  An evaporative cooling was performed to cool the fermionic 173Yb atoms in a
crossed optical dipole trap. The elastic collision rate, which is important for
the evaporation, turns out to be large enough from our study. This large
collision rate leads to efficient evaporation and we have successfully cooled
the atoms below 0.6 of the Fermi temperature, that is to say, to a quantum
degenerate regime. In this regime, a plunge of evaporation efficiency is
observed as the result of the Fermi degeneracy.
