Highly Reduced Saturation Magnetization in EpitaxiallyGrown Ferrimagnetic Heusler Thin Films

The key of spintronicdevices using the spin-transfer torquephenomenon is the effective reduction of switching current density by lowering the damping constant and the saturation magnetizationwhile retaining strong perpendicular magnetic anisotropy. To reduce the saturation magnetization, particular conditions such as specific substitutions or buffer layers are required. Herein, we demonstrate highly reduced saturation magnetizationin tetragonal D022 Mn3–xGa thin films prepared by rf magnetron sputtering, where the epitaxial growth is examined on various substrates without any buffer layer. As the lattice mismatch between the sample and the substrate decreases from LaAlO3 and (LaAlO3)0.3(Sr2AlTaO6)0.7 to SrTiO3, the quality of Mn3–xGa films is improved together with the magnetic and electronic properties. Especially, the Mn3–xGa thin film epitaxially grown on the SrTiO3 substrate, fully oriented along the c axis perpendicular to the film plane, exhibits significantly reduced saturation magnetizationas...