Resistivity model for both paramagnetic and ferromagnetic phases
  The resistivity, $\rho$ as a function of temperature and ionization energy (doping) and magnetization respectively is derived with further confinements from spin-disorder scattering. The computed $T_{crossover}$ below $T_C$ and carrier density in Ga$_{1-x}$Mn$_x$As system are 8-12 K and 10$^{19}$ cm$^{-3}$, remarkably identical with the experimental values of 10-12 K and 10$^{18}-10^{20}$ cm$^{-3}$ respectively. 
Andrew Das Arulsamy