Study on the Kondo effect of ions with multi-electron occupancy

我们主要研究了以下几个方面的内容：(1)众所周知，杂质安德森模型()作为金属中磁性离子的基本模型，在较大的杂化极限下具有一定的局域费米液体性质。在LAM中是否出现非费米液体(NFL)态？(2)系统1Uxth&lt；1-x&gt；Ru2Si2表现出类似于双通道Kondo模型(TCKM)的NFL态的反常低温行为。但其电阻率随温度的降低而减小。通常情况下，TCKM会增加。这种电阻率可以用IAM来解释吗？(3)已知TCKM在T=0时有一个残余熵1/in。这将在晶体对称性降低的情况下释放，比热将在特征温度处出现峰值。在特征温度附近，磁化率随-In T的增加表现如何？得出以下结论。(1)在杂化过程中，随着晶场的变化，IAM具有包括LFL和NFL性质在内的各种基态。(2)当f^2和f^3之间的价态涨落占主导地位时，我们可以预见到电阻率的下降。(3)特征温度约为晶场分裂的1/10。在那个温度下，磁化率的增加是饱和的。最近测量了UxTh&lt；1-x&gt；Ru_2Si2在强磁场下的比热，没有观察到残余熵。根据本研究的结果，我们可以得出结论，TCKM类型的情景似乎并不简单地适用于该系统。目前正在考虑动态Jahn-Teller效应的作用。

We have studied following subjects.(1) It is known that the impurity Anderson model (TAM), which is a fundamental model for the magnetic ion in metal, has certainly the local Fermi liquid (LFL) properties in large hybridization limit. Does the non-Fermi liquid (NFL) state appear in the LAM? If it does, what kind of transition occurs between the LFL and the NFL states.(2) The system1 U_xTh_<1-x>Ru2Si_2 shows anomalous low temperature behaviors similar to those of the NFL state of the two channel Kondo model (TCKM) type. But its resistivity decreases with decreasing temperature. Usually it is expected to increase in the TCKM.Can this resistivity be explained based on the IAM?(3) It is known that the TCKM has a residual entropy 1/ In at T=0. This will be released under the lowering of the crystal symmetry, and the specific heat will show a peak at a characteristic temperature. How the increase of the magnetic susceptibility with - In T behave near the characteristic temperature?Following conclusions are derived. (1) The IAM has various types of ground states including both LFL and NFL natures depending on the crystalline field when the hybridization is changed. (2) We can expect the decreasing resistivity when the valence fluctuation between f^2 and f^3ates dominates. (3) The characteristic temperature is about 1/10 of the crystalline field splitting. At that temperature the increase of the susceptibility saturates. The residual entropy in the NFL state is still 1/ in 2 even when the parameters are situated very near the transition point to the LFL state.Recently, the specific heat under strong magnetic field is measured for U_xTh_<1-x>Ru_2Si_2, and the residual entropy is not observed. Based on the results of the present study, we may conclude that the scenario of the TCKM type seems not applicable simply to this system. Roles of the dynamical Jahn-Teller effect are now under consideration.