  The periodic Anderson lattice model for the crystalline electric field
(CEF)split 4f quartet states is used to describe the Yb-based Kondo
insulators/semiconductors. In the slave-boson mean-field approximation, we
derive the hybridized quasiparticle bands, and find that decreasing the
hybridization difference of the two CEF quartets may induce an
insulator-to-metal phase transition. The resulting metallic phase has a hole
and an electron Fermi pockets. Such a phase transition may be realized
experimentally by applying pressure, reducing the difference in hybridization
of the two CEF quartets.
