Tailoring magnetization and anisotropy of tetragonal Mn3Ga thin films by strain-induced growth and spin orbit coupling

Tetragonal Mn3Ga thin films were epitaxially grown with and without strain on Cr and Mo crystalline buffer layers, respectively, using rf-magnetron sputtering. Epilayers grown on Cr with a lattice mismatch of 4.16%, exhibit a high magnetization of 220 kAm−1 and high perpendicular magnetic anisotropy. These characteristics are attributed to interfacial strain. Additionally, a soft ferromagnetic component is observed in these films but not in relaxed layers grown on Mo, where Δa/a is −0.1%. These latest films exhibit a low magnetization of 80 kAm−1 and both perpendicular and in-plane magnetic anisotropies. We propose that high spin orbit coupling of Mo-5s14d5 orbitals from the buffer layer and strong hybridization with Mn3+-3d4 orbitals from the magnetic layer are at the origin of in-plane anisotropy at the interface, while Mn3Ga magnetocrystalline anisotropy leads to perpendicular anisotropy on the rest of the film.