Mn₃Ga is an interesting compound for studying solid-state phase transformations and the manipulation of polycrystalline microstructure applying a high external magnetic field. On one side, the three different modifications of Mn₃Ga show diverging magnetic properties. While the cubic and hexagonal structure exhibit mainly antiferromagnetic behaviour, the tetragonal modification is ordered ferrimagnetically and, hence, thermodynamically favoured by magnetic field annealing. On the other side the hexagonal and tetragonal phase, both promising materials for spintronic application, are characterized by a high anisotropy in magnetic susceptibility. This anisotropy is crucial for texturing the microstructure via magnetic field processing, as an innovative approach for further improvement of the magnetic properties of Mn₃Ga is provided.

Starting from predominantly cubic material, we investigated the intermediate formation of hexagonal Mn₃Ga at different temperature regimes; i.e. as a competing phase transformation to recrystallisation of the cubic phase at 850°C and during formation of the tetragonal phase at 400°C. In both cases, application of an external magnetic field of several Tesla promoted the intermediate phase transformation, as has been confirmed by X-ray diffraction. The effect of the altered transformation process on the microstructure and consequent magnetic properties was analysed by means of optical/electron microscopy and SQUID magnetometry, respectively. Moreover, differential thermal analysis was performed to gain some deeper understanding of the intermediate phase transformation’s mechanism.