First-principles calculations of Fe on GaAs(100)

We have calculated from first principles the electronic structure of 0.5-ML upto 5-ML-thick Fe layers on top of a GaAs(100) surface. We find the Fe magnetic moment to be determined by the Fe-As distance. As segregates to the top of the Fe film, whereas Ga most likely is found within the Fe film. Moreover, we find an asymmetric in-plane contraction of our unit cell along with an expansion perpendicular to the surface. We predict the number of Fe $3d$ holes to increase with increasing Fe thickness on p-doped GaAs.