Manipulation of crystalline structure, magnetic performance, and topological feature in Mn3Ge films.

The Mn₃X (where X = Ga, Ge, Sn, etc.) compounds have appealing prospects for spintronic applications due to their various crystal structures and magnetic properties for the design of reliable high-density memories. However, controlled growth of high-quality Mn₃X thin films remains challenging in material science. Here, we reported the controlled film growth of Heusler alloy Mn₃Ge, which could crystallize in respective tetragonal and hexagonal structures. The tetragonal D0₂₂-type Mn₃Ge film exhibits strong perpendicular ferromagnetic anisotropy, while the hexagonal D0₁₉-type Mn₃Ge film indicates non-collinear triangular antiferromagnetic order. From our experimental observations of structure characterizations, magnetic properties, anomalous Hall effect, and magnetoresistance measurements, we realized the manipulation of spin orientations and topological features. Majority/minority spin polarized Fermi surface and density of states of both tetragonal and hexagonal Mn₃Ge structures were investigated by density functional theory calculations. Our work not only opens up technology routes toward the development of Mn₃X-based devices for applications in topological spintronics and spin-torque memories but also leads to engineer the physical properties for fundamental study. [ABSTRACT FROM AUTHOR]