Two-Channel Kondo Effect Emerging from Np and Pu Ions

On the basis of an idea of the electron-hole relation between $f^2$ and $f^4$ states in a $j$-$j$ coupling scheme, we point out a possibility that two-channel Kondo phenomena can be observed even in cubic transuranium compounds including Np and Pu ions with local $\Gamma_3$ non-Kramers doublet ground state. For the purpose, we analyze a seven-orbital impurity Anderson model hybridized with degenerate $\Gamma_8$ conduction electron bands by employing a numerical renormalization group method. From the numerical results for the case of four local $f$ electrons, corresponding to Np$^{3+}$ and Pu$^{4+}$ ions, we confirm that a residual entropy of $0.5\log 2$, a characteristic of two-channel Kondo phenomena, appears for the case with the local $\Gamma_3$ doublet ground state.