Crossover from a Low-Temperature Heavy-Quasiparticle State to a High-Temperature Local-Moment State in the Heavy-Fermion System

摘要

We investigate the crossover from a low-temperature state in which heavy quasiparticles are formed to the high-temperature state in which conduction electrons separated from the degrees of freedom of f electrons exist in the heavy-fermionic model with the hybridization between conduction electrons and f electrons. To study the temperature dependence of spectral functions, the dynamical mean-field approach is adopted to treat the electron correlation between f electrons. By considering the competition between the effective hybridization energy V* and the characteristic energy Gamma of quasiparticle excitation, it is found that there is a condition, that is, Gamma > V*, for a system to show this crossover, whereas for Gamma less than or similar to V*, the quasiparticle states in the hybridization band become ambiguous with increasing temperature before the effective hybridization between f electrons and conduction electrons is lost.