Atomic Ordering and Electronic Structure of X₂YSn Heusler Alloys: A First-Principles Study

The Heusler material class, comprised primarily of ternary intermetallic alloys, boasts a wide range of properties including half-metallic ferromagnetism, topological band structure, and band gap tunability. The competition between the “Full-Heusler” L2₁ and “Inverse-Heusler” XA space groups, complicated by antisite disorder, can disrupt material systems. Understanding the role of element-choice in phase stability and electronic structure is therefore critical to identifying materials robust against possible phase disorder.



Density-functional theory calculations have been performed for the X₂YSn material class (X =Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) for the both the L2₁ and XA phases, investigating the stability against antisite disorder. An XA-L2₁ phase transition is found with increasing x-site valency, accompanied by an increasing antialignment of the x-site and yttrium moments, corresponding to a spin-dependent shift in DOS peaks, indicating an asymmetric filling of electron orbitals within the systems in question. This results in movement of half-metallic gaps across the fermi-energy, indicating possible spin-polarization tuning applications.