Compositionally modulated perpendicular magnetic anisotropy in tetragonal MnxAl films

Rare-earth-free perpendicularly magnetized L10-MnxAl alloy holds promise for low-cost permanent magnets and high-performance spintronic devices. In this Letter, we report a large-scale modulation of perpendicular magnetic anisotropy (PMA) in MnxAl films by changing the composition x. Through utilizing a lattice-matching B2-CoGa underlayer and optimizing growth conditions, the 30-nm-thick MnxAl films can maintain excellent PMA in a wide composition range (0.7 ≤ x ≤ 3). Meanwhile, the crystalline structure and magnetic properties exhibit a strong dependence on the composition with saturation magnetization changing from 443.75 to 20.52 kA/m, coercivity from 0.22 to 5.38 T, and PMA constant up to 1.34 × 106 J/m3. Combining experimental and calculation results, we confirm the existence of ferrimagnetic-like state in MnxAl under Mn-rich conditions. Further experiments validate the continued efficacy of our method in ultrathin MnxAl films, and spin–orbit torque induced magnetization switching has been realized. These results offer valuable insights into the modulation of fundamental properties and promote the potential application of MnxAl alloy.