Tetragonal Mn3-xGa (0 <= x <= 1) epitaxial films possess exceptional magnetic and electronic properties. Stoichiometric Mn3Ga crystallizes in the D0(22) structure (abstract figure) and is a collinear ferrimagnet with an easy c-axis. It exhibits a unique combination of low magnetization, high uniaxial anisotropy, high Curie temperature and high spin polarization, which suit the requirements for spin torque memories down to 10 nm in size. Mn2Ga, on the other hand, exhibits much higher magnetization, high perpendicular anisotropy and high Curie temperature but a lower spin polarization, which make it a potential candidate for high density bit-patterned recording with areal densities up to 10 Tb inch(-2) (similar to 15 kb mu m(-2)) and 10-year thermal stability. The flexibility of the D0(22) structure allows a variety of magnetic materials to be synthesized with varying x to suit specific magnetic applications. Hexagonal D0(19)-Mn3Ga films are antiferromagnetic, which could be useful for exchange bias.