Non-Fermi Liquid Behavior of U-impurity with $\mbi{f}^{2}$-Singlet Ground State

概要

論文の詳細を見る
It is shown by the Wilson numerical renormalization-group approach that a U-impurity with an $f^{2}$-singlet ground state exhibits an unstable non-Fermi liquid (NFL) fixed point due to the balance between Kondo singlet and crystalline-electric-field singlet ground state. The puzzling behavior of R1-xUxRu2Si2 (R$=$Th, Y and La, $x\le 0.07$) can be explained if we assume that the singlet ground state is realized and the Kondo temperatures in each orbital are of different orders of magnitude. For a wide region in parameter space, the system shows the NFL behavior as a transient phenomenon in a experimentally possible temperature range. Results for the temperature dependence of resistivity, magnetic susceptibility and the Sommerfeld coefficient with and without a magnetic field reproduce the behavior observed in Th1-xUxRu2Si2. Less anomalous properties of R1-xUxRu2Si2 (R$=$Y and La) can be understood in the same scenario provided that these compounds have different sets of parameters.
2002-02-15