Stability of Non-Fermi Liquid in Kondo Effect due to (5f)^2 Configuration

概要

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The stability of the non-Fermi liquid (NFL) in Kondo effect is studied by considering the excitedstates of the 5 /-electrons. First, in order to examine their effects in the strong correlation limit,the exchange model is derived for a tetragonal crystal field by restricting the localized states inf' to a non-Kramers doublet and a singlet; all the states are taken into account for f". Thenumerical renormalization group analysis for this model shows that the singlet state in f' andone of the excited states in f" play an important role to stabilize the Ferumi liquid (FL) over theNFL. Second, the same problem is examined for the six-fold orbitally degenerate Anderson modelby considering all the local excited states, The competition between FL and NFL sensitivelydepends on the Coulomb and Hund couplings, the orbital anisotropy and the hybridization term.The six-fold orbital degeneracy is also important to realize NFL; in fact a similar analysis on thefour-fold orbitally degenerate Anderson model does not lead to NFL.
社団法人日本物理学会の論文
1997-05-15