Elementary excitation for the orbitally degenerate Anderson model at finite temperatures

Abstract

The elementary excitation for the orbitally degenerate Anderson model at finite temperatures is studied using the Bethe ansatz solution. The formulation of the elementary excitation at finite temperatures is based on the method which was first developed by Yang and Yang for the one-dimensional boson system with the $\ensuremath{\delta}$-function type interaction. The expressions of the elementary excitation energy for the spin and the charge degrees of freedom are derived. Using the obtained expressions, the spin and the charge excitation spectrums are calculated numerically. With decreasing temperature, the peak structure grows in the spin excitation spectrum, whereas the weight around the impurity level increases in the charge excitation spectrum, below the temperature corresponding to the characteristic energy scale of the system. The crystalline-field effects on the elementary excitation spectrums are investigated in the Kondo regime, and the results are discussed in connection with the difference in the Kondo temperature. The relation between the obtained results and the thermodynamic quantity of the orbitally degenerate Anderson model is also discussed.