First-principles study of Fe 2 VAl and Fe 2 VAl/Si thin films and their magnetic properties

Abstract We studied thin films of Fe 2 VAl, Fe 2 VAl/Si, and a related compound using the total energy pseudopotential method. The internal atoms in a supercell of the repeated slab model were fully relaxed, except for Fe 2 VAl/Si. The detailed electronic and magnetic properties of structurally relaxed thin films of Fe 2 VAl, Fe 2 VAl/Si, and a related compound were calculated. These films are free-standing in the supercell, except for Fe 2 VAl/Si, which comprises Fe 2 VAl and Si (substrate) layers in a supercell. A thin film comprising Fe 2 V, Al, and Si (substrate) layers in the supercell (denoted as Fe 2 V/Al/Si) was also studied. Although electronic states of bulk Fe 2 VAl (full-Heusler) are metallic with pseudo-gap states around the Fermi level and nonmagnetic, the calculation results for Fe 2 VAl, Fe 2 VAl/Si, and Fe 2 V/Al/Si thin films in this study indicate that the films have ferromagnetic properties and their ferromagnetic states are energetically more favorable than nonmagnetic states. The magnetic moments are large and enhanced in the thin films. The magnetic moments of Fe in Fe 2 VAl (Fe 12 V 4 Al 4 ), Fe 2 VAl (Fe 20 V 8 Al 8 ), Fe 2 VAl/Si, and Fe 2 V/Al/Si thin films are 2.07 μ B /per atom, 1.29 μ B /per atom, 1.83 μ B /per atom, and 2.22 μ B /per atom, respectively. Although thin films have net ferromagnetic properties, the magnetic moments of the up and down spin states of Fe and V are antiferromagnetically aligned.