fullHeusler

Full Heusler alloys are a family of intermetallic compounds with the chemical formula X2YZ, where X and Y are transition metals and Z is a main-group element. They crystallize in the L21 cubic structure, consisting of four interpenetrating face-centered cubic sublattices. In the ordered L21 arrangement, X atoms occupy two sublattices while Y and Z occupy the remaining ones, a configuration that distinguishes full Heuslers from half-Heuslers, which have a different stoichiometry and partial site occupancy.

Magnetic and electronic properties are a key feature of many full Heuslers. They commonly exhibit ferromagnetic or ferrimagnetic ordering and can have high Curie temperatures. A notable aspect is the potential for high spin polarization at the Fermi level, with some compounds predicted or observed to be half-metallic. This combination makes them attractive for spintronic applications such as spin valves, magnetic tunnel junctions, and spin injectors.

Common examples include Co2MnSi, Co2MnGe, Co2FeAl, and Ni2MnGa, with variations in the X, Y, and Z elements enabling a wide range of properties. Inverse Heuslers, where the X atoms occupy different lattice sites, also exist and exhibit distinct magnetic structures.

Synthesis and ordering are important for performance. Thin films are typically grown by sputtering or molecular beam epitaxy, followed by annealing to achieve the L21 ordered phase. Chemical disorder, including anti-site mixing (DO3/B2-type), can reduce magnetic moments and spin polarization, compromising device performance.

Applications of full Heuslers in spintronics continue to motivate research, including efforts to tailor composition, disorder, and interfaces to realize robust, room-temperature spin-polarized transport.