FERRIMAGNETIC TAU-MNAL CO SUPERLATTICES ON GAAS/

We report on the ferrimagnetic superlattice ordering in epitaxial tau- MnAl/Co superlattices on GaAs. For ultrathin Co layers (3.5-7 Angstrom ), both the ferromagnetic tau MnAl and Co layers display a large perpe ndicular magnetic anisotropy together with an antiferromagnetic interf ace exchange coupling. As a result, an abrupt transition from the ferr omagnetically aligned state at saturation to a ferrimagnetic superlatt ice ordering occurs at unusually high fields (3-7 T) followed by a rev ersal of the total sample moment at low fields (0.3-1.6 T).