Electronic Properties and Phase Stability of Full and Inverse Heusler X₂FeAl (X=20 transition metal elements) by First-Principle Calculations

Before intermetallic Heusler alloys can be best applied in spintronic devices, materials must be found that either (1) have strong energetic preference for atomic configurations with high spin polarization, or (2) exhibit spin polarizations that remain high even in the face of atomic disorder. Thus, these properties are targeted in our search for functional spintronic Heusler compounds, including both ab initio calculations and experimental verification.

Spin polarized density-functional theory (DFT) lattice parameter optimization, and density-of-states (DOS) and band structure calculations have been performed for full (L21) and inverse (XA) Heusler compounds with the formula X2FeAl (X = 20 different 3d, 4d, and 5d transition metal elements). Hf2FeAl is targeted for its (1) large formation energy difference between full and inverse Heusler phases, and (2) high spin polarization exhibited by the favored phase (full Heusler). Substitution of Al for other intermetallic elements at the Z site is also studied—with the hypothesis that the electronic properties will be minimally affected—since the Hf2FeAl Fermi surface is primarily comprised of Hf-d and Fe-d bands.