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

多电子占据离子的近藤效应研究

基本信息

批准号：
09640451
负责人：
SAKAI Osamu
金额：
$ 2.24万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640451/
关键词：
two channel Kondo model non-Fermi liquid Uranium compound magnetic impurity Anderson model numerical renormalization group ラウン化合物

项目摘要

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.

我们学习了以下科目。(1)已知杂质安德森模型（TAM）作为金属中磁性离子的基本模型，在大杂化极限下确实具有局部费米液体（LFL）性质。非费米液体（NFL）状态是否出现在LAM中？如果是这样的话，在LFL和NFL州之间会发生什么样的转变？(2) system1 U_xTh_<1-x>Ru2Si_2表现出与双通道Kondo模式（TCKM）型NFL状态相似的异常低温行为。但其电阻率随温度的降低而降低。通常预计在TCKM中会增加。这种电阻率是否可以根据IAM来解释？(3)已知TCKM在T=0时的残差熵为1/ In。这将在晶体对称性降低的情况下释放出来，比热在某一特征温度下出现峰值。磁化率随- In T的增加在特征温度附近的表现如何？得出以下结论。(1)当杂化改变时，根据晶体场的不同，IAM具有不同类型的基态，包括LFL和NFL性质。(2)当f^2和f^3之间的价态波动占主导地位时，电阻率下降。(3)特征温度约为晶体场分裂的1/10。在这个温度下，磁化率的增加达到饱和。当参数非常接近LFL状态的过渡点时，NFL状态下的残差熵仍然是1/ in 2。最近测量了U_xTh_<1-x>Ru_2Si_2在强磁场下的比热，没有观察到残余熵。基于本研究的结果，我们可以得出结论，TCKM类型的情景似乎并不仅仅适用于该系统。动态扬-泰勒效应的作用现在正在考虑之中。