ON THE THERMODYNAMICAL PROPERTIES IN THE SLAVE-BOSON MEAN-FIELD THEORY OF HUBBARD-MODEL

The effect of spin polarization in the slave boson mean field theory in the strongly correlated heavy electron systems is discussed concerning the thermodynamical properties of the Hubbard model. The free energy is evaluated by taking into account the effective reduction of the quantum states due to the exclusion of double occupation im a site through the introduction of the spin-dependent slave boson. The magnetic susceptibility, calculated as a function of temperature, shows the Fermi liquid property at low temperature and the local moment behaviour with the proper Curie constant at high temperature. The present results, including the temperature dependence of the specific heat, are compared with the previous results without the reduction of quantum states.