Mn_xGa_1−x nanodots with high coercivity and perpendicular magnetic anisotropy

A Mn_xGa_1−x (x = 0.70) epitaxial thin film with perpendicular magnetic anisotropy and a large coercivity (μ₀H_c = 1 T) was patterned into nanodots using a combined self-assembly nanolithography and plasma etching procedure. Nanostructuring is achieved by self-assembly of polystyrene nanospheres acting as a mask on the magnetic film. This procedure allows easy patterning of a large area although introduced some chemical disorder, which resulted in a soft magnetic component in the magnetic hysteresis loops. However, chemical order was recovered after vacuum annealing at low temperature. The resulting nanodots retain the properties of the original film, i.e. magnetization oriented perpendicular to the particle and large coercivity. Our results suggest this lithography procedure could be a promising direction for nanostructuring tetragonal Heusler alloys.