EVOLUTION OF F ELECTRON STATE DUE TO THE MANY BODY EFFECT ARISING FROM SPIN AND ORBITAL DEGRESS OF FREEDOM-EXPERIMENTAL STUDIES ON ALLOYS OF THE F ELECTRON COMPOUNDS

1.我们对合金化合物Ce_xLa_&lt；1-x&gt；B6和Pr_xLa_&lt；1-x&gt；136进行了dHvA效应和电阻率测量。LaI…136的主费米面随x变化很大，有效质量随x近似线性增加。当基态为有序态时，有效质量随场的减小而显著增大，但在低场时几乎保持不变；当基态为无序态时，有效质量发散，导电电子的非费米液体行为出现。当x较小时，上下自旋传导电子的有效质量几乎相同，但当x较大时，两者的有效质量相差很大。另一方面，Pr_xLa_(1-x)Gt；B_6的费米面和有效质量随x变化不大，没有发现有效质量和输运性质的反常行为。2.对于CeU_2(Si_xLa_t；1-x&gt；Ge_x)_2，我们通过磁测量确定了其磁相图，并进行了…分析更多的是dHvA效应研究。我们在x从0到1的不同样品中成功地观察到了dHvA效应。从这些测量中，我们揭示了磁相图、量子临界点、变磁跃迁与电子态，特别是f电子的局域游荡态之间的关系。3.我们还成功地观察到了合金化合物Pr_&lt；1-x&gt；La_xPb3以及其他强相关f电子化合物中的dHvA效应。4.我们将与dHvA效应测量相适应的活塞筒的最大压力提高到了3 Gpa以上。由于这一改进，我们阐明了压致超导体CeIn_3的电子结构随压力的变化和弱铁磁体ZrZn_2的磁态随压力的变化，以及具有无反转对称性的压致超导体CeRhSi_3和压致铁磁超导体UGe_2的电子和超导性质。

1.We have performed the dHvA effect and resistivity measurements on the alloy compounds Ce_xLa_<1-x>B6 and Pr_xLa_<1-x>136 and have found the followings. The main Fermi surface of Ce.Lai..136 changes considerably with x and the effective mass increases almost linearly with x. The effective mass increases markedly with decreasing field but becomes nearly constant at low fields when the ground states are ordered states, while it diverges and then non-Fermi liquid behavior of the conduction electron appears when the ground state is the disordered state. The effective masses of the up and down spin conduction electrons are nearly the same when x is small but differ largely when x is large. On the other hand, the Fermi surface and the effective mass of Pr_xLa_<1-x>B_6 does not change largely with x and no anomalous behaviors of effective mass and transport properties are found.2.For CeRu_2(Si_<1-x>Ge_x)_2 we have determined the magnetic phase diagram by magnetic measurements and also perfor … More med the dHvA effect study. We have successfully observed the dHvA effect in the samples with various x ranging from 0 to 1. From these measurements we have uncovered the relationship among the magnetic phase diagram, quantum critical point, metamagnetic transition and the electronic state, particularly localized-itinerant state of the f electron.3.We have also observed successfully the dHvA effect in the alloy compound Pr_<1-x>La_xPb_3 as well as other strongly correlated f electron compounds.4.We have increased the maximum pressure of the piston cylinder cell which is compatible with the dHvA effect measurements up to above 3GPa. Owing to this improvement we have clarified the electronic structure change with pressure of the pressure induced superconductor CeIn_3 and the variation of the magnetic state with pressure of the weak ferromagnet ZrZn_2 as well as the electronic and superconducting properties of the pressure induced superconductor CeRhSi_3 with no-inversion symmetry and of the pressure induced ferromagnetic superconductor UGe_2. Less