Electronic band structure calculations on thin films of the L21 full Heusler alloys X2YSi (X, Y = Mn, Fe, and Co): Toward spintronic materials

Abstract To design half-metallic materials in thin film form for spintronic devices, the electronic structures of full Heusler alloys (Mn 2 FeSi, Fe 2 MnSi, Fe 2 FeSi, Fe 2 CoSi, and Co 2 FeSi) with an L2 1 structure have been investigated using density functional theory calculations with Gaussian-type functions in a periodic boundary condition. Considering the metal composition, layer thickness, and orbital symmetries, a 5-layered Co 2 FeSi thin film, whose surface consists of a Si layer, was found to have stable half-metallic nature with a band gap of ca. 0.6 eV in the minority spin state. Using the group theory, the difference between electronic structures in bulk and thin film conditions was discussed.