The Relationship between Magnetism and Composition in Heusler Co2CrAl-based Thin Films
- Program: Materials Science and Engineering
- Course: Senior Design II EN.510.434
Project Description:
A number of L21 phase alloys (composition X2YZ) have exceptional magnetoelectric properties. Within this group, Co2CrAl is predicated as a promising candidate for half-metallic ferromagnetism. However, synthesis of this stoichiometry is a challenge because of its susceptibility to secondary phase precipitation and structural defect formation, causing discrepancies in the theoretical and experimentally observed properties.
In addition, recent techniques for growing incongruent melting compounds have produced alloys that suffer from phase transformation via spinodal decomposition, prompting secondary phase formation that also depresses magnetic properties. Since this secondary phase is difficult to dissolve once it is formed, it is necessary to access a single-phase field from the start.
This project explores using the space of off-stoichiometry and elemental substitution to design an optimized composition that avoids the region of immiscibility and therefore realizes desirable magnetic behavior.
