Tuning the magnetic properties of Mn-deficient Mn3​Ga through Al and Sn doping

Magnetic materials exhibiting complex magnetic ordering are of significant interest due to their unique and tunable magnetic, electronic, and structural properties. We have investigated one such compound, Mn3Ga, which can be synthesized in cubic, tetragonal and hexagonal structures exhibiting antiferromagnetic, ferrimagnetic and paramagnetic properties, respectively, by tuning its elemental composition and synthesis parameters. Our study reveals that the slightly Mn deficient compound Mn2.9Ga can be synthesized in the ferrimagnetic tetragonal structure with a Curie temperature (TC) of 818K, a high field magnetization (M3T) of 6.4 emu/g, and a coercivity (Hc) of 1.62 kOe. Notably, its magnetic properties can be significantly improved by doping the Ga site with small amounts of Al or Sn. The Sn-doped and Al-doped samples Mn2.9Ga0.9Sn0.1 and Mn2.9Ga0.9Al0.1 remain tetragonal and exhibit Tc values of 834 K and 866 K; M3T of 16.5 emu/g and 23.4 emu/g; and Hc of 3.3 kOe and 3.7 kOe. All samples were prepared using arc-melting and annealing techniques. The results of this investigation are particularly interesting, as the competing ferromagnetic and antiferromagnetic ordering can give rise to nontrivial topological states with potential applications in spintronics.