Magnetic coupling in the cluster Fe2Mn4 : A fully unconstrained density-functional study

Ab initio calculations using the fully unconstrained magnetization option of the density-functional computation package SIESTA predict that groundstate Fe2Mn4 has a distorted octahedral structure and, unlike Mn6, collinear magnetic order of the kind recently predicted for ultrathin Mn films on the (001) surface of Fe. The two Fe atoms are adjacent and couple ferromagnetically both to each other and to their nearest two Mn neighbours, to which the other two Mn atoms couple antiferromagnetically.