Properties of the new high Tc materials: an analysis based on fermiology

A small value of the Fermi energy, E_f, in the new high T_c oxides and its consequences are the subject of this study. It is shown that the small value of E _f allows separation of the electronic contribution to the heat capacity in the high-temperature region E_fk _B>T>θ_D to determine the value of the electron-phonon coupling constant λ. The linear temperature dependence of the normal resistance is mainly due to a large anisotropy of the system. A small value of E_f allows the lattice contribution to the thermal conductivity to play a dominant role. A strong electron-phonon coupling is manifested in the increase of the thermal conductivity in the region T<T_c , and the appearance of such coupling is also connected with a small value of E_f