Multiple collinear magnetic arrangements in thin Mn films supported on Fe(001). Antiferromagnetic versus ferromagnetic behavior

We present a theoretical study of the magnetic properties of thin Mn films of 6 and 7 monolayers supported on Fe(001). The ab-initio tight binding linear muffin tin orbital (TB-LMTO) method was used to investigate the competition between ferromagnetic (F) and antiferromagnetic (AF) couplings within the system. We found several collinear magnetic solutions that may coexist at room temperature. The most stable configurations are characterized by AF coupling between the surface and subsurface Mn layers together with F coupling between Mn and Fe at the interface. The ground state arrangements for the 6 and 7 Mn films display opposite sign of the surface magnetic moment relative to the Fe substrate. The implications of these results in the possible onset of non-collinear magnetism when a step is present at the interface are discussed in comparison with Cr/Fe systems where non-collinear magnetism has been recently reported.