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Although a cubic phase of Mn3Ga with an antiferromagnetic order has been theoretically predicted, it has not been experimentally verified in a bulk or film form. Here, we report the structural, magnetic, and electrical properties of antiferromagnetic cubic Mn3Ga (C-Mn3Ga) thin films, in comparison with ferrimagnetic tetragonal Mn3Ga (T-Mn3Ga). The structural analyses reveal that C-Mn3Ga is heteroepitaxially grown on MgO substrate with the Cu3Au-type cubic structure, which transforms to T-Mn3Ga as the RF sputtering power increases. The magnetic and magnetotransport data show the antiferromagnetic transition at TN = 400 K for C-Mn3Ga and the ferrimagnetic transition at TC = 820 K for T-Mn3Ga. Furthermore, we find that the antiferromagnetic C-Mn3Ga exhibits a higher electrical resistivity than the ferrimagnetic T-Mn3Ga, which can be understood by spin-dependent scattering mechanism.

A proximity effect between magnetic materials and topological surface states can generate and modulate the localized spins without complicated material structures, but its origin is not clearly verified. MnSi single layer and MnSi/Bi2Se3 bilayer on Al2O3(001) substrates are fabricated by magnetron co‐sputtering and molecular beam epitaxy systems, in which a large proximity effect between the chiral magnetic structure and the topological surface states is manifested. The magnetic and electronic properties of both samples are meticulously compared and the proximity‐induced magnetism enhancement in the MnSi/Bi2Se3 bilayer is found. Interestingly, this effect persists up to temperatures above 300 K. Furthermore, for the MnSi/Bi2Se3 bilayer, the increase of charge carrier density and the decrease of carrier mobility near the Curie temperature TC = 40 K are observed, which can mediate the ferromagnetic exchange interaction enhancing the magnetization. The finding provides insight into a new platform to consist of materials with distinct topological phases for future spintronic devices.