The theory of the heavy-fermion state in the Anderson lattice at absolute zero presented in the previous paper is extended to finite temperatures. This extension is systematically accomplished by using thermofield dynamics. The use of this formalism enables us to calculate the densities of states of the f electron and the conduction electron in the Anderson lattice at finite temperatures. An extremely sharp peak in each of the densities of states appears very near the Fermi level at low temperatures, along with a broad resonance peak outside the sharp peak. This narrow sharp peak corresponds to a heavy-quasifermion state. When the temperature increases, the sharp peak broadens and its height decreases due to a shortening of the quasifermion lifetime. This change may cause the crossover from the heavy-fermion state to the Kondo-impurity-like state observed in cerium and uranium compounds.
ASJC Scopus subject areas
- Condensed Matter Physics