Mn 3− x Ga (0 ≤ x ≤ 1): Multifunctional thin film materials for spintronics and magnetic recording

Tetragonal Mn 3− x Ga (0 ≤  x  ≤ 1) epitaxial films possess exceptional magnetic and electronic properties. Stoichiometric Mn 3 Ga 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. Mn 2 Ga, 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 (∼15 kb µm −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 ‐Mn 3 Ga films are antiferromagnetic, which could be useful for exchange bias.(a) The tetragonal D0 22 unit cell of Mn 3 Ga. Ga atoms are ordered in a body‐centred tetragonal structure and Mn atoms occupy 2b (red) and 4d (green) sites. (b) The hexagonal D0 19 unit cell of Mn 3 Ga.