  The $\nu=2/5$ state is spin-unpolarized at weak magnetic field and fully
polarized at strong field. At intermediate field, a plateau of half the maximal
polarization is observed. We study this phenomenon in the frame of composite
fermion theory. Due to the mixing of the composite fermion Landau levels, the
unidirectional charge/spin density wave state of composite fermions is lower in
energy than the Wigner crystal. It means that transport anisotropy, similar to
those for electrons in higher Landau levels at half fillings, may take place at
this fractional quantum Hall state when the external magnetic field is in an
appropriate range. When the magnetic field is tilted an angle, the easy
transport direction is perpendicular to the direction of the in-plane field.
Varying the partial filling factor of composite fermion Landau level from 0 to
1, we find that the energy minimum occurs in the vicinity of one-half.
