非常重要的。(2)Luthi小组对重费米诺超导体CeCu_2Si_2和UPT_3的超声研究揭示了反常的磁相图。Fujita等人发现了高T_c超导体La_&lt；2-x&Gt；Sr_xCuO_4中弹性常数与磁场的特殊关系。用超声方法研究了高T_c超导体、重费米子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--声学dHvA效应--是研究电子-晶格相互作用的唯一探针。对低载流子、重费米子、低维有机化合物等各种电子体系的电子-晶格相互作用进行系统的研究具有重要意义。尤其是铜对的微观起源和增强的Gruneisen常数是有趣的课题。(4)吉原的布里渊散射实验现在可以研究低维磁性薄膜、超晶格和各种含有f电子的单晶中的磁振子和声子激发。热膨胀和地压收缩也很重要。

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.