Tuning the structural, magnetic, and transport properties of Mn3Ga alloys

Mn 3 Ga alloys with different crystal modifications, including a disordered L1 2 -type cubic structure, a D0 22 -tetragonal structure, and a D0 19 -hexagonal structure showing two isomorphic heteromagnetic phases, ε-phase and η-phase, were investigated systematically. We found that the disordered cubic phase and the hexagonal ε-phase can be synthesized with Mn compositions ranging from 70 to 75 at. % by rapid melt-spinning. Moreover, the disordered cubic phase could transform to the tetragonal phase after being subjected to low-temperature postannealing. Most importantly, we found that proper postannealing conditions can enable these different crystal modification phases to transform to the hexagonal η-phase. As a result, the two isomorphic heteromagnetic hexagonal phases are clearly distinguished, and their interesting magnetic and transport properties are discussed.