Magnetic Fen+1ACn (n=1, 2, 3, and A = Al, Si, Ge) phases:: from ab initio theory

We have investigated the structural stability and magnetism for a set of compounds Fe(n+1)AC(n) (n = 1, 2, 3, and A = Al, Si, Ge) using ab initio theory. From our calculation, we have shown that some Fe(n+1)AC(n) phases (n = 2) with the general MAX phase formula and a layered hexagonal structure that belongs to space group D-6h(4)-P6(3)/mmc can have a combination of properties of the MAX phase at the same time as having magnetism. The Fe3AlC2 phase shows the most stable ferromagnetic properties among these MAX phases and the magnetic moment is 0.73 mu(B)/Fe atom. In addition, the phase stability is predicted by comparing the total energy of the Fe2AlC and Fe2SiC phases with the total energy of the competing equilibrium phases at the corresponding composition.