  The undoped three-orbital spin fermion model for the Fe-based superconductors
is studied via Monte Carlo techniques in two-dimensional clusters. At low
temperatures, the magnetic and one-particle spectral properties are in good
agreement with neutron and photoemission experiments. Our most important
results are the resistance vs. temperature curves that display all the features
experimentally observed in BaFe$_2$As$_2$ detwinned single crystals (under
uniaxial stress), including a low-temperature anisotropy between the two
directions followed by a peak at the magnetic ordering temperature, here
induced by short-range spin order and concomitant Fermi Surface orbital order.
