The site preference of 3d atoms Y in Mn 2 YAl (Y = V, Fe, Co) alloys and its influence on their electronic structures and magnetism have been studied by first-principles calculations. The results prove that elements with more valence electrons than Mn tend to enter the A (0, 0, 0) and C (, , ) sites and elements with fewer electrons prefer the B (, , ) site (Wyckoff positions). Meanwhile, it is found that for Mn 2 VAl and Mn 2 FeAl, a high spin polarization can be obtained whether the Y atom enters the (A, C) or the B site. In particular, Mn 2 VAl is half-metallic whether it forms the Cu 2 MnAl type or the Hg 2 CuTi type of structure. And a 100% spin polarization can be retained even when a 25% Mn-V antisite disorder occurs. This is quite preferable in practical applications. It is also found that the higher-valent element such as Co at the B (, , ) site has opposite effects and tends to close the energy gap. Finally, a systemic summarization on the electronic and magnetic properties of Mn 2 YAl (Y = Ti, V, Cr, Mn, Fe and Co) alloys was made. All of them except for Mn 2 TiAl are predicted as half-metals. The calculated total spin moment is an integral value and increases from -3ν B /f.u. for Mn 2 TiAl to +2ν B /f.u. for Mn 2 CoAl with increasing number of valence electrons. This agrees with the Slater-Pauling curve quite well. All the Mn 2 YAl alloys studied here are ferrimagnets.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Acoustics and Ultrasonics
- Surfaces, Coatings and Films